Long-term repopulation of irradiated mice with limiting numbers of purified hematopoietic stem cells : in vivo expansion of stem cell phenotype but not function

摘要: Hematopoietic stem cells were isolated from normal adult mouse bone marrow based on surface antigen expression (Thy-1.1(low)Lin(neg)Ly- 6A/E+) and further selected for low retention of rhodamine 123. This population (Rh-123low) could mediate radioprotection long- term (greater than 12 months) repopulation after transplantation as few 25 cells. Transfer five genetically marked Rh-123low in the presence 10(5) resulted reconstitution peripheral blood by greater 10% donor 64% (30 47) recipient mice. Of 46 animals surviving 24 weeks, 10 had over 50% donor-derived blood. Two general patterns long-term observed: one which many observed 5 to 6 weeks another rare initially but expanded with time. result suggests that two classes repopulating hematopoietic exist, differing their ability function early course transplantation. Alternatively, distinct anatomic sites engraftment may dictate these outcomes a single type cell. As an approach measure extent self-renewal injected cells, recipients or 200 killed 8 13 months transplants, Thy- 1.1(low)Lin(neg)Ly-6A/E+ progeny original second transplant. While numerical expansion expressing cell phenotype was observed, along activity colony-forming unit-spleen assay, vastly inferior assays when compared freshly animals. demonstrates experiments, is not appropriate indicator function.