The effects of megakaryocytic stimulators on the characterization of murine megakaryocytic colonies in a liquid culture system

Nagasawa, T.; Nakazawa, M.; Abe, T.

Nihon Ketsueki Gakkai Zasshi Journal of Japan Haematological Society 47(7): 1467-1475


ISSN/ISBN: 0001-5806
PMID: 6532051
Accession: 006665276

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The characteristics of in vitro murine megakaryocytic colony induced by pokeweed mitogen-stimulated spleen cell-conditioned medium (PWM-SC-CM) and crude erythropoietin preparation (Epo) were compared in a liquid culture system. Both stimulators could induce 2 different types of megakaryocytic colonies, i.e., heterogeneous colony and homogeneous colony. Both types of colonies retained their shape without dispersing in this liquid culture for 7 days. The heterogeneous colony consisted of 16-64 acetylcholinesterase-positive cells with varying cell size included granulocytic and/or erythrocytic colonies, possibly derived from bipotent or tripotent stem cells. The homogeneous colony was pure megakaryocytic colony consisting of 4-8 acetylcholinesterase-positive cells, possibly derived from CFU-M [Megakozocyte colony forming unit]. The number of heterogeneous colonies increased to a greater extent than homogeneous colonies in the presence of PWM-SC-CM whereas homogeneous colony became predominant in the presence of Epo. The mean ploidies of heterogeneous colonies induced by PWM-SC-CM and Epo were 6.4 .+-. 2.3 N and 6.8 .+-. 3.0 NU on day 5 of culture ,respectively, and remained low during culture. In contrast, the mean ploidies of homogeneous colonies induced by PWM-SC-CM and Epo were 18.3 .+-. 7.2 N and 26.0 .+-. 7.0 NH on day 5 of culture, respectively. In ultrastructural analyses, the megakaryocytes in the heterogeneous colonies induced by PWM-SC-CM and Epo were mostly immature (type I). Type II and III megakaryocytes were predominant in the homogeneous colony induced by Epo. PMW-SC-CM acted preferentially on the early proliferation of murine megakaryocytic progenitor cells and Epo influenced the proliferation and endomitosis of CFU-M.