In Vivo Effects of Urinary Extracts of Patients with Aplastic Anemia on Rat Platelet Production and Megakaryocyte Progenitors in Murine Spleen and Bone Marrow
We examined the quantitative changes in the circulating platelets of rats and in the megakaryoctye progenitor content of mouse spleens and bone marrows after administration of urinary extracts from patients with aplastic anemia (AA). Single intraperitoneal injections of 140 μg and 30 μg of protein (65–90% ethanol precipitate of crude urinary preparation) were administered to Sprague-Dawley rats and BDF1 mice, respectively. Circulating platelet counts in rats increased significantly 24 h after the injection. Total megakaryocyte colony-forming cells (CFU-Meg) in mouse spleens increased 24 h post-injection, peaked at 48 h, and returned to normal levels 96 h after the injection. Changes in the number of megakaryocyte colonies showed that colonies composed of five or more megakaryocytes increased significantly 6 h after the single injection; however, colonies with two megakaryocytes began to increase significantly 24 h post-injection, peaked by 48 h, and returned to normal levels after 96 h.
A significant increase in the number of solitary megakaryocytes was observed 48 h post-injection, with the maximum number occuring after 72 h, remaining at this relatively high level for up to 96 h after the injection. In contrast to the spleen, no statistically significant changes were observed in either total CFU-Meg or solitary megakaryocytes in the bone marrow during the 96 h of observation after the AA urinary extract injection. Our results show that the urinary extract of aplastic anemia patients contains a factor that directly stimulates splenic megakaryocyte progenitors in vivo as well as the release of platelets from mature megakaryocytes and/or platelet pools.
Key wordsAplastic anemia urinary extract platelet production megakaryocyte progenitors (CFU-Meg)
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