Sachiko Kajigaya

Establishment of megakaryoblastic cell lines by coinfection of Abelson murine leukemia virus and recombinant SV40-retrovirus.

Murine embryonic cells including yolk sac prepared from 8‐day embryos were co‐infected with Abelson murine leukemia virus (A‐MuLV) and/or a recombinant retrovirus containing large T and small t antigens, and early region of simian virus 40 (M‐SV40). By coinfection with A‐MuLV and M‐SV40, megakaryoblastic cells were obtained in addition to mast cells and fibroblastic cells. However, following infection with A‐MuLV or M‐SV40 alone, no megakaryoblastic cells were detected, although mast cells and/or fibroblastic cells developed. The same results were obtained in several experiments. By single‐cell transfer, 6 acetyl‐cholinesterase (AchE)‐positive clonal cell lines were established. Characteristics of megakaryocytes, such as AchE, glycoproteins lIb and IlIa, and platelet peroxidase were detected in two representative cells (C1 and C8). More significant changes expressing differentiation were observed following treatment with phorbol myristate acetate or pokeweed mitogen‐stimulated murine spleen cell conditioned medium, although release of platelets was not observed. This is the first report showing development of megakaryocytic cells as the result of coinfection with retroviruses.

Stimulation of erythropoiesis in teratocarcinoma cells by erythropoietin and “Friend inducers”

Abstract Murine teratocarcinoma cells (PCC3/A1) formed erythroid cells in the form of blood islands when they were grown in organ culture. Addition of dimethyl sulfoxide (DMSO), N′N-dimethylacetamide and erythropoietin enhanced the formation of blood islands. An additive stimulatory effect was observed when expiants were incubated with DMSO and erythropoietin. In all of these cultures, the formed erythroblasts showed the characteristics of primitive erythroid cells, regardless of the nature of treatment. Small, enucleated red cells were occasionally observed. These results are compared with the characteristics of erythropoiesis in normal adults, embryos and in murine erythroleukemia.