The role of platelet-derived growth factor on human pluripotent progenitor (CFU-GEMM) growth in vitro

The effect of serum on the proliferation of human bone marrow pluripotent progenitor cells (CFU-GEMM), was compared to that of fresh frozen plasma (FFP). Serum significantly increased the number of mixed erythroid-granulocytic-megakaryocytic colonies (CFU-GEMM) and erythrocytic bursts (BFU-E) in this assay system (p less than 0.01 and 0.02, respectively). Two possible explanations for this finding were considered: first the presence of citrate-phosphate-dextrose (CPD) in plasma but not in serum, and second the presence of platelet-derived growth factor (PDGF) in serum but not in plasma. CPD was indeed found to have an inhibitory effect on growth of colonies of all types when added to serum-stimulated cultures. Nevertheless, when heparinized plasma was compared to serum from the same donors, growth of CFU-GEMM and BFU-E was higher in the serum-stimulated cultures (p less than 0.001 and p less than 0.05, respectively). PDGF at concentrations of 120-240 pM was found to enhance the formation of CFU-GEMM and BFU-E by three- and four-fold respectively when added to cultures containing FFP but not when added to cultures containing serum derived from whole blood (WBS). Purified PDGF added at the same concentrations, to cultures containing platelet-poor derived serum (PDS), promoted similar increases in growth of CFU-GEMM and BFU-E but not of granulocytic-macrophage or megakaryocytic colonies. Whether PDGF has a direct action on CFU-GEMM or its growth promoting activity is via an interacting cell population is currently being studied.