Validation of a serum-free growth factor-replenished in vitro culture system for hematopoietic progenitor cells in healthy donors and recipients of an allogeneic bone marrow graft.

The in vitro colony formation of hematopoietic progenitor cells of bone marrow samples, taken before and early after allogeneic bone marrow transplantation (BMT), was investigated prospectively. In order to circumvent culture-related and sample-related variations, a serum-free recombinant growth factor-replenished culture system was developed using T cell- and monocyte-depleted bone marrow samples. Samples of healthy bone marrow donors were used to validate the technique. The standardized culturing technique gave reproducible results, with numbers of colonies above those in conventional conditioned-medium technique. Colony formation in vitro of myelomonocytic precursor cells was found decreased in graft recipients, also after addition of growth factors, in comparison with healthy donors. The growth-promoting effect of the combination of IL-3 + GM-CSF was superior to that of either growth factor alone or conditioned medium. No effect was observed of T lymphocytes and monocytes on in vitro colony formation after bone marrow transplantation, probably as a result of functional impairment of these cells at that period after transplantation.