Phenotypic Definition of the Progenitor Cells with Erythroid Differentiation Potential Present in Human Adult Blood

摘要

In Human Erythroid Massive Amplification (HEMA) cultures, AB mononuclear cells (MNC) generate 1-log more erythroid cells (EBs) than the correspondingCD34poscells, suggesting that MNC may also containCD34negHPC. To clarify the phenotype of AB HPC which generate EBs in these cultures, flow cytometric profiling for CD34/CD36 expression, followed by isolation and functional characterization (colony-forming-ability in semisolid-media and fold-increase in HEMA) were performed. Four populations with erythroid differentiation potential were identified:CD34posCD36neg(0.1%);CD34posCD36pos(barely detectable-0.1%);CD34negCD36low(2%) andCD34negCD36neg(75%). In semisolid-media,CD34posCD36negcells generated BFU-E and CFU-GM (in a 1 : 1 ratio),CD34negCD36negcells mostly BFU-E (87%) andCD34posCD36posandCD34negCD36lowcells were not tested due to low numbers. Under HEMA conditions,CD34posCD36neg,CD34posCD36pos,CD34negCD36lowandCD34negCD36negcells generated EBs with fold-increases of≈9,000, 100, 60 and 1, respectively, and maturation times (day with >10%CD36highCD235ahighcells) of 10–7 days. Pyrenocytes were generated only byCD34neg/CD36negcells by day 15. These results confirm that the majority of HPC in AB express CD34 but identify additionalCD34negpopulations with erythroid differentiation potential which, based on differences in fold-increase and maturation times, may represent a hierarchy of HPC present in AB.