Cord blood plasma-mediated ex vivo expansion of hematopoietic progenitor cells.

Cord blood (CB) plasma has previously been found to augment the replating capacity of CB-derived hematopoietic progenitors. In the present study, we observed a 2.8 +/- 0.3 and a 1.8 +/- 0.2-fold expansion of CFU-GM in cultures of CB cells without growth factors but supplemented by CB plasma or maternal blood (MB) plasma, respectively. In the absence of growth factors, CFU-GM expansion did not occur in CB cell cultures supplemented with fetal calf serum (FCS), peripheral blood (PB) plasma, PB plasma plus concentrations of IL-6 similar to those previously reported in CB plasma and in bone marrow (BM) cell cultures supplemented with FCS, CB, MB or PB plasma. In the presence of stem cell factor (SCF), IL-3 and IL-11, an expansion of CFU-GM was observed in CB and BM cell cultures supplemented by either CB, MB or PB plasma or FCS. Nevertheless, progenitor expansion was significantly superior in CB cell cultures supplemented by CB plasma (8.7 +/- 0.7, 2.4 +/- 0.3 and 2.6 +/- 0.3-fold expansions for CFU-GM, BFU-E and CFU-Mix, respectively). In conclusion, an unknown factor(s) present in CB plasma, probably capable of crossing the placenta, has an effect alone and in the presence of growth factors in supporting ex vivo expansion of CB progenitors.