Pig bone marrow and peripheral blood erythroid progenitor cells in S phaseof the cell cycle

The proliferative rate of hemopoietic progenitor cells, ie. the percentage of cells in the synthetic (S) phase of the cell cycle is a very sensitive p arameter for detecting the steady-state misbalance arising in response to s timulatory or inhibitory molecules, or in postmyeloablative repopulation of hemopoiesis. This parameter is also predictive for the sensitivity of thes e cells to irradiation injury and specific cytotoxic drugs. In spite of the fact that miniature inbred and domestic pig breeds have been used as large animal models in hemopoietic research and in experimental bone marrow tran splantation, data concerning the proliferative rate of porcine progenitor c ells are still lacking. The aim of this study was to examine the steady-sta te proliferative rate of bone marrow and peripheral blood erythroid progeni tor cells of adult pigs. The percentage of cells in S phase of the cell cyc le of both immature, BFU-E (Burst Forming Unit-Erythroid) and mature, CFU-E (Colony Forming Unit-Erythroid) erythroid progenitor cells was determined by the suicide technique based on the proportion of these cells killed afte r in vitro treatment of the cells with cytosine arabinoside (Ara-G). The re sults revealed different relative numbers of immature and mature erythroid progenitor cells in S phase of the cell cycle in the bone marrow, namely, 3 3.3% for BFU-E and 55.1% for CFU-E. in peripheral blood the proliferative r ate of BFU-E progenitors was 26.3%. The data obtained show that the prolife rative rate of porcine erythroid progenitor cells is similar to the values determined for other mammalian species.