A COMBINATION OF BUFFALO RAT-LIVER CELL-CONDITIONED MEDIUM, FORSKOLINAND MEMBRANE-BOUND STEM-CELL FACTOR STIMULATES RAPID PROLIFERATION OFMOUSE PRIMORDIAL GERM-CELLS IN-VITRO SIMILAR TO THAT IN-VIVO

Recent studies have shown that stem cell factor (SCF), leukemia inhibi tory factor (LIF), basic fibroblast growth factor (bFGF) and the enhan cement of cAMP levels increase proliferation and survival of mouse pri mordial germ cells (PGC) in vitro. Even after the addition of these fa ctors, however, it is still not possible to obtain proliferation of PG C at a rapid rate similar to that in vivo, suggesting the presence of other growth factor(s) in vivo. We previously reported that tumor necr osis factor-alpha stimulates proliferation of PGC at earlier migration stages. We now show that the use of SI/SI4-m220 feeder cells and the addition of a medium conditioned with Buffalo rat liver cells and fors kolin to the culture medium stimulate PGC obtained from 8.5 days post coitum embryos to proliferate in culture at a rate comparable to that in vivo. Under such conditions, proliferation of PGC continued several days past the timing of growth arrest in vivo; however, it did stop a fterwards. Such proliferating PGC continue to express c-kit and Oct-3 proteins. The characteristics of the culture medium and the requiremen t of feeder cells were different from those for embryonic stem (ES) ce lls, suggesting that these rapidly proliferated PGC are not transforme d into ES-like EG cells.