Sylvie Cointe

Éric Rhéaume

Catherine Martel

Olivier Blanc-Brude

Evemie Dubé

Florence Sabatier

Francoise Dignat-George

Jean-Claude Tardif

Arnaud Bonnefoy

Françoise Dignat-George

Thrombospondin-1-Derived Peptide RFYVVMWK Improves the Adhesive Phenotype of CD34 + Cells from Atherosclerotic Patients with Type 2 Diabetes

Keywords: Thrombospondin-1 (TSP-1), Atherosclerosis, Type 2 diabetes (T2D), CD34, CD47

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

CD34 is a marker of hematopoietic stem cells (HSCs) that is also expressed on several non-HSCs including endothelial and epithelial progenitors, embryonic fibroblasts, multipotent mesenchymal stromal cells (MSCs), and interstitial dendritic cells. The plasticity of CD34 + cells and their paracrine-stimulating properties on the endothelium during hypoxia make these cells potential candidates for cell transplant therapies combating ischemic diseases such as cardiac failure 1 .

Circulating progenitor cells are known to contribute to neoangiogenesis during numerous processes including healing, lower limb ischemia, vascular graft endothelialization, atherosclerosis, post-myocardial infarction, lymphoid organ neovascularization, and tumoral growth 2 . Clinical trials have demonstrated that intracoronary administration of bone marrow-derived mononuclear cells (BM-MNCs) from autologous progenitor cells or peripheral blood (PB) CD34 + cells mobilized by granulocyte colony-stimulating factor improves the left ventricular ejection fraction and reduces the size of the infarcted area [START_REF] Caballero | Ischemic vascular damage can be repaired by healthy, but not diabetic, endothelial progenitor cells[END_REF][START_REF] Blanc-Brude | Abstract 895: CD47 activation by thrombospondin peptides enhances bone marrow mononuclear cell adhesion, recruitment during thrombosis, endothelial differentiation and stimulates pro-angiogenic cell therapy[END_REF] . However, the benefit of cell therapy is dampened by the negative impact of cardiovascular risk factors, such as atherosclerosis, obesity, and type 2 diabetes (T2D), on the number and function of progenitor cells, thereby jeopardizing their use for autologous treatment 5,6 . Interestingly, a reduced progenitor cell adhesion capacity has been reported in T2D 5,7 . Moreover, strategies aiming at preconditioning CD34 + cells or endothelial progenitor cells prior to injection in animal models of ischemia were reported to improve revascularization in vivo, together with increased adhesion capacity of cells in in vitro models 8 .

The ability of CD34 + cells to adhere and engraft onto damaged vessel walls is crucial to initiate neovascularization 9 . During this process, activated platelets are instrumental in targeting CD34 + cell recruitment to injured vessels via stromal cell-derived factor-1 (SDF-1a) secretion and chemotaxism 10 . Platelets also stimulate the "homing" of CD34 + cells, via CD62-CD162 interaction 11 and their differentiation into mature endothelial cells 8 . One of the most abundant proteins secreted by activated platelets is thrombospondin-1 (TSP-1), which is a multifunctional matricellular glycoprotein bearing proatherogenic, prothrombotic, as well as both pro-and antiangiogenic properties 12 . The interaction of TSP-1, through its COOH terminal RFYVVMWK sequence, with the transmembrane protein CD47 [integrin-associated protein (IAP)] occurs following a conformational reorganization of the C-terminal domain of TSP-1 13 .This interaction positively modulates the function of several integrins including CD51/CD61, CD41/CD61, and CD49b/CD29, thereby modulating cellular functions including platelet activation and adhesion, leukocyte adhesion, migration, and phagocytosis through heterotrimeric G i protein signaling [14][15][16][17] .

We have previously observed that TSP-1-deficient mice exhibit a significant drop in the vessel wall recruitment of BM-MNCs in a FeCl 3 -induced intravascular thrombosis mouse model 18 . We also found that ex vivo RFYVVMWK preconditioning of mouse BM-MNCs stimulates their recruitment to sites of intravascular thrombosis induced by FeCl 3

19

. Indeed, RFYVVMWK increased BM-MNCto-vessel wall interactions and decreased their rolling speeds to the damaged vessel wall, leading to a 12-fold increase in permanent cell engraftment 19 .

The goal of the present study was to analyze the proadhesive effects of RFYVVMWK preconditioning on CD34 + progenitor cells isolated from PB of atherosclerotic patients with T2D. We first explored their "proengraftment" phenotype through the measurement of a panel of biomarkers including cell adhesion receptors, platelet/CD34 + conjugates, and apoptotic markers. We next investigated whether this preconditioning could improve their capacity to adhere to stimulated endothelial cells and subendothelial components.

MATERIAL AND METHODS

Patients

Blood samples were drawn from participants after obtaining informed consent as part of a protocol approved by the ethics committee of the Montreal Heart Institute and in accordance with the recommendations of the Helsinki Declaration. A total of 40 adult males (>18 years old) with stable coronary artery disease or stable angina documented by angiography, all treated with antiplatelet agents and statins, were included in the study. Among these patients, 20 had T2D (T2D group) and 20 were nondiabetic (non-T2D group). The patients were predominantly hypertensive (n = 27), dyslipidemic (n = 38), overweight (n = 25), and with a smoking history (n = 27). Diabetic patients received biguanide (metformin) monotherapy (n = 10), biguanide + sulfonylureas (glyburide or glimepiride) bitherapy (n = 6), biguanide + sulfonylureas (glyburide) + DPP-4 inhibitor (gliptin) tritherapy (n = 2), or no medication (diabetes was controlled by diet). Exclusion criteria were acute coronary syndrome (ACS) or stroke within the past 6 months, treatment with insulin, treatment with peroxisome proliferator-activated receptors (PPARs; pioglitazone and rosiglitazone), extra cardiac inflammatory syndromes, surgery within the last 8 weeks, kidney or liver failure, use of systemic corticosteroids, cancer in the last 5 years, chronic anticoagulation, heart failure [NYHA class 3 or 4 and/or left ventricular ejection fraction (LVEF) <40%], and hemoglobin <100 g/L. Six healthy adult males [healthy donors (HD)] who showed no cardiovascular disease or known T2D were also recruited if they had not taken any medication during the past 15 days before blood sampling. All samples were analyzed in a single-blind manner with respect to the group (T2D or non-T2D).

Isolation of CD34 + and CD34 -Peripheral Blood Mononuclear Cells (PBMCs)

One hundred milliliters of blood was collected by venipuncture into syringes containing ethylenediaminetetraacetic acid (EDTA; 1.8 mg/ml of blood) (Sigma-Aldrich, St. Louis, MO, USA), dispensed into 50-ml conical tubes, and centrifuged at 400 ´ g for 15 min at 20°C, to remove a maximum quantity of platelets while minimizing PBMC loss. EDTA was used throughout the isolation process to avoid platelet binding to CD34 + cells. The platelet-rich plasma (PRP; upper phase) was removed, and the remaining blood components were diluted 1:1 in phosphate-buffered saline (PBS) containing 2 mM EDTA and 0.5% fetal bovine serum (FBS) (Sigma-Aldrich) (PBS/EDTA/FBS). Ficoll at a density of 1.077 g/ml (Amersham Biosciences, Little Chalfont, UK) was added to samples in a ratio of 1:3 and centrifuged at 400 ´ g for 40 min at 20°C (without brakes). The resulting mononuclear cell ring was collected at the Ficoll/plasma interface. Cells were then washed twice with PBS/EDTA/FBS and incubated for 10 min at 4°C with 100 µl of FcR blocking reagent (Miltenyi Biotec, Bergisch Gladbach, Germany) to remove FcR-specific binding antibodies. Cells were then incubated for 30 min at 4°C with 100 µl of magnetic beads bearing anti-CD34 monoclonal antibodies (Microbead; Miltenyi Biotec). After washing with PBS/EDTA/FBS, cells were filtered (30-µm nylon cell strainer; Miltenyi Biotec) to remove cell aggregates or other large contaminants and loaded on a MACS magnetic column (Miltenyi Biotec). Unbound CD34 -cells were collected, while CD34 + PBMCs were retained on the column. After three washes with PBS/ EDTA/FBS, CD34 + cells were recovered in 1 ml of PBS/ EDTA/FBS. To increase the purity of CD34 + cells, this step was repeated once on a new column with the retained fraction. Finally, cell viability was measured with trypan blue (Sigma-Aldrich).

Cell Preconditioning With TSP-1-Derived Peptides

CD34 + and CD34 -cells were diluted either at a concentration of 1,000 cells/µl for adhesion assays or at a concentration of 4,000 cells/µl for flow cytometry assays. Cells were then preincubated with either 30 µM of the CD47 interacting peptide RFYVVMWK (amino acid sequence: Arg-Phe-Tyr-Val-Val-Met-Trp-Lys) (4N1-1; Bachem, Bubendorf, Switzerland), 30 µM of the RFYVVM truncated peptide devoid of CD47-binding activity (Arg-Phe-Tyr-Val-Val-Met) (4N1-2; Bachem), or saline (vehicle) for 30 min at 37°C.

Phenotyping of Preconditioned Cells

The phenotype of preconditioned cells (with TSP-1 peptides or the vehicle, as previously described) was analyzed by flow cytometry using fluorescent-labeled antibodies directed against biomarkers grouped in four panels: panel 1 with CD47 (clone B6H12; R&D Systems, Minneapolis, MN, USA) and TSP-1 (clone A4.1; Santa Cruz Biotechnology, Santa Cruz, CA, USA); panel 2 with the adhesion molecules CD29 (clone TS2/16; eBioscience, San Diego, CA, USA), CD51/CD61 (clone 23C6, eBioscience), and CD162 (clone KPL-1; BD Biosciences, Franklin Lakes, NJ, USA); panel 3 with CD62P (clone P.seK02.22; BD Biosciences); and panel 4 with the apoptosis and cell death markers phosphatidylserine (annexin V labeling), 4¢,6¢-diamidino-2-phenylindole (DAPI), and propidium iodide (PI) (BD Biosciences). Each panel also included antibodies against CD34 (clone 581; BD Biosciences), CD42b (platelet marker; clone HIP1; BioLegend, San Diego, CA, USA), and DAPI to discriminate living cells.

Cell suspension ( 4´ 10 3 cells/µl) was incubated with each antibody panel (previously centrifuged at 2 ´ 10 3 ´ g for 2 min to remove aggregates of antibodies) for 30 min at room temperature in the dark. Immunophenotyping of CD34 + cells was performed on an LSR II flow cytometer (BD Biosciences) and analyzed with Kaluza software (Beckman Coulter, Miami, FL, USA).

Detection of Integrin Polarization and Platelet/CD34 + Conjugates

CD29 and CD51/CD61 distribution on cell surfaces and platelet (CD42b + )/CD34 + cell conjugates was visualized by confocal microscopy (Zeiss Observer Z1 equipped with a Yokogawa CSU-X1 confocal head QuantEM 512SC camera; Intelligent Imaging Innovations, Denver, CO, USA).

Cell Adhesion Onto Collagen-Vitronectin Matrices

Ninety-six-well plates (Sarstedt, Nümbrecht, Germany) were coated overnight at 4°C in PBS containing a mixture of 0.3 µg/ml vitronectin (Sigma-Aldrich) and 1 µg/ml type I collagen (Sigma-Aldrich). The wells were then saturated with 0.1% gelatin [American Type Culture Collection (ATCC), Manassas, VA, USA] for 1 h at room temperature and washed with PBS. Twenty thousand cells in 200 µl of endothelial basal medium-2 (EBM-2; Lonza, Walkersville, MD, USA) were pretreated with either the vehicle, RFYVVMWK, or RFYVVM for 5 min at 150 ´ g at room temperature to quickly spin down the cells onto the matrix. Plates were then incubated for 30 min at 37°C and gently washed with EBM-2. Finally, 100 µl of 2% paraformaldehyde (PFA) and 100 µl of DAPI were sequentially added. Nuclei were counted using an inverted epifluorescence microscope (Axiovert 200M, camera AxioCam MRm; Zeiss, Stockholm, Sweden) coupled with the image analysis software ImageJ [National Institutes of Health (NIH), Bethesda, MD, USA]. Results were expressed as the number of cells adhered per 20 ´ 10 3 cells originally loaded per well.

Cell Adhesion Onto HUVEC Monolayers

Human umbilical vein endothelial cells (HUVECs; PromoCell, Heidelberg, Germany) between passage 4 and 8 were seeded into 96-well plates for 48 h at a density of 25 ´ 10 3 cells/well. After 36 h at 37°C, 5% CO 2 concentration, and 95% relative humidity, HUVECs were stimulated for 18 h with 1 ng/ml tumor necrosis factor-a (TNF-a; R&D Systems) or 10 ng/ml interleukin-1b (IL-1b; Sigma-Aldrich). Cells were then washed twice with Hank's balanced salt solution (HBSS). To differentiate PBMCs from HUVECs during cell counting, PBMCs were prelabeled with 0.5 µg/ml calcein-AM (Sigma-Aldrich) in EBM-2 for 1 h at 37°C and then washed and resuspended in EBM-2 before seeding onto HUVEC monolayers. As for matrix adhesion assays, microplates were centrifuged for 5 min at 150 ´ g at room temperature to quickly spin down the cells onto the HUVECs and then incubated for 1 h at 37°C. After two washes with HBSS, the cells were fixed with 2% PFA. Calcein-AM-labeled PBMCs were then counted by fluorescence microscopy and ImageJ software. Results were expressed as the number of adherent cells per 10 ´ 10 3 cells originally loaded in each well. All experiments were performed in duplicate.

Statistics

Analyses were performed using the GraphPad Prism software v.5.01 (GraphPad Software, San Diego, CA, USA). Data were expressed as mean ± standard error of the mean (SEM). The Kruskal-Wallis nonparametric test was used to compare the three preconditioning treatments (vehicle, RFYVVMWK, and RFYVVM) in cell adhesion assays and the Mann-Whitney nonparametric test to compare biomarkers. Values of p < 0.05 were considered statistically significant.

RESULTS

Patient Characteristics

Both T2D and non-T2D had similar demographic characteristics (Table 1). Almost all participants (95%) had dyslipidemia and high cholesterol levels. The majority was also overweight (BMI > 27 kg/m 2 ) with a smoking history (n = 31). Beside a hypoglycemic therapy in T2D, there were no significant differences in drug regimen, with all patients being treated with antiplatelet drugs and statins. As expected, blood glucose (+40%; p < 0.001) and glycated hemoglobin (+19%; p < 0.001) were significantly higher in T2D participants. T2D also had higher triglyceride levels compared to non-T2D participants (+70%; p < 0.002).

Stimulation of Platelet/CD34 + Conjugate Formation by RFYVVMWK

Circulating CD34 + and CD34 -PBMCs were isolated from HD, T2D, and non-T2D blood by immunomagnetic separation and quantified. The purity of the isolated CD34 + cells was 92 ± 4%. No significant difference was found in total PBMCs (167.7 ± 50.2 ´ 10 6 PBMC/100 ml blood in T2D vs. 141.5 ± 32.5 ´ 10 6 in non-T2D and 136. 4 ± 38.8 ´ 10 6 in HD; p = 0.2) and CD34 -cells (77.2 ± 3.1 ´ 10 6 CD34 - cells/100 ml blood in T2D vs. 62.0 ± 2. 3 ´ 10 6 in non-T2D and 66.6 ± 2.5 ´ 10 6 in HD; p = 0.15). However, twice the amount of CD34 + PBMCs were retrieved from the blood of T2D participants compared to non-T2D and HD participants [218.9 ± 124.1 ´ 10 3 cells per 100 ml of blood vs. respectively, 101.6 ± 29.0 ´ 10 3 cells (p < 0.001) and 117.5 ± 49.8 ´ 10 3 (NS)]. The CD34 + /total PBMC ratio was also significantly higher in cell fractions isolated from T2D participants [0.13 ± 0.06% in T2D vs. 0.075 ± 0.03% in non-T2D (p = 0.0011), and 0.1 ± 0.07% (p = 0.06) in HD]. Although a double enrichment process and extensive wash were used during the purification of CD34 + cells, platelets were still detectable in the final cell preparations (average of 23.5 ´ 10 3 platelets/10 3 CD34 + cells). Using flow cytometry, we measured the extent of platelet/CD34 + cell conjugate formation (hereafter referred to as CD42b + /CD34 + conjugates) in samples and the effect of TSP-1 peptide preconditioning. RFYVVM preconditioning had no significant effect on conjugate formation, with 1.4% CD42b + /CD34 + conjugates in T2D and 2% in the non-T2D participants (NS). RFYVVMWK increased the percentage of CD42b + /CD34 + conjugates up to 11% in T2D (p < 0.0001 vs. RFYVVM) and 9% in non-T2D participants (p < 0.0001 vs. RFYVVM). Progenitor cellplatelet conjugate formation following RFYVVMWK treatment was confirmed by assessing the expression of CD42b and CD34 antigens by confocal microscopy (Fig. 1A).

Expression of CD47 and its Ligand TSP-1 CD47 expression was not modified by the RFYVVMWK preconditioning compared with the nonactive RFYVVM control peptide (Fig. 1B). We observed a 30% lower expression on T2D CD34 + cells compared to non-T2D cells (p < 0.01). CD47 expression was higher on CD42b + /CD34 + conjugates compared to CD42b -/CD34 + cells, probably due to the presence of CD47 on platelets (p < 0.05). TSP-1 was barely expressed on CD42b + /CD34 + conjugates and CD42b -/CD34 + preincubated with RFYVVM (Fig. 1C). RFYVVMWK induced a high expression of TSP-1 on both T2D and non-T2D CD34 + cells, in the presence or absence of platelets (all p < 0.001).

Expression of CD62P and CD162

RFYVVMWK induced a significant increase in CD62P on T2D and non-T2D CD42b + /CD34 + conjugates [+146% (p < 0.001) and +129% (p < 0.001) vs. RFYVVM, respectively], and a low increase in CD42b -/CD34 + cells [+26% (p < 0.01) vs. +25% (p < 0.001)] (Fig. 1D). By contrast, CD162 expression remained unchanged (Fig. 1E).

Expression of Adhesion Receptors CD29 and CD51/CD61

RFYVVMWK preconditioning of CD34 + cells significantly increased the expression of CD29 in both T2D and non-T2D participants [74% (p < 0.01) and 42% (p < 0.05) in CD42b + /CD34 + conjugates, respectively] (Fig. 2A). A strong increase in CD51/CD61 expression was also measured in T2D and non-T2D CD34 + cells [+2,715% (p < 0.001) and +3,260% (p < 0.001) in CD42b + /CD34 + conjugates, respectively] (Fig. 2B). Similar results were observed with CD42b -/CD34 + cells. Integrin polarization and clustering, which are indicators of integrin activation state, were also detected in RFYVVMWK stimulated cells by confocal microscopy (Fig. 2C).

Effect of RFYVVMWK on CD34 + Cell Viability

RFYVVMWK induced increased phosphatidylserine exposure (PI -/annexin V + cells) in both non-T2D CD34 + (7.2% vs. 0.15% with RFYVVM, p < 0.001) and T2D CD34 + cells (12.4% vs. 0.04% with RFYVVM, p < 0.001) (Fig. 3A). The percentage of PI + /annexin V + cells in response to RFYVVMWK was also significantly higher compared to RFYVVM but remained negligible (0.25% in non-T2D and 0.17% in T2D, p < 0.001 vs. RFYVVM) (Fig. 3B).

Cell Adhesion to Vitronectin-Collagen Matrix

CD34 + cells preincubated with vehicle (saline) adhered with values reaching 59.9 ± 8 cells/20 ´ 10 3 seeded cells, compared to 18.8 ± 2.9 CD34 -cells (p < 0.0001) (Fig. 4A). RFYVVMWK strongly increased the adhesion of CD34 + and CD34 -, respectively, by +368% and +468%. RFYVVM peptide had no significant effect, giving results comparable to vehicle. T2D CD34 + cells showed 67% less basal adherence (30 ± 4 cells) compared to non-T2D cells (90 ± 14 cells, p < 0.0001) (Fig. 4B). RFYVVMWK strongly increased the adhesion of T2D and non-T2D CD34 + cells by +786% (266 ± 54 cells) and +232% (296 ± 31 cells), respectively (p < 0.0001 compared to vehicletreated cells).

Cell Adhesion to HUVEC Monolayers Stimulated With TNF-α or IL-1β

We next measured the adhesion of CD34 + cells on HUVEC monolayers prestimulated with TNF-a or IL-1b. T2D and non-T2D CD34 + cells equally adhered to prestimulated HUVEC monolayers. Neither RFYVVMWK nor RFYVVM had a significant effect on cell adhesiveness (Fig. 4C andD).

DISCUSSION

Proangiogenic cell therapy offers many potential applications in regenerative medicine for the treatment of patients with ischemic diseases, particularly in cardiology. Promising preclinical studies have prompted the initiation of numerous clinical trials based on administration of progenitor cells. Several cellular functions are involved in the process of neoangiogenesis such as homing and recruitment of cells, proliferation, endothelial differentiation, and survival. However, cardiovascular risk factors such as T2D were associated with dysfunctional progenitor cells, including impaired adhesiveness 5,6 , which undermines their therapeutic value in autologous cell therapies 20 . CD34 + PBMC recruitment to damaged vessels is a crucial step to initiate the process of vascular repair and neovascularization 9 . In ex vivo settings, we observed a lower basal adhesion of T2D CD34 + cells to vitronectin-collagen matrix compared to the non-T2D CD34 + cells. We thus sought to investigate whether stimulating the adhesiveness of CD34 + PBMCs was feasible in an attempt to improve cell therapy efficiency in T2D.

The transmembrane protein CD47, TSP-1 receptor, associates with CD51/CD61, CD41a/CD61, CD49d/CD29, and CD49b/CD29 integrins to mediate cell adhesion and motility 17 . Herein we provide evidence that prestimulating CD34 + PBMCs with RFYVVMWK, a TSP-1-related peptide that activates CD47, restores and amplifies their adhesiveness to vitronectin-collagen matrix beyond the basal adhesion values obtained in non-T2D patients. In addition, we showed a strong increase in surface expression of CD29 and CD51/CD61 integrins following RFYVVMWK stimulation, thereby providing a possible mechanism to the increased adhesion of CD34 + cells to the subendothelial matrix components. Confocal microscopy strengthened this hypothesis by revealing polarization of integrin at the cell surface, consistent with the clustering process occurring during integrin activation.

The endothelial expression of CD51/CD61 (a v b 3 integrin) and its interaction with extracellular matrix components are crucial during angiogenesis 21 . This interaction triggers vascular endothelial growth factor (VEGF)-A-mediated full activation of VEGF receptor 2 (VEGFR-2), but also yields a strong antiapoptotic effect through the suppression of the p53 and the p53-inducible cell cycle inhibitor p21WAF1/CIP1 activities and the increase in the Bcl-2/Bax ratio 22,23 . Consistent with the later functions of CD51/CD61, RFYVVMWK priming did not compromise CD34 + cell survival, as assessed by annexin V/PI labeling. CD29 (b 1 ) integrin subsets diversely contribute to angiogenesis. Li and collaborators have associated CD29 expression levels with the rate of implantation and colonization of ischemic limbs with bone marrow-derived endothelial precursors, which is of critical importance for inducing therapeutic angiogenesis by cell implantation 24 .

Albeit standardized CD34 + PBMC isolation and purification techniques were used in this study, there were still platelet remnants in the positive fraction, as recurrently reported in the literature addressing CD34 + cell isolation and enrichment 25 . We observed a significant increase in platelet-CD34 + conjugate formation upon RFYVVMWK stimulation, along with an increased expression of CD62P restricted to platelet-CD34 + conjugates. These results are consistent with the previously reported activating effect of RFYVVMWK on platelets 26 . This activation, concomitant to CD34 + cell stimulation, induces platelet secretion and surface CD62P expression, thereby enabling platelets to interact with CD162 (PSGL-1) on CD34 + cells. As previously described by others, platelets are instrumental in neovascularization by targeting CD34 + cell recruitment to injured vessels and promoting their homing and maturation 8,10,11 .

Consistent with this rationale, RFYVVMWK stimulation had no significant effect on CD34 + PBMC adhesion on HUVEC monolayers, stimulated with either TNF-a or IL1-b. These results echo our observations in a TSP-1 knockout mouse model of FeCl 3 -induced intravascular thrombosis, in which we observed that TSP-1 was essential for bone marrow cell (BMC) recruitment to vascular injury sites 18 . We also reported that CD47 preactivation with RFYVVMWK strongly stimulated BMC adhesion and specific recruitment to sites of thrombosis in vivo 19 . The present findings suggest that stimulation by RFYVVMWK confers to CD34 + PBMCs an increased adhesiveness restricted to most damaged and de-endothelialized vascular areas exposing the matrix components, with limited stickiness to healthier areas.

It has previously been suggested that increased expression of adhesion molecules [including CD11a/CD18 (LFA-1), CD49d/CD29 (VLA-4), CD54 (ICAM-1), CD51/ CD61, and CD162] on CD34 + or endothelial progenitor cells and/or increased adhesiveness in vitro could translate into enhanced endothelial repair or neovascularization capacity in vivo [27][28][29] . In coherence with these observations, we have previously reported that priming BM-MNCs with RFYVVMWK results in increased proangiogenic activity in a mouse model of hindlimb ischemia and cell therapy 19 . However, additional studies are required to demonstrate whether the priming of CD34 + cells isolated from PB improves vascularization in vivo.

In a recent study, Albiero et al. suggested that increased adhesiveness of stem cells may hamper their ability of being mobilized from the bone marrow 30 . Our results are in line with the prospect of using the peptide ex vivo as a pretreatment strategy prior to administration of an autologous cell-based therapy product, rather than using RFYVVMWK in vivo. Thus, we anticipate that the endogenous mobilization of stem cells would not be affected. In addition, since the majority of current cell-based therapy strategies are using local injection in ischemic areas, it is unlikely that RFYVVMWK preconditioning of cells can favor homing of injected CD34 + cells into the bone marrow.

RFYVVMWK induced surface expression of TSP-1. This neo-expression was observed even in CD42b -/ CD34 + cells. The timeline of our experimental conditions suggest that TSP-1 originated from exocytosis or platelet secretion rather than from neosynthesis per se. The consequences of TSP-1 expression on CD34 + cells are difficult to anticipate as TSP-1 induces both positive and negative modulation of endothelial cell adhesion, motility, and growth through its interaction with a plethora of cell adhesion receptors, including CD47, CD36, CD51/CD61, and CD29 integrins, and syndecan 12 .

CD47 expression was not modulated upon RFYVV MWK stimulation. CD47 interaction with signal regulatory protein a (SIRP-a), expressed on macrophages and dendritic cells, negatively regulates phagocytosis of hematopoietic cells 31 . Interestingly, we observed that T2D CD42b + /CD34 + conjugates express significantly less CD47 on their surface compared to non-T2D cells. This lower expression of CD47 may contribute to a higher susceptibility of T2D CD34 + to phagocytosis in vivo. Yet, we could not demonstrate lower amounts of CD34 + in T2D PB as previously observed by others 32 . Surprisingly, using a singleblinded counting approach, we measured significantly higher levels of CD34 + cells recovered from T2D patients (n = 20) compared to non-T2D (n = 20). This could be due to the fact that counting of CD34 + cells was performed after enrichment of cells with an immunomagnetic CD34 antibody column rather than on the PB of patients, which may have introduced an unexpected bias in the quantification. In addition, several studies have suggested that glycemic control could impact circulating progenitor cell levels in diabetic patients. Indeed, oral antidiabetics were shown to attenuate the quantitative deficit and improve angiogenic function of progenitor cells in diabetics 33,34 . The underlying mechanisms probably involve reduction in inflammation, oxidative stress, and insulin resistance. Furthermore, a recent study reported a positive correlation between circulating CD34 + cell count and serum triglycerides in nonhypertensive elderly Japanese men, suggesting that triglycerides may stimulate an increase in circulating CD34 + by inducing vascular disturbance 35 . In our patient cohort, triglycerides were significantly higher in T2D patients despite statin treatment. In agreement with the study by Shimizu and collaborators 35 , CD34 + cell count significantly correlated with triglyceride levels in nonhypertensive patients (n = 11; Spearman test; r = 0.81; p < 0.004), but also to a lesser extent in the hypertensive group (n = 27; Spearman test; r = 0.43; p < 0.03).

In conclusion, priming CD34 + PBMCs from T2D patients with the TSP-1 carboxy-terminal peptide RFYVVMWK restores and amplifies their adhesion properties without compromising their viability. These findings may be instrumental to improve proangiogenic autologous cell therapy in several disease settings such as T2D.

Figure 1 .

 1 Figure 1. (A) Examples of CD42b + (red)/CD34 + (green) conjugates formed after stimulation with RFYVVMWK observed by confocal microscopy. Scale bars: 5 µm. (B-E) Expression of CD47 (B), TSP-1 (C), CD62P (D), and CD162 (E) on CD34 + /CD42b + conjugates and CD34 + /CD42b -cells after RFYVVM or RFYVVMWK preconditioning. TSP-1, thrombospondin-1; MFI, mean fluorescence intensity; T2D, type 2 diabetes (gray bars); non-T2D, nondiabetic (white bars); NS, not significant. *p < 0.05; **p < 0.01; ***p < 0.001 [analysis of variance (ANOVA)].

Figure 2 .

 2 Figure 2. Expression of CD29 (A) and CD51/CD61 (B) on CD34 + /CD42b + conjugates and CD34 + /CD42b -cells after RFYVVM or RFYVVMWK preconditioning. (C) Examples of CD29 (top) and CD51/CD61 (bottom) distribution on RFYVVM (left)-and RFYVVMWK (right)-stimulated cells observed by confocal microscopy are shown. MFI, mean fluorescence intensity; T2D, type 2 diabetes (gray bars); non-T2D, nondiabetic (white bars); NS, not significant. *p < 0.05; **p < 0.01; ***p < 0.001 (ANOVA).

Figure 3 .

 3 Figure 3. Percentage of CD34 + annexin V + /PI -and annexin V + /PI + cells after preconditioning with RFYVVM or RFYVVMWK. T2D, type 2 diabetes (gray bars); non-T2D: nondiabetic (white bars); AnV, annexin V; PI, propidium iodide. **p < 0.01; ***p < 0.001 (ANOVA).

Figure 4 .

 4 Figure 4. Effect of peptide preconditioning on the adhesion of CD34 -and CD34 + cells onto vitronectin-collagen matrix. (A) All patients (diabetic plus nondiabetic). (B) Diabetic (gray bars) versus nondiabetic patients (white bars). Results are expressed as number of adherent cells per 2 ´ 10 3 seeded cells. ***p < 0.001 (Kruskal-Wallis test). Effect of preconditioning with TSP-1 peptides on the adhesion of CD34 + (nonhashed bars) and CD34 -cells (hashed bars) in diabetic (gray bars) versus nondiabetic patients (white bars) on HUVEC monolayers prestimulated by TNF-a (C) or IL-1b (D). Results are expressed as number of adherent cells per 10 3 seeded cells (p > 0.05, Kruskal-Wallis test). HUVEC, human umbilical vein endothelial cell; TNF, tumor necrosis factor; TSP, thrombospondin; T2D, type 2 diabetes; non-T2D, nondiabetic; NS, not significant. ***p < 0.001 (ANOVA).

Table 1 .

 1 Patient Characteristics

		Nondiabetics	Type 2 Diabetics
	Characteristics	(n = 20)	(n = 20)	p
	Age (years)	70.1 ± 1.9	69 ± 1.6	0.34
	BMI (kg/m 2 )	29 ± 1.1	30 ± 1.6	0.2
	Hypertension (%)	15 (75)	12 (60)	0.5
	Dyslipidemia (%)	19 (95)	19 (95)	1
	Former smoking (%)	12 (60)	15 (75)	0.46
	Active smoking (%)	2 (10)	2 (10)	1
	Blood glucose (mmol/L)	5.61 ± 0.1	7.9 ± 0.5	<0.001
	HbAIc (mmol/mol)	39 ± 0.9	51 ± 3.6	<0.001
	Total cholesterol (mmol/L)	3.8 ± 0.2	3.7 ± 0.2	0.7
	LDL cholesterol (mmol/L)	2 ± 0.2	1.8 ± 0.2	0.08
	HDL cholesterol (mmol/L)	1 ± 0.1	1.1 ± 0.1	0.8
	Triglycerides (mmol/L)	1 ± 0.1	1.8 ± 0.2	0.002
	Platelets (G/L)	199 ± 11.4	181 ± 6.3	0.3
	Statins (%)	20 (100)	20 (100)	NS
	Antiaggregant (%)	20 (100)	20 (100)	NS
	Oral antidiabetics (%)	0	18 (90)	<0.001

Results are expressed as means ± SEM. BMI, body mass index; HbA1c, glycosylated hemoglobin; LDL, low-density lipoprotein; HDL, high-density lipoprotein.

ACKNOWLEDGMENTS: This work was supported in part by

the Agence Nationale de la Recherche (Grant No. ANR-07-PHYSIO-025-02). The authors declare no conflicts of interest.


Odile Heddebaut
email: odile.heddebaut@ifsttar.frwww.ifsttar.fr

Floridea Di
email: floridea.diciommo@cambiamo.net

Ciommo Cambiamo | Changing Mobility

City-Hubs for Smarter Cities. The case of Lille "Euraflandres" Interchange. 1

Keywords: Multimodal interchanges, smart cities, stakeholder involvement, socio-economic impacts, urban planning, urban landmark, Euraflandres Pôles d'échanges multimodaux, smart cities, engagement des acteurs, impacts socioéconomiques, planification urbaine, repère urbain, Euraflandres

Good planning and organization of communication and transport networks contributes to the development of cities that are more fluid and user-friendly and sustainable. All these attributes are included in the concepts underlying "smart cities". The efficient operation of the nodes located at these transport networks is a condition to make the city smarter. As part of the European research project FP7 "City-HUB", 27 interchanges have been studied in nine European countries. The key question to answer was how they function concerning the planning governance and the installations organisation. One of the main results of this research project has been the elaboration of a City-HUB typology that will be used to analyse the upcoming "Euraflandres" interchange transport node within the Métropole Européenne de Lille (MEL). The two adjacent "Gare Lille Flandres interchange" and "Gare Lille Europe interchange" will be integrated in a unique City-HUB named "Euraflandres". We demonstrate that the combination of transportation and urbanism policies within a transport node could stimulate local development, contribute to a sustainable and user-friendly city. The new pole of urban exchanges "Euraflandres" would overcome the pure role of transport infrastructure to become a "place" of life and the urban landmark for a smart city within the Métropole Européenne de Lille.

RÉSUMÉ

Une bonne planification et organisation des réseaux de communication et de transport contribue au développement de villes plus fluides, conviviales et durables. Tous ces attributs sont inclus dans les concepts sous-jacents des «smart cities». Le fonctionnement efficace des noeuds situés sur ces réseaux de transport est une condition pour rendre la ville plus intelligente. Dans le cadre du projet de recherche européen FP7 "City-HUB", 27 pôle d'échanges ont été étudiés dans neuf pays européens. Comment ils fonctionnent du point de vue de la gouvernance et de l'organisation des installations fut la question centrale de ces travaux. Un des principaux résultats de ce projet de recherche a été l'élaboration d'une typologie pour les City-HUB qui servira à analyser le futur pôle d'échange «Euraflandres» au sein de la Métropole Européenne de Lille (MEL). Les deux pôles d'échanges adjacents «Gare Lille Flandres» et «Gare Lille Europe» seront intégrés dans un futur City-HUB unique baptisé «Euraflandres». Nous démontrons que la combinaison des politiques de transport et d'urbanisme dans un noeud de transport pourrait stimuler le développement local, contribuer à une ville durable et conviviale. Le nouveau pôle d'échanges urbains "Euraflandres" permettrait de dépasser son pur rôle d'infrastructures de transport pour devenir un "lieu" de vie et un repère pour une « smart city » comme Lille au sein de la MEL.

INTRODUCTION & BACKGROUND

In the call for papers for the European transport research review (ETRR) special issue on "smart cities and transport infrastructures", the editors stipulate that "smart cities are concerned with new consideration towards environment, such as new ways for consuming and producing clean energies through mobility, oriented with new uses of information, but also better interconnection of networks, including transport means and infrastructure" [START_REF] Carnis | European Transport Research Review, Proposal for a topical collection on "Smart cities and transport infrastructures[END_REF]. This article tries to answer a key question: how an integrated and land mark transport interchange contributes to a smarter, more sustainable and friendly city? What is the role of public transport network connections to increase the use of eco-friendly transport modes? Within this context the paper focuses on the conception of intermodal transport infrastructures such as city-hubs and on their contribution to enhance urban mobility. This having an impact on smart cities environmental and quality of life aspects. After a literature review on the smart city concepts from technological, people and communities points of view (section 2), section 3 presents the evolution of the interchanges definition and their spatial organisation. We develop the idea that City-HUB interchanges are inducing new and smarter practices of transport infrastructure(s). In particular, the organisation of transport networks in City-hubs, associated with their fluidity, their comfort and their eco-friendly characteristics plays a key role within a Smart City. This section presents how the City-HUB interchanges typology works to rank transport interchanges and create a smart and eco-friendly urban environment. Section 4 is dedicated to the interchange case study of the Métropole Européenne de Lille (MEL) where two adjacent interchanges, "Gare Lille Flandres Interchange" and "Gare Lille Europe Interchange", are becoming a potential unique interchange named "Euraflandres". We describe its location as a node within the regional, national, and international railway networks, its socio-economic, spatial organisation and governance. In the conclusion (section 5) we present the main findings of our research work.

LITERATURE REVIEW ON SMART CITIES AND CONSIDERATION OF TRANSPORT DIMENSION

The smart city concept from a technological point of view

At the end of 90's the accent was put on technical aspects and particularly on the ICT (Information and Communication Technologies) to define smart cities (Harrison, Donelly, 2011).

Technology for smart cities is described by [START_REF] Washburn | Helping CIOs Understand "Smart City" Initiatives: Defining the Smart City, Its Drivers, and the Role of the CIO[END_REF] as "smart computing". Smart computing refers to "a new generation of integrated hardware, software, and network technologies that provide IT systems with real-time awareness of the real world and advanced analytics to help people make more intelligent decisions about alternatives and actions that will optimize business processes and business balance sheet results". [START_REF] Bertossi | Villes intelligentes, «smart», agiles, Enjeux et stratégies de collectivités françaises[END_REF] stressed the role of transport infrastructures in its capacity to contribute to the smart city as a "fluid", "intelligent" and "convivial" city. Intermodal city hubs are specific infrastructures that can combine these concepts by enhancing the mobility fluidity, the use of connected tools, and develop urban new neighbourhoods within the combination of transport and urbanism policies seeking conviviality and trying to enhance urban amenities for their citizens.

As explained by [START_REF] Albino | Smart Cities: Definitions, Dimensions, Performance, and Initiatives[END_REF], "cities worldwide have started to look for solutions which enable transportation linkages, mixed land uses, and high-quality urban services with long-term positive effects on the economy. For instance, high-quality and more efficient public transport that responds to economic needs and connects labour with employment is considered a key element for city growth".

In its paper on smart cities, the European Parliament (2014) counts smart mobility as a fundamental component of smart cities with smart governance, smart economy, smart environment, smart people and smart living. "By Smart Mobility we mean ICT supported and integrated transport and logistics systems. For example, sustainable, safe and interconnected transportation systems can encompass trams, buses, trains, metros, cars, bicycles and pedestrians in situations using one or more modes of transport". Moreover, it insists on the interaction between stakeholders. "Smart Mobility prioritises clean and often non-motorised options. Relevant and real-time information can be accessed by the public in order to save time and improve commuting efficiency, save costs and reduce CO2 emissions, as well as to network transport managers to improve services and provide feedback to citizens. Mobility system users might also provide their own real-time data or contribute to long-term planning ((European parliament, 2014, p.28)".

The necessity to combine urban planning and smart cities initiatives is also stressed by Anthopoulos and Vakali, (2016) who examine their interrelations and reciprocities between these policies.

The smart city concept from the involvement of people and communities

Transport infrastructures are also seen as a means to contribute to smarter a city and provide its inhabitant with a better quality of life. The review of literature made by [START_REF] Albino | Smart Cities: Definitions, Dimensions, Performance, and Initiatives[END_REF] shows that there is a need to reintroduce organisation, and "look at people and community needs".

For [START_REF] Chourabi | Understanding smart cities: an integrative framework, 45 th Hawaii International Conference on System Science.Batty et al; Smart cities of the future Eur[END_REF] infrastructures that contribute to smarter cities are seen as technical ones such as wireless infrastructure (fibre optic channels, WI-Fi networks, wireless hotspots), and serviceoriented information systems. But they determine eight critical factors such as management and organisation; technology; governance; policy context; people and communities; built infrastructure and natural environment to understand smart cities. When describing one of these factors particularly important related to people and communities, they count accessibility to provide an impact on citizen's quality of life. Nam and Pardo (2011a) firstly made a literature review to understand the common multidimensional components underlying the smart city concept. They describe a smart city as "an organic connection among technological, human and institutions components". They provide a scheme linking these three factors nourishing the vision of a smart city including smart transportation. They affirm that "social factors other than smart technologies are central to smart cities". When defining smart cities concepts from a technological point of view they say that "ITS can help people make more intelligent decisions about alternatives".

In a new publication, [START_REF] Nam | Smart city as urban innovation: Focusing on Management, Policy and context[END_REF] insist on the fact that "smart is more user-friendly than intelligent which is limited to having a quick mind and being responsive to feedback. A smart city is required to adapt itself to the user needs and to provide customised interfaces". They conclude that "a smart city is not only a technological concept but a socioeconomic development one, service oriented. It is a "new concept of partnership and governance developed through electronic linkage of multi-level, multi-jurisdictional governments and all non-governmental stakeholders such as firms ... and citizens".

METHODS TO DETECT CITY-HUBS ROLE IN A SMART CITY

Evolution of interchanges' definitions

As seen above, smart mobility and good use of transport infrastructures contribute to smarter the city. Intermodal transport interchanges are specific infrastructures enabling this smart mobility.

In this section we demonstrate that the definition of interchanges evolves from a purely functioning one describing the ease of movement inside and outside the interchange towards its integration into a more complex vision of its different interactions with transport, service and city functions. Furthermore it describes how they provide better citizen's quality of life by linking institutional, governance, and socioeconomic development within the urban context.

A clear definition of interchange was elaborated by the Madrid Regional Transport Authority in 1985 with a vision of making them accessible, working and convenient i.e.: an "Area whose purpose is to minimize the inevitable sensation of having to change from one mode of transport to another, and efficiently using the inevitable waiting time" [START_REF] Crtm | Plan de Intercambiadores Madrid[END_REF].

Public transport hubs in many European cities are often designed for different scale functions. [START_REF] Richer | L'émergence de la notion de « pôle d'échanges » : entre interconnexion des réseaux et structuration des territoires[END_REF] describes the three functions of an interchange. He associates the transport function enhancing the mobility fluidity using smart transport services with the city function combining city and land planning, the neighbourhood development and new territorial polarisation, providing city services. The service function represents services that concern the different domains of the previous functions. Source: [START_REF] Richer | L'émergence de la notion de « pôle d'échanges » : entre interconnexion des réseaux et structuration des territoires[END_REF] They can also provide new functions and determine new roles for national rail and road network accessibility, creating new hierarchies within cities. They can have a very important function within the regional planning context providing new urban centralities as explained in section 5.1. Multimodal poles are also integrated into urban and local land planning. They can produce urban regeneration of some areas and be part of a transit oriented development (TOD) policy [START_REF] Calthorpe | The Next American Metropolis: Ecology, Community, and the American Dream[END_REF][START_REF] Cervero | Transit-oriented development and joint development in the United States: A literature review[END_REF] The ultimate function of an interchange is to easily transfer from one mode of transport to another. The main idea is to facilitate intermodal transfers, increase the sustainable transport mode use, and reduce the total journey time, improving the quality of service. Interchange nodes are oriented to coordinate various private and public modes

Spatial organisation within the interchanges

Di [START_REF] Di Ciommo | Using hybrid latent class model for city-HUBs´users behaviour analysis[END_REF] show that users identify the improvement of city-hubs with the quality of time spent inside. The current challenge of interchanges is to facilitate transfer from the use of private motorized vehicles to a shared use of cars (i.e. car sharing or carpooling), to the use of public transport, and non-motorized modes. It is, in a certain way, a planning principle. A comfortable and practicable connection by platforms, information systems, bike and ride options, and pedestrian flows organization around an interchange, will be the pivot for designing, constructing and renewing interchange spaces. Travel intermodality could become a real policy goal to provide passengers with seamless journeys even when they use a combined trip chain.

It is essential to make interchanges attractive places in order to reach or maintain a good level of public transport use. As travel patterns become more complex, currently many public transport users have to make transfers between different transport modes to complete their daily journeys. In this respect, measures oriented to improve public transport service quality are required, such as reducing the transfer inconvenience and providing a seamless travel experience. Moreover, total travel time directly influences trip choices. Good connectivity at public transport stops and stations is therefore critical to overall transport network effectiveness [START_REF] Iseki | Style versus Service? An Analysis of User Perceptions of Transit Stops and Stations[END_REF]. Urban transport interchanges play a key role within transport network since they allow that different modes can be used in an integrated manner. However, transport stations in general must be considered multimodal facilities where travellers are not only passing through; they are also spending time there [START_REF] Van Hagen | Waiting experience at train stations[END_REF]. For this reason, public transport users are particularly affected by the quality of the service provided.

The European "City-HUB" project investigated how transport interchanges work from the point of view of governance and the organization of facilities. This project has determined a number of relationships between transport infrastructure such as multimodal interchanges and their environment. A good link between transport functions and urbanism planning provides efficient use of urban spaces, especially in city centres where there is scarcity of space and where multiple types of trips coexist. The social link represents the necessity to deploy inclusive mobility where persons with special needs could access the transport modes at a fair price. Developing strategic governance between planners, policy makers, operators and the business world ensure a good functioning of these city interchanges. The technical link develops innovations and can change user's habits by implementing intelligent transport systems (ITS) and nomad technologies like itinerary devices on smart phones.

The aim of an interchange will generally be oriented to improve the quality of public transport services and support seamless door-to-door travel. But nowadays an interchange is more than a simple node in a transport network; it includes many elements. Research literature shows that the benefits of urban interchanges relate to time savings, better use of waiting times, urban integration, and improved operational business models [START_REF] Di Ciommo | L'accessibilité: l'enjeu prioritaire de la nouvelle politique des transports publics à Naples, in Bernard Jouve, Les politiques de déplacements urbains en Europe[END_REF]. Besides accessibility improvements, management, and innovation, an efficient use of interchanges should also be considered. It also concerns the urban environment related to its impacts on the land use or constraints by the land use around the interchange. On this basis, we defined a typology of interchanges to classify those interchanges and select the key elements to improve the interchanges location, construction, and organisation.

Scoring interchange weight

These different functions as described above can be applied to interchanges that present particular dimensions and sizes. On the basis of the 27 analysed interchanges in the City-HUB project we have established a typology capturing different interchanges and a scheme for scoring their characteristics in terms of function and logistic dimensions (demand, number of transport modes, services and facilities, location in the city) and their local constraints [START_REF] Di Ciommo | Interchange place in Monzon-de[END_REF]. In particular, the first group of aspects (Dimension A) is related to the internal functions and logistics of an interchange, including transport elements of the interchange and the services and facilities necessary to fulfil the transfer functions properly. This dimension determines the size of the terminal building. The second group (Dimension B) includes the external aspects of the city environment that affect how the building could be in reality. This dimension includes the location of the interchange within the city and whether or not the interchange plan is in conflict with the existing land uses in the surrounding area, and if a specific development plan exists for the area of the interchange or for the interchange in itself. The values given in Dimension A determine the need for space: interchange size. Total score lower than 4 require a Small interchange. Scores 5-7 indicates the need for a Medium one, while higher than 8 means that the interchange should be rather big, becoming an urban Landmark. Dimension B aspect could be negative, positive or neutral, modifying in this way the previous scores and the type of required interchange.

This typology is applied to analyse the "Euraflandres" interchange case study in section 4.5 when questioning its potential to become an urban landmark.

The interchange governance framework

Once the typology of an interchange and urban planning has been defined, the second relevant aspect is its managing and the regulation behind governance. Following the developed analysis for the City-HUB cases studies, the governance framework is specified through carrying out semistructured interviews with key interchange actors (Popelier et al., 2016).

The co-ordination of modes is related to the involvement of different stakeholders in a common governance framework to plan interchange practices and urban space with an urban sustainable scope. The friendly use of these interchanges by citizens is also a goal to attain and new technologies can be deployed in the context of smart cities, such as on-time information, free access networks for mobility purpose but also providing new public spaces and urban facilities.

Despite existing barriers (complex governance framework, physical barriers, functions and logistics to revise, local constraints), all the stakeholders are willing to improve the visibility and the functionality of these interchanges. The city-HUB project shows how the urban interchange has the role of developing activities and regenerating the urban environment, by transforming the surrounding area features. All this will make cities more convivial and fluid, answering per se at least to two key aspects of smart cities: the fluidity and the conviviality (see, the definition of a smart city as a "fluid", "intelligent" and "convivial" by [START_REF] Bertossi | Villes intelligentes, «smart», agiles, Enjeux et stratégies de collectivités françaises[END_REF].

THE CASE STUDY OF THE "EURAFLANDRES" : A POTENTIAL URBAN LANDMARK?

In this section, we need to precise some definitions of used names. "Gare Lille Flandres" means the "Gare Lille Flandres" railway station. "Gare Lille Flandres Interchange" means the interchange composed of the "Gare Lille Flandres" railway station and the metro and tramway stations bearing the same name linked with the other public transports such as buses, public bike sharing named V'Lille and public car-sharing system named Lilas. The same distinction occurs for the "Gare Lille Europe" that is the international railway station and the "Gare Lille Europe Interchange" that combines the entire urban public transports, including international trains, and the future private coaches station (Eurolines, SNCF interurban coaches, ...).

"Euralille" is the name of the shopping mall that is located between the "Gare Lille Flandres Interchange" and the "Gare Lille Europe Interchange".

"Euralille" is also the name of the new business centre created at the end of the 90' at the occasion of the Northern TGV network achievement. In the literature it is also named "Euralille 1" or the CIAG (Centre International d'Affaires des Gares). We will call it the "Euralille CBD (central business district)".

"Euralille 3000 project" is the name of the future "Euralille CBD" development project until the year 2030.

"Euralille spl" is the name of the company in charge of the "Euralille CBD" development.

"Euraflandres" is the future name of the bigger interchange. It will include the "Gare Lille Flandres Interchange", the "Gare Lille Europe Interchange", the "Euralille" shopping mall and the "Euralille CBD".

The place of the "Euraflandres" interchange as a node on networks

The main reason to develop a joint interchange as a unique node is to reduce car dependency and increase public transport use. Effectively we describe in section 4.5 how "Euralille CBD" is the result of political willingness of combining railway infrastructure investment and urban public stations on a high speed railway network and the creation of a completely new business and commercial district.

In February 2016, the MEL published its new document for planning and sustainable development of its land use Scheme of Territorial Coherence (SCOT). For the first time the SCoT, introduces the city-HUB of "Euraflandres" as the linkage of the two interchanges of "Gare Lille Flandres Interchange" and "Gare Lille Europe Interchange" in relation with the new district of Euralille CBD [START_REF] Mel | Projet d'aménagement et de développement durables du SCOT de Lille Métropole[END_REF]. In January 2017, various interviews were conducted with "Euraflandres" stakeholders in order to understand the transformations and evolutions that are projected within the MEL interchanges of "Gare Lille Flandres Interchange" and "Gare Lille Europe Interchange" to become "Euraflandres".

In this SCoT planning document, the name of "Euraflandres" appears and is put forward to affirm its role as the gateway to the MEL. "In the centre of the MEL, the railway stations "Gare Lille Europe" and "Gare Lille Flandres" associated with urban transport constitute a real transport hub. "Euraflandres" is a key nerves centre for travels and must be an attractive, readable and radiant pole serving the users and the overall image of the territory" (MEL, 2016).

"Euraflandres" is located at a hub on the regional, national and international high speed train rail network linking France to the United Kingdom, the Netherlands, Germany, and Belgium. This new position on the international high speed railway network created new centrality for Lille. Effectively, Lille, which was previously at the end of the French networks, being placed at the crossroad of the Northern high speed train network changed its role. Lille has become more central within the European transport network, in connection with different sub-regional areas with access to regional trains and intercity buses (figure 3).

As explained in the SCoT document, "Euraflandres" will be composed of two main interchanges in the MEL: "Gare Lille Flandres interchange" and "Gare Lille Europe interchange". They are located 500 metres from each other in the "railway stations triangle" and offer possibilities to transfer from urban public transports to rail services at the mainly regional level for the "Gare Lille Flandres" railway station and the mainly national and international level for the 'Gare Lille Europe" railway station. A big shopping mall is located between these two interchanges (figure 4). It is located in the centre of the new business district of "Euralille CBD" and bears the same name of Euralille. The Euralille shopping mall is 67,000 m² and includes 164 shops and services of which one is a hypermarket. 4.2 Spatial organisation within the future city-HUB of "Euraflandres"

The "Gare Lille Flandres interchange" is composed of the railway, metro and tramway stations bearing the same name of "Gare Lille Flandres". The "Gare Lille Flandres" Railway Station is an old construction inside the city very close to the main square, and near the old part of Lille. This station opened in the 19 th century in 1848. Its façade is the previous "Gare du Nord" from Paris that was reconstructed in Lille in 1867. It is the second regional train traffic station in France after Lyon. The "Gare Lille Flandres" railway station serves the regional towns with regional trains named TER (Express Regional Trains). It also links in one hour Lille to Paris with direct TGV trains.

"Gare Lille Flandres" railway station counts 17 platforms for more than 500 trains per day and has a traffic of 20 million passengers per year (2012) and 110,000 daily users of which 70,000 take the train and 40,000 are only crossing, using services or going into its shops. It has a lot of connexions with the urban transport network with the metro VAL (light automated vehicule) line 1 and line 2 (located underground second level), two tramway lines towards Roubaix and Tourcoing (at intermediate level) (see figure 1). Since the refurbishment of "Gare Lille Flandres" railway station, other shops have opened such as a sport bike-based shop, a supermarket and restaurants.

The "Gare Lille Europe interchange" is composed of a very modern railway station, metro and tramway stations bearing the same name of "Gare Lille Europe". The railway station was constructed to host the Northern high speed trains (French TGVs, Eurostars and Thalys) on the high speed railway network (see figure 1) and urban public transport station. It also serves regional high speed trains named TER-GV. These trains run on the high speed tracks to link the "Côte d'Opale" coastal area and the cities of Calais, Dunkirk, Boulogne sur Mer until Rang-du-Fliers at the South West of the region.

In order to facilitate moving between different means of transport for passengers, in the two railway stations a new color-coded information is used to display information: in blue, information about railway services (platform number); in green, information about the intermodal transport modes (metro, tramway, buses, taxis, self-service bikes, car-sharing, …) in yellow, information about services (ticket sales counters, waiting rooms, meeting points, toilets, …). It has been tested for the first time in the "Gare Lille Europe" railways station and is now applied in all the French railway stations in order to provide the same travel information and ease the passenger's trips inside the interchanges. This new colour code can be seen inside the two railways stations on figure 4.

Innovations have been made for fares and ticketing information with the new "PassPass" smart card information and ticketing. On-time information displays for train departures are located in the railway stations and in the "Gare Lille Flandres" metro station; in the O'Conway pub and in coffee shops in the "Gare Lille Europe" railway station. Nevertheless there is nearly no transport information in the Euralille shopping mall. A new "mobility agency" the "Pass Pass Boutique" gives information on the public transport network and sells special subscription cards (for students, schoolchildren, etc.) at the "Gare Lille Flandres" railway station. It also sells tickets for either urban trips on urban public transport network or railway trips on the TER regional passenger's network. This "Pass Pass Boutique" is the result of good governance between the different stakeholders allowing the share of transport data.

Intelligent transport supports the improvement of the quality of life in the city, while it offers tools for traffic monitoring, measurement and optimization (Anthopoulos and Vakali, 2016). An application provides real time information inside the "Gare Lille Flandres" railway station for all the MEL urban buses departures. This necessitates good coordination and sharing on data between the railway and urban public transport operators. Here is displayed the fluidity of travels and comfort of passengers that contribute to the concept of smart cities.

The smartness of use of these interchanges is provided inside the interchanges. Information to travellers is provided on the Internet and smartphones; there is an intermodal map with the location of each transport mode; free-of-charge and unlimited Wi-Fi access. Inside the two interchanges there are facilities such as new tickets purchase machines, new waiting lounges with special lounges for the "grand voyageurs" loyalty programme members, coffee shops and pubs, press kiosks, left-luggage service, toilets.

They also offer new facilities: Wi-bike (biking plugs), children's area in the concourse and free use pianos that contribute to a pleasant ambiance. On figure 4 (left) we see that the interchange is used by people that are not travelling but who want to benefit from the facilities such as tables equipped with plugs, free Wi-Fi, and it looks like a "café" ambience with shops surrounding the travel facilities. This show that interchanges become places to meet and live in the city.

4.3 Spatial organisation outside "Gare Lille Flandres Interchange" and "Gare Lille Europe interchange"

"Gare Lille Europe Interchange" and "Gare Lille Flandres Interchange" are offering numerous transport modes to access and egress the two railway stations bearing the same name. They are close to regular bus routes and one specific bus route the Citadine serves them on a circular route inside Lille. Twelve bus routes stop at the "Gare Lille Flandres interchange" exits and seven bus routes and long-distance coaches stop at the "Gare Lille Europe interchange". Self-service bikes in free access stations named V'Lille are placed near the two interchanges' main exits and a supervised bike garage which is free-of-charge for public transport passengers and train users is located at "Gare Lille Flandres interchange". For these two interchanges paid parking facilities exist.

Located between the two interchanges, a special "shuttle" bus links the Lille airport and another one the Charleroi airport in Belgium. Car-sharing possibility is offered at "Lille Flandres Interchange". The "Gare Lille Flandres" railway station passengers mainly come from the metro (44%) or tramway (4%) and flows are mainly coming from the underground access; or are walking or cycling (35%). The facts that there is a supervised free of charge garage for private bikes eases the use of that non-motorised mode. The "Gare Lille Europe" railway station passengers mainly come by car and taxis (42%) or metro and tramway (31%). In figure 5 we have regrouped the metro and tramway figures because tramway access trips to the railway stations are very low. We notice the differences in access modes for the two railway stations. This could be explained by travel motives. Effectively in "Gare Lille Flandres" railway station, there is more travel for work or study motives. The free access garage for private bikes could explain the cycling practice. In "Gare Lille Europe" railway station there is more travel for leisure or business motives that could explain partly the importance of access by cars or taxis. Daily travellers taking the TGV for work, can park their cars underneath this railway station and access directly to the platforms to take their trains.

There is a big issue for these interchanges to make possible the modal shift to public transport modes.

"Euraflandres": a city-HUB typology implementation

Urban policy plays an important role in shaping and changing the regional, national and even global linkages of cities. As described by [START_REF] Nam | Smart city as urban innovation: Focusing on Management, Policy and context[END_REF] coordination of policies-across a variety of spatial scales, across organizational practices, and across all levels of governance-is of vital importance to innovation in a city. They remark that "integration is not merely for technologies, systems, infrastructure, services or information but for policies". Governance involves the implementation of processes to share information and set up policies and actions to develop common projects [START_REF] Chourabi | Understanding smart cities: an integrative framework, 45 th Hawaii International Conference on System Science.Batty et al; Smart cities of the future Eur[END_REF].

Within the Lille metropolitan area, transport services' implementation is under the responsibility of different transport authorities at different institutional scales (national, regional and local). The regional express trains (TER) supply (investments, timetables, frequency, quality of service …) is ordered and financed by the Hauts de France regional Council. It is composed of TER trains in "Gare Lille Flandres" railway station and TER-GV (High speed TER) in "Gare Lille Europe" railway station. The urban public transport modes are operated by Transpole (Keolis) and the the MEL is the public authority for urban transport. The MEL elaborates urban sustainable mobility plans (SUMP) to enhance its inhabitants' mobility [START_REF] Lmcu | Euralille 3000 -Bilan de la concertation préalable-arrêt du projet et lancement de la procédure de déclaration de projet[END_REF]. The railway stations are run by Gares & Connexions and "SNCF-mobilités" is the rail operator. The tracks are under the property of previously RFF (Réseau Ferré de France) that became "SNCF Réseau" on 1 st July 2015. In the "Gare Lille Europe" railway station, national trains are scheduled and operated by "SNCF-mobilités" and international trains belong to the Railteam Company (SNCF, Eurostar, Thalys…).

All these different stakeholders meet regularly in common committees in order to provide better supply and services to passengers and citizens. As seen above, the joint "Pass Pass Boutique" is the result of a good cooperation and governance between transport authorities and operators at these different scales in order to share data, give information and purchase possibilities in the same site. This contributes to ease and facilitate passenger's trips. Joint committees are also organised between these previous stakeholders and other policy makers in urbanism and business domains. All this, to say that the governance issue for the possible "Euraflandres" interchange is complex to understand and operatively to manage.

We have conducted interviews in 2017 to understand the "Euraflandres" interchange's development as a MEL landmark.

We met the political and decision makers, the MEL's transports, roads and urbanism directors. They are in charge of planning transports' investments and organisation within the MEL urban public transport territory. They consider the future "Euraflandres" interchange achievement as a priority to ease the inhabitants and visitors' travels and accessibility. The Haut de France' TER service responsible plans and organises the TER supply and is in charge of investments in the regional railway stations. He supervises the future "Euraflandres" interchange accessibility by trains.

The City of Lille director for circulation organisation plan was implemented in August 2016 with three loops that serve the "Euralille CBD" but cars can no more cross it.

The Keolis operator Transpole services told us how they were reorganising the urban public transport access in the vicinity of the future "Euraflandres" interchange.

The regional railway stations director received us to show the transformations undertaken inside the "Gare Lille Flandres" and "Gare Lille Europe" railway stations in cooperation with the other stakeholders involved in the future "Euraflandres" development.

The "Euralille spl" director told us that they are willing to develop the "Euralille CBD" with a greater consideration of the neighbourhood quality of life and give its inhabitants more urban facilities such as restaurants, cafés, and leisure facilities. The facility/estate owners and/or estate companies who are in charge of the construction and maintenance of the interchange were also questioned about the role of interchanges in local economies and their potential impact on that.

They all together work in order to realise the renewing of the two interchanges. Within the "Gare Lille Flandres interchange", a first refurbishment was made in 2008 for the "Gare Lille Flandres" metro and tram stations. The "Gare Lille Flandres" railway station is under refurbishment since 2013 with works on the tracks for a better train supply. Since 2014 further infrastructural work were undertaken to provide new concourse, new joint Public Transport and rail ticket office (purchase of rail and/or public transport tickets, joint information, network maps, etc.). These works will also give a wider access to public transports, linking the ground floor level with bus access to underground levels where are located the "Gare Lille Flandres" tramway station and underneath the "Gare Lille Flandres" metro station. The first two floors of the railway station will be converted into a new 1,300 m² business centre with commercial and office spaces. The refurbishment budget is €18 million (in € 2013). It is shared between SNCF Gares & Connexions (€14,019,862), Nord Pas-de-Calais Region (€2,000,000), European Union (€1,320,138), the State (€660,000) and the City of Lille (€115,500).

According to the stakeholders' interviews, the "Gare Lille Flandres interchange" and "Gare Lille Europe interchange" refurbishment occurred after identifying the needs of the operators and clients. They also consulted the reduced mobility persons association. Moreover, the "Gare Lille Flandres" railway station stakeholders have set up discussion groups for the operation of the 13 regional TER routes involving elected members, operators and passengers for resolving problems and enhancing travel quality.

The SNCF director who is in charge of the two "Gare Lille Flandres" and "Gare Lille Europe" railway stations said during our interview that "before the railway stations were considered to be places where we took the train and it is everything with just a waiting room and a few services. There is nowadays a strong expectation of customers before taking the train to be able to get more services and shops. The second aspect is to include the railway station in the city. From this point of view, there are several functions which the railway station must complete: there is a function for connecting to different modes of transport. There is also an ambition to offer shops to the inhabitants of the district, a range of restaurants. So it's really a willingness to see the railway station as being an address in the city, really turned outwards and not towards the platforms".

4.5

The future "Euraflandres" interchange as a city-HUB landmark

Based on the typology described in section 3.3, the "Euraflandres" interchange gets a score of 9 because its demand is higher than 120,000 daily passengers, includes 13 public and private transport modes (several PT (metro, tram and urban buses), long distance coaches, car and bike sharing, taxis and even bike taxis), and is located in the inner city centre in the new "Euralille CBD". It is the result of reflexions included into local plans of urban development such as the SUMP and SCoT documents and TOD definition. The "Euraflandres" interchange has all the characteristics for becoming an urban landmark for the city of Lille and the MEL.

As highlighted by [START_REF] Banister | Transport investment and the promotion of economic growth[END_REF] three conditions must be present in order to induce economic development.

1) The first condition is the existence of political willingness to implement complementary policies in order to provide a better environment, boost the transport investment and obtain economic development.

2) The second condition is the significant size of the transport investment. A new interchange must provide new accessibility and new connections between transport modes. 3) The third condition is the economic context. It must reach high quality of labour forces and present underlying dynamics economic externalities at a local, regional or national level.

These complementary conditions can be useful to implement a transport hub as the part of an overall larger integrated policy and/or plan aiming at (re)developing linked economic activities and urban function (re)development. Moreover they conclude that "policy design also has a crucial role in influencing and strengthening the potential impact of transport infrastructure investment on local economic development."

For the "Euraflandres" interchange, a huge urban development project "Euralille CBD" was created.

The political willingness, first condition for economic development, can be illustrated by Pierre Mauroy the President of the MEL and former Prime Minister. His, ambition was to modernise the Lille city centre by constructing an entirely new district "Euralille CBD" and he gave it the name of "tertiary turbine". It was constructed from a non aedificandi zone corresponding to the ancient walls of the city and military lands (Prevot, 2011). A political decision was taken to create a completely new neighbourhood named "Euralille" seen as an important factor of the new social and economic policy for the MEL. This new neighbourhood was firstly developed as a "complex of economic functions rather than a neighbourhood" [START_REF] Moulaert | Euralille: Large-Scale Urban Development and Social Polarization[END_REF].

The second condition for economic development and the landmark city-HUB label is a transport investment of significant size. In the context of the Channel tunnel (1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994) and the Northern high speed train network (1987)(1988)(1989)(1990)(1991)(1992)(1993) constructions, important urban investments were realised in Lille [START_REF] Heddebaut | La stratégie d'accompagnement transmanche dans le Kent et le Nord-Pas de Calais : entre contextes institutionnels spécifiques et temporalités décalées[END_REF].

As seen above, the "Gare Lille Europe" railway station of international dimension represents an investment of € 146 million (in 1994) and was planned to host the Eurostar trains from London to Paris and to Brussels. It also host the French TGV, High Speed Trains, linking the main French cities in different regions: eastwards (Strasbourg), south wards (Lyon and Marseille) westwards (Bordeaux and Toulouse) and the Brittany (Nantes and Rennes). All these TGV serve and stop at the international Charles de Gaulle airport [START_REF] Heddebaut | Does the "tunnel effect" still remains in 2016?[END_REF].

The third condition for obtaining economic development is the high quality of the labour force. The new jobs created in the "Euralille CBD" correspond to these criteria. They all belong to the tertiary sector with a high representation of commerce (46%) and high skilled jobs in data processing ((18%), insurances (13%) and finance (12%) (Figure 6). Based on the [START_REF] Banister | Transport investment and the promotion of economic growth[END_REF] three conditions to induce economic development we can summarise by saying that the strong political will, first condition, was personified by Pierre Mauroy, who convinced all the regional political stakeholders to develop a new neighbourhood in Lille. The sufficient size of the transport investment, second condition, is represented by the new "Gare Lille Europe" railway station and the successive refurbishments of the "Gare Lille Flandres interchange" (in the railway, tramway and metro stations). The high quality of labour force, third condition, is illustrated by the distribution of jobs in this new neighbourhood of "Euralille CBD".

Different phases have been realised providing this new "Euralille CBD" neighbourhood with housing for local population, local culture, conviviality, etc. The Euralille shopping mall was created between the two "Gare Lille Flandres interchange" and "Gare Lille Europe interchange". New office buildings and housing have been constructed in the vicinity of the "Euraflandres" interchange.

Further extensions are foreseen to enlarge the "Euralille CBD" under the "Euralille 3000 project". The finding after the different interviews with the stakeholders shows that there is a greater ambition in Lille. To link transport and land-use planning, all of the planning stakeholders are involved in a Metropolitan development view (the regional council in charge of the regional planning and regional express trains development, the City of Lille, the Nord Département, the MEL that is the urban transport authority, the SNCF and Transpole the transport operators and Euralille Spl in charge of developing this area [START_REF] Heddebaut | Multimodal city-hubs and their impact on economic and land use planning[END_REF].

Three development areas are still under construction within the actual "Euralille CBD". Euralille 1 or the CIAG international centre for businesses included into the future "Euraflandres" interchange, and two other developments zones a little further, but linked to the two railway stations by the metro line 2 as explained during the Euralille Spl Director's interview.

Two other development projects are under construction [START_REF] Estienne | Euralille, fiche projet, extrait du tome 3, POPSU, Plate-forme d'observation des projets et stratégies urbaines[END_REF]. The first one of 22 hectares constructed on the wastelands of the former Lille International Fair is called "Euralille 2" close to "Euralille CBD" and will create a neighbourhood called "inhabited wood" with 600 housing programme; offices and activities; the extensions of Lille Grand Palais the international congress centre and the headquarters of the Region and the implementation of 13,000 m² of public facilities (schools, nurseries, kindergartens, sports equipment). The second one called "Porte de Valenciennes" is a 18 hectares program creating 1000 housing units including 360 social housing (120 social rental and 240 free rental and accessions) carried by CMH and LMH that are companies for social housing development in the Lille metropolis. 30,000m² of offices and 6,600m² of businesses and shops are being constructed and a part of this land will be converted into public spaces and squares.

New coordinated planned actions are undertaken to make this development within the further development and enlargement of the "Euralille CBD" under the name of "Euralille 3000 project". The new interviews realised in 2017 explained how "Euraflandres" is becoming a city-HUB landmark taking into account the communities and residents desires to make a liveable neighbourhood.

"Euraflandres" is part of the "Euralille 3000 project". Two periods of consultation took place in 2013 and 2015 with the involvement and the participation of the MEL's citizens and "Euralille CBD" residents prior to the launch of the "Euralille 3000 project" in 2016. A MEL decision (2015) taken after this consultation stipulates that "the mobility project will aim to reorganise the flow of travel through traffic loops that will improve access conditions to "Euraflandres". It will allow the development of soft modes and protect the city centre from car flow. The future "Euraflandres" interchange will host new programs and refurbishment to make it more comfortable for residents and users of the various modes of transport present on the sector" (MEL, 2015).

There are nowadays 6,000 persons per day walking between the "Gare Lille Flandres interchange" and "Gare Lille Europe interchange". More pedestrian and bike lanes will be built. A new signage to find its way will be implemented. Urban parks will be set to offer a better connected neighbourhood networks.

Effectively, "this gateway must be prepared to accommodate 50% of additional passenger flow in the coming years. The urban project must also accompany these developments. The hub must maintain or improve its effectiveness. Not only accommodate more travellers but welcome them in better conditions (Euralille SPL, 2015)".

All this contributes to smarter the city by providing facilities to city-hub users as passengers but also to the MEL citizens and the "Euralille CBD" inhabitants. The "Euraflandres" interchange implementation is creating economic development in the MEL and moreover, following the City-UB typology, is becoming an urban landmark to smarter the city of Lille

CONCLUSION

We have seen that the opportunity of joining together the two "GareLille Flandres" and "Gare Lille Europe" interchanges in a unique interchange under the name of "Euraflandres" will contribute to build a great urban interchange. It will procure the advantage for increasing the accessibility for all destinations at urban Lille metropolis and regional levels, but also at the national and international levels by the possibility offered by the French TGVs running on national network and the Rail team high speed trains such as Eurostar and Thalys.

Each type of interchange, according to the identified functions and local constraints, should require the involvement of different interchange stakeholders. "Euraflandres" management with its stakeholders' committees seems to be oriented to make effort to find an agreement to reduce conflicts, in order to plan outcomes better and to allow communities to have an influence over the future shape of the places where they live. The community-led participation intended here [START_REF] Spl | Les échos de la concertation Euralille 3000[END_REF] is the first step to identify operators and users' requirements and needs (i.e. transport activities including services and facilities) and who will perceive "Euraflandres" as a transport node where to have access to their mobility mode and a place to carry out some other activities during their waiting time or leisure activities.

Following, the Stated Preference results of the City-HUB [START_REF] Di Ciommo | Using hybrid latent class model for city-HUBs´users behaviour analysis[END_REF]), a good interchange could increase between 7% and 20% the use of intermodal and public transport modes. The development of "Euraflandres" could attract additional public and active modes users with a real decreasing of car use that contributes to an eco-frienldly city. Further research is however required to measure the current participation of the "Euraflandres" customers and "Euralille CBD" residents to the smart city development even at metropolitan level with the MEL.

Actually the smart aspects of a transport interchange are deeply related with the modal shift, the environmental and health impacts, and the potential use of ITS for smooth intermodal changes. All these aspects are key characteristics for a city-HUB such as schedules consistency, the wayfinding, the use of the waiting time, the comfort during the waiting time, all aspects that make a City-HUB smarter and contribute to a smart city. This article has shown how "Euraflandres" potentially includes all these smart elements.

We have demonstrated that the "Euraflandres" interchange is able to induce economic development but also to play the role of developing activities and regenerating the urban environment, by transforming the surrounding area features. The extension of the "Euralille CBD" is part of the Lille urban regeneration and still under construction. It will provide new housing and also social housing for low incomes and new city amenities transforming it in a new place to live. The transformation of the two current separated interchanges towards "Euraflandres" will achieve a landmark interchange with a higher share of sustainable and affordable public transport modes share. All this will make Lille more convivial and fluid, two key aspects of the Smart City.

Figure 1 :

 1 Figure 1: The three functions of a city-hub.

Figure 2 :

 2 Figure 2: Place of the "Euraflandres" interchange in Lille within the French and international railway network.

Figure 3 :

 3 Figure 3: "Euraflandres": linking the "Gare Lille Flandres Interchange" and "Gare

Figure 4 :

 4 Figure 4: Inside the "Gare Lille Flandres interchange" (left) and the "Gare Lille Europe interchange" (right)

Figure 5 :

 5 Figure 5: Modal share of both "Gare Lille Flandres" and "Gare Lille Europe" railway stations.

Figure 6 :

 6 Figure 6: Distribution of jobs according to the sectors in the "Euralille CBD" area

Table 1 Interchange Dimensions: Function and Logistics, Local Constraints Dimension A Function and Logistics Levels Need for space Score

 1

			< 30,000	Low	1
	Demand (users/day)	30-120,000	Medium	2
			> 120,000	High	3
			Dominant -bus	Low	1
	Modes of transport	Dominant -rail	Medium	2
			Several modes and lines	High	3
			Kiosks, vending machines	Low	1
	Services and facilities	Several shops and basic facilities	Medium	2
			Integrated shopping mall with all facilities	High	3
	Dimension B Local constraints		Levels	Upgrading level	Value
			Suburbs	Less	-
	Location in the city		City access	Neutral	O
			City centre	More	+
			Non-supporting activities	Less	-
	Surrounding features	area	Supporting activities	Neutral	O
			Strongly supporting activities	More	+
			None	Less	-
	Development plan		Existing	Neutral	O
			Existing and including intermodality in the area	More	+

Source

: Di Ciommo et al., 2016

  It opened in 1994 with the opening of the Channel tunnel and the northern TGV network. It also serves the other French regions by TGV trains that go directly to the South East (Lyon, Marseille, Nice), or the East (Strasbourg). It connects the Western parts of France (Brittany to Nantes, Rennes, and South West to Bordeaux…) by means of trains that go around Paris and after westwards. All the TGVs stop at the international airport of Roissy Charles De Gaulle when going southwards. The "Gare Lille Europe" railway station counts 4 platforms and 2 central railway lines for Eurostar trains coming from Paris and going directly to London. It has a daily traffic of 8,500 passengers. It connects Lille to Paris by TGV (1 hour), and to Brussels (38 minutes) and London (1 hour 20 minutes) with the Eurostar trains. Since 2014 works have been undertaken on the departure concourse for the cross-Channel trains (Eurostar): it will provide new control desks, and a bigger boarding area.

Table 2 : Surfaces constructed and functions in "Euralille CBD"

 2

	M² of SHON*	Euralille 1	Further extensions
	Housing	138,000	+75,000
	Offices	240,000	+140,000
	Commerces	110,000	+30,000
	Hotels	28,000	+5,000

This article is part of the Topical Collection on Smart Cities and transport infrastructures