title: Sphingosine kinase 1 expressed by endothelial colony-forming cells has a critical role in their revascularization activity.
abstract: OBJECTIVE
  Cell therapy based on endothelial colony-forming cells (ECFCs) is a promising option for ischaemic cardiovascular diseases. A better understanding of the mechanisms by which these cells promote revascularization remains a critical challenge to improving their therapeutic potential. We aimed to identify the critical mechanisms involved in the revascularization activity of ECFCs by using the paracrine properties of mesenchymal stem cells (MSC).
  
  
  RESULTS
  Conditioned medium from human bone marrow-derived MSCs (MSC-CM) increased the angiogenic activity of cord blood ECFCs in vitro (proliferation, migration, and pseudo-tube formation), the survival of ECFCs in mice (Matrigel Plug assay), and the capacity of ECFCs to promote the recovery of blood perfusion in mice with hindlimb ischaemia. Furthermore, the capillary density in ischaemic gastrocnemius muscle was significantly increased in mice transplanted with the ECFCs pre-treated with the MSC-CM. The enhancement of ECFCs activity involved the up-regulation of sphingosine kinase 1 (SphK1) expression and activity. The inhibition of SphK1 in ECFCs by using an inhibitor or a siRNA knockdown of SphK1 prevented the stimulation of the ECFCs induced by the MSC-CM. The improvement of ECFC activity by MSC-CM also involved the up-regulation of sphingosine-1-phosphate receptor 1 (S1P1) and a S1P/S1P1/3-dependent mechanism. Finally, we showed that the stimulation of ECFCs with exogenous S1P increased angiogenesis and promoted blood perfusion in hindlimb ischaemia.
  
  
  CONCLUSIONS
  The up-regulation of SphK1 and S1P-dependent pathways is critical for the angiogenic/vasculogenic activity of ECFCs. The identification of this pathway provides attractive targets to optimize cell-based therapy for revascularization in ischaemic diseases.
authors.affiliation: Aix-Marseille Université, Vascular Research Center of Marseille (VRCM), INSERM UMR-S 1076, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille Cedex 05, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Poitevin
authors.affiliation: Institut des Maladies Métaboliques et Cardiovasculaires, INSERM U1048, Université de Toulouse III, 1 Av Jean Poulhès, BP 84225,  31432 Toulouse Cedex 4, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cussac
authors.affiliation: Aix-Marseille Université, Vascular Research Center of Marseille (VRCM), INSERM UMR-S 1076, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille Cedex 05, France.
authors.forename: Aurélie S
authors.initials: AS
authors.lastname: Leroyer
authors.affiliation: Centre de Recherche en Cancérologie, INSERM UMR-1037, Université de Toulouse III, BP 84225, CHU Rangueil, 31432 Toulouse Cedex 4, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Albinet
authors.affiliation: Aix-Marseille Université, Vascular Research Center of Marseille (VRCM), INSERM UMR-S 1076, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille Cedex 05, France.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Sarlon-Bartoli
authors.affiliation: Aix-Marseille Université, Vascular Research Center of Marseille (VRCM), INSERM UMR-S 1076, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille Cedex 05, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Guillet
authors.affiliation: Aix-Marseille Université, Vascular Research Center of Marseille (VRCM), INSERM UMR-S 1076, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille Cedex 05, France.
authors.forename: Lucas
authors.initials: L
authors.lastname: Hubert
authors.affiliation: Centre de Recherche en Cancérologie, INSERM UMR-1037, Université de Toulouse III, BP 84225, CHU Rangueil, 31432 Toulouse Cedex 4, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Andrieu-Abadie
authors.affiliation: EA 4553: Individualisation des Traitements des Cancers Ovariens et ORL, Institut Claudius Regaud, 20-24 rue du Pont St Pierre, 31052 Toulouse Cedex 4, France.
authors.forename: Bettina
authors.initials: B
authors.lastname: Couderc
authors.affiliation: Institut des Maladies Métaboliques et Cardiovasculaires, INSERM U1048, Université de Toulouse III, 1 Av Jean Poulhès, BP 84225,  31432 Toulouse Cedex 4, France.
authors.forename: Angelo
authors.initials: A
authors.lastname: Parini
authors.affiliation: Aix-Marseille Université, Vascular Research Center of Marseille (VRCM), INSERM UMR-S 1076, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille Cedex 05, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Dignat-George
authors.affiliation: Aix-Marseille Université, Vascular Research Center of Marseille (VRCM), INSERM UMR-S 1076, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille Cedex 05, France florence.sabatier@ap-hm.fr.
authors.forename: Florence
authors.initials: F
authors.lastname: Sabatier
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D017077:Culture Media, Conditioned; D042783:Endothelial Cells / Q000166:cytology* / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D018919:Neovascularization, Physiologic; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D049349:Receptors, Lysosphingolipid / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D000081025:Sphingosine-1-Phosphate Receptors; D000099157:Sphingosine Kinase
chemical_list: D017077:Culture Media, Conditioned; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid; D013110:Sphingosine; D000081025:Sphingosine-1-Phosphate Receptors; D000099157:Sphingosine Kinase; C556330:S1pr1 protein, mouse; C501285:S1pr3 protein, mouse; C060506:sphingosine 1-phosphate
keywords: Cell therapy; Endothelial progenitor cells; Ischaemia; Mesenchymal stem cells; Sphingosine kinase 1