Pig bone marrow and peripheral blood erythroid progenitor cells in S phase of 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 parameter for detecting the steady-state misbalance arising in response to stimulatory or inhibitory molecules, or in postmyeloablative repopulation of hemopoiesis. This parameter is also predictive for the sensitivity of these 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 transplantation, data concerning the proliferative rate of porcine progenitor cells are still lacking. The aim of this study was to examine the steady-state proliferative rate of bone marrow and peripheral blood erythroid progenitor cells of adult pigs. The percentage of cells in S phase of the cell cycle 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 after in vitro treatment of the cells with cytosine arabinoside (Ara-G). The results revealed different relative numbers of immature and mature erythroid progenitor cells in S phase of the cell cycle in the bone marrow, namely, 33.3% for BFU-E and 55.1% for CFU-E. in peripheral blood the proliferative rate of BFU-E progenitors was 26.3%. The data obtained show that the proliferative rate of porcine erythroid progenitor cells is similar to the values determined for other mammalian species.