HETEROGENEITY IN THE IN-VITRO SURVIVAL AND PROLIFERATION OF HUMAN SEMINOMA CELLS

The in vitro culture conditions allowing survival and initial prolifer ation of murine primordial germ cells from 10.5 days post coitum embry os, which include the use of a murine embryonal fibroblast (STO) feede r, were applied to 21 human seminomas, composed of tumour cells which are considered as the malignant counterparts of human primordial germ cells. Cells from 18 seminomas attached poorly to STO, and only a few survived through day 10. In contrast, three seminomas showed a higher degree of attachment. Two of them showed initial proliferation and enh anced survival: 30 days for tumour SE1 and 25 days for tumour SE3. Tum our SEI was more extensively studied, using the culture conditions all owing the derivation of pluripotent embryonic stem cells from 8.5 days post coitum murine primordial germ cells, which include the use of ST O feeder, stem cell factor, leukaemia inhibitory factor and basic fibr oblast growth factor. The presence of stem cell factor was necessary a nd sufficient for colonies of tumour cells to form during the first 3 days of culture. While the cell number decreased after day 3 in medium without fetal calf serum, it increased until day 9 in medium containi ng fetal calf serum. No reprogramming of SE1 cells to pluripotent stem cells was observed. Our data indicate that seminomas form a tumour po pulation with a heterogeneous in vitro behaviour not equivalent to tha t of 8.5-10.5 days post coitum murine primordial germ cells.