Effect of murine kidney extracts on the proliferation of hematopoietic progenitor cells in human umbilical cord blood

We examined the effect of murine kidney extract (MKE) on the clonal growth of highly purified CD34(+) hematopoietic progenitor cells from human umbili cal ford blood. MKE did not affect the total number of colonies of erythroi d burst-forming units (BFU-E). granulocyte-macrophage colony-forming units (CFU-GM) or granulocyte-erythroid-macrophage-megakaryocyte colony-forming u nits (CFU-Mix/CFU-GEMM) in a methyl-cellulose culture with exogenous recomb inant human granulocyte colany-stimulating factor; granulocyte-macrophage c olony-stimulating factor, interleukin-3, stem cell factor and erythropoieti n. MKE significantly increased the proportion of BFU-E- or CFU-Mix-derived colonies, and suppressed the formation CFU-GM-derived felonies depending on the MKE dose. However, because of an increase in small megakaryocyte colon ies derived from mature CFU-Meg MKE increased bl approximately 40% the grow th of megakaryocyte colony-forming units (CFU-Meg) in plasma clot culture s timulated by recombinant human thrombopoietin. Also MKE promoted an increas e in hyperploid megakaryocytes, suggesting that the active factor(s) in MKE acts on the mature CFU-Meg and promotes the maturation of megakaryocytes, Gel-filtration high performance liquid chromatography. of MKE showed that t he promoting factor(s) in MKE was approximately 45 kDa, These results indic ate that the factor(s) detected in MKE influence human hematopoiesis in vit ro, especially thrombopoiesis.