Absence of a relationship between immunophenotypic and colony enumeration analysis of endothelial progenitor cells in clinical haematopoietic cell sources.
BACKGROUND
The discovery of adult endothelial progenitor cells (EPC) offers potential for vascular regenerative therapies. The expression of CD34 and VEGFR2 by EPC indicates a close relationship with haematopoietic progenitor cells (HPC), and HPC-rich sources have been used to treat cardiac and limb ischaemias with apparent clinical benefit. However, the laboratory characterisation of the vasculogenic capability of potential or actual therapeutic cell autograft sources is uncertain since the description of EPC remains elusive. Various definitions of EPC based on phenotype and more recently on colony formation (CFU-EPC) have been proposed.


METHODS
We determined EPC as defined by proposed phenotype definitions (flow cytometry) and by CFU-EPC in HPC-rich sources: bone marrow (BM); cord blood (CB); and G-CSF-mobilised peripheral blood (mPB), and in HPC-poor normal peripheral blood (nPB).


RESULTS
As expected, the highest numbers of cells expressing the HPC markers CD34 or CD133 were found in mPB and least in nPB. The proportions of CD34+ cells co-expressing CD133 is of the order mPB>CB>BM approximately nPB. CD34+ cells co-expressing VEGFR2 were also most frequent in mPB. In contrast, CFU-EPC were virtually absent in mPB and were most readily detected in nPB, the source lowest in HPC.


CONCLUSIONS
HPC sources differ in their content of putative EPC. Normal peripheral blood, poor in HPC and in HPC-related phenotypically defined EPC, is the richest source of CFU-EPC, suggesting no direct relationship between the proposed EPC immunophenotypes and CFU-EPC potential. It is not apparent whether either of these EPC measurements, or any, is an appropriate indicator of the therapeutic vasculogenic potential of autologous HSC sources.
Tura
Olga
O
SNBTS Adult Cell Therapy Group, Scottish Centre for Regenerative Medicine, University of Edinburgh School of Clinical Sciences, The Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK. Olga.Tura@ed.ac.uk
Barclay
G Robin
GR
Roddie
Huw
H
Davies
John
J
Turner
Marc L
ML
D000071916:AC133 Antigen; D015703:Antigens, CD / Q000378:metabolism; D018952:Antigens, CD34 / Q000378:metabolism; D002452:Cell Count; D003114:Colony-Forming Units Assay; D042783:Endothelial Cells / Q000166:cytology* / Q000276:immunology*; D006023:Glycoproteins / Q000378:metabolism; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology*; D006801:Humans; D016130:Immunophenotyping; D010455:Peptides / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
D000071916:AC133 Antigen; D015703:Antigens, CD; D018952:Antigens, CD34; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; D040301:Vascular Endothelial Growth Factor Receptor-2