The effects of plasma gelsolin on human erythroblast maturation for erythrocyte production.

Gelsolin is an actin binding protein present in blood plasma and in cytoplasm of cells including macrophages. Gelsolin has important functions in cell cycle regulation, apoptotic regulation, and morphogenesis. Even though bone marrow macrophages and serum factors are critical for regulating erythropoiesis, the role of gelsolin on human erythroblasts has not been studied. Here, we investigated the effects of human recombinant plasma gelsolin (pGSN) on human immature erythroblasts. CD34+ cells isolated from cord blood were differentiated into erythroid cells in serum-free medium. When pGSN was applied to the culture medium, it accelerated basophilic and polychromatic erythroblast maturation and increased the enucleation rate with highly expressed erythropoiesis-related mRNAs. Also, pGSN was effective in reducing dysplastic changes caused by vincristine, suggesting its role in cell cycle progression at G2/M checkpoints. Also, pGSN activated caspase-3 during maturation stages in which caspase-3 functions as a non-apoptotic maturational signal or a pro-apoptotic signal depending on maturation stages. Our results suggest that pGSN has a pivotal role in maturation of erythroblasts and this factor might be one of the way how bone marrow macrophages and previously unknown serum factors work to control erythropoiesis. pGSN might be used as additive for in vitro production of erythrocytes.