title: Human cord blood-derived AC133+ progenitor cells preserve endothelial progenitor characteristics after long term in vitro expansion.
abstract: BACKGROUND
  Stem cells/progenitors are central to the development of cell therapy approaches for vascular ischemic diseases. The crucial step in rescuing tissues from ischemia is improvement of vascularization that can be achieved by promoting neovascularization. Endothelial progenitor cells (EPCs) are the best candidates for developing such an approach due to their ability to self-renew, circulate and differentiate into mature endothelial cells (ECs). Studies showed that intravenously administered progenitors isolated from bone marrow, peripheral or cord blood home to ischemic sites. However, the successful clinical application of such transplantation therapy is limited by low quantities of EPCs that can be generated from patients. Hence, the ability to amplify the numbers of autologous EPCs by long term in vitro expansion while preserving their angiogenic potential is critically important for developing EPC based therapies. Therefore, the objective of this study was to evaluate the capacity of cord blood (CB)-derived AC133+ cells to differentiate, in vitro, towards functional, mature endothelial cells (ECs) after long term in vitro expansion.
  
  
  METHODS
  We systematically characterized the properties of CB AC133+ cells over the 30 days of in vitro expansion. During 30 days of culturing, CB AC133+ cells exhibited significant growth potential that was manifested as 148-fold increase in cell numbers. Flow cytometry and immunocytochemistry demonstrated that CB AC133+ cells' expression of endothelial progenitor markers was not affected by long term in vitro culturing. After culturing under EC differentiation conditions, cells exhibited high expression of mature ECs markers, such as CD31, VEGFR-2 and von Willebrand factor, as well as the morphological changes indicative of differentiation towards mature ECs. In addition, throughout the 30 day culture cells preserved their functional capacity that was demonstrated by high uptake of DiI fluorescently conjugated-acetylated-low density lipoprotein (DiI-Ac-LDL), in vitro and in vivo migration towards chemotactic stimuli and in vitro tube formation.
  
  
  CONCLUSIONS
  These studies demonstrate that primary CB AC133+ culture contained mainly EPCs and that long term in vitro conditions facilitated the maintenance of these cells in the state of commitment towards endothelial lineage.
authors.affiliation: Cellular and Molecular Imaging Laboratory, Department of Radiology, Henry Ford Hospital, Detroit, Michigan, United States of America. bjanic@rad.hfh.edu
authors.forename: Branislava
authors.initials: B
authors.lastname: Janic
authors.forename: Austin M
authors.initials: AM
authors.lastname: Guo
authors.forename: A S M
authors.initials: AS
authors.lastname: Iskander
authors.forename: Nadimpalli Ravi S
authors.initials: NR
authors.lastname: Varma
authors.forename: Alfonso G
authors.initials: AG
authors.lastname: Scicli
authors.forename: Ali S
authors.initials: AS
authors.lastname: Arbab
mesh_terms: D000071916:AC133 Antigen; D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology* / Q000378:metabolism / Q000637:transplantation; D005260:Female; D005312:Fetal Blood / Q000166:cytology*; D005434:Flow Cytometry; D006023:Glycoproteins / Q000032:analysis; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D016130:Immunophenotyping; D007700:Kinetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010455:Peptides / Q000032:analysis; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D013997:Time Factors; D014183:Transplantation, Heterologous; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C000606024:Prom1 protein, mouse; D014841:von Willebrand Factor