THE EFFECT OF A HEMATOPOIETIC-PROMOTING FACTOR (HPF) EXTRACTED FROM PORCINE KIDNEY ON THE PROLIFERATION OF HUMAN HEMATOPOIETIC PROGENITOR CELLS

Hematopoietic-promoting factor (HPF), which was found in porcine kidne y, has been demonstrated to act synergistically with colony-stimulatin g factor and erythropoietin on murine myeloid colony formation. We inv estigated the effect of HPF on the proliferation of human hematopoieti c progenitor cells prepared from cord blood cells (CB) and peripheral blood cells (PB). HPF enhanced granulocyte colony-stimulating factor p lus interleukin-3 and erythropoietin-induced colony formation, where t he number of colonies were increased by 7.9-fold in CB and by 1.8-fold in PB, respectively. When we compared the effect of HPF with stem cel l factor (SCF) on the colony formation derived from PB in serum-free c ultures, HPF enhanced the number of erythroid burst-forming units (BFU -E) to the same extent as SCF. But the effect of HPF on promoting the growth of granulocyte-macrophage colony-forming units (CFU-GM) was les s than SCF. When the enriched CD34(+) cells from CB and PB were incuba ted in liquid culture with HPF and IL-3 for 7 days, CFU-GM was increas ed by 48-fold in CB, and by 25-fold in PB, respectively. The data demo nstrate that HPF can potentiate expansion of hematopoietic stem cells to the same extent as SCF, and that the effects of HPF on hematopoieti c stem cells differ from that of SCF.