title: CD34 hybrid cells promote endothelial colony-forming cell bioactivity and therapeutic potential for ischemic diseases.
abstract: OBJECTIVE
  Although endothelial progenitor cells (EPCs) have been reported to promote neovessel formation during vascular injury, the function of supporting cells of EPCs and their interaction with EPCs during EPC isolation remain unclear.
  
  
  RESULTS
  We investigated the functional properties of 2 types of EPCs, also known as endothelial colony-forming cells (ECFCs), CD34(-)/CD34(+) cell-derived ECFCs (hybrid-dECFCs) and CD34(+) cell-derived ECFCs (stem-dECFCs), isolated using different methods, to elucidate the role of CD34(-) cell populations as cell-supporting niches. Using EPC colony-forming and insert coculture assays, we found that CD34(-) accessory cells dynamically modulate hematopoietic stem cell-derived endothelial cell progenitor commitment via angiogenic cytokines secreted by CD34(-)/CD11b(+) macrophages. On the basis of these findings, we isolated 2 types of ECFCs and investigated their bioactivities. We found that stem-dECFCs showed remarkably retarded cell growth, enhanced senescence, and decreased characteristics of ECFCs, whereas hybrid-dECFCs showed greater proliferative properties but delayed senescence. In a murine hind-limb ischemia model, hybrid-dECFCs showed significantly enhanced blood perfusion, capillary density, transplanted cell survival and proliferation, and angiogenic cytokine secretion compared with stem-dECFCs. In particular, the migratory capacity of hybrid-dECFCs was significantly enhanced, in part mediated via an augmented phosphorylation cascade of focal adhesion kinase and Src, resulting in a highly increased incorporation capacity of hybrid-dECFCs compared with stem-dECFCs. CD34(-) accessory cells of hybrid-dECFCs might be niche-supporting cells that facilitate cell survival, increase the secretion of angiogenic cytokines, and increase incorporation.
  
  
  CONCLUSIONS
  This study provided important insight into blood vessel formation and repair in ischemic diseases for ECFC-based cell therapy.
authors: Laboratory for Vascular Medicine and Stem Cell Biology, Medical Research Institute, Department of Physiology, School of Medicine, Pusan National University, Yangsan, Korea.
authors: Jun Hee
authors: JH
authors: Lee
authors: Sang Hun
authors: SH
authors: Lee
authors: So Young
authors: SY
authors: Yoo
authors: Takayuki
authors: T
authors: Asahara
authors: Sang Mo
authors: SM
authors: Kwon
mesh_terms: D042501:Angiogenic Proteins / Q000378:metabolism; D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D001783:Blood Flow Velocity; D002450:Cell Communication; D002454:Cell Differentiation; D019070:Cell Lineage; D002465:Cell Movement; D049109:Cell Proliferation; D002469:Cell Separation / Q000379:methods; D002470:Cell Survival; D016922:Cellular Senescence; D018920:Coculture Techniques; D003114:Colony-Forming Units Assay; D036101:Cord Blood Stem Cell Transplantation; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism* / Q000637:transplantation*; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D006614:Hindlimb; D006801:Humans; D006822:Hybrid Cells; D007511:Ischemia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D017078:Laser-Doppler Flowmetry; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D018482:Muscle, Skeletal / Q000098:blood supply*; D018919:Neovascularization, Physiologic; D010641:Phenotype; D020127:Recovery of Function; D012039:Regional Blood Flow; D055153:Stem Cell Niche; D013234:Stem Cells / Q000378:metabolism*; D013997:Time Factors; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D042501:Angiogenic Proteins; D018952:Antigens, CD34; D015415:Biomarkers; D016207:Cytokines; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019061:src-Family Kinases
keywords: CD34; endothelial progenitor cells; hind-limb ischemia; niche-supporting cells; vascular repair; vasculogenesis