Analysis of hemopoietic stem cell proliferation and differentiation using hg-csf receptor transgenic mice

It is hypothesized that self-renewal and differentiation of stem cells and progenitors appear to be stochastic processes, and that survival and differentiation of the cells may be regulated by cytokines. Recent studies of our group using hematopoeitic cells expressing exogenously introduced receptors for human granulocyte/macrophage colony stimulating factor (hGM-CSFR), revealed that GM-CSF is rather a proliferation-promoting factor for various cells than a differentiationinducing factor of specific lineages. To examine this observation is ubiquitously applicable to other cytokines, we took similar strategy using human granulocyte colony stimulating factor receptor (hG-CSFR) transgenic (Tg)-mice. Since G-CSF is believed to be a differential inducing factor to G-!ineage, it might be very interests and important to examine how G-CSF acts in hematopoiesis of hG-CSFR. hG-CSFR Tg-mice were generated by a standard oocyte injection method using the C3H/HeN strain. The hG-CSFR construct was designed to achieve ubiquitous expression of the transgene RNA products in Tg-mice. We analyzed the hematological changes of peripheral blood, bone marrow (BM), .spleen and peritonea! cells of the Tg-mice comparing with littermates. There was no significant difference in body weights, organ weights and hematological findings between Tg-mice and littermates. By dona! culture of BM and spleen cells of Tg-mice but not of littermates, hCi-CSF showed an effect on promoting megakaryocytic (MK) colony formation and an inhibitory effect on erythroid colony formation in both serum-containing and serum-free culture. To exclude the influence of accessory cells, we used Lin' BM cells, and got the same results. With bone marrow cells of 5-FU-treated mice, hG-CSF also showed a significant stimulatory effect on primitive hematopoeisis in synergistic action with SCF or IL-3. hG-CSF manifested a strong restrained effect on colony formation by mature mast cells sorted from peritoneal cells in serum-free culture. Our data suggest that differing from hGM-CSF, hG-CSF plays dualistic roles in hematopoiesis.