Dragon's blood extracts reduce radiation-induced peripheral blood injury and protects human megakaryocyte cells from GM-CSF withdraw-induced apoptosis

Purpose: Dragon's blood (DB), a Chinese traditional herb, was shown to have certain protective effects on radiation-induced bone marrow injury due to the presence of several phenolic compounds. The 50% ethanol extracts (DBE) were separated from DB by the methods of alcohol extracting-water precipitating. The protective effects of DBE on hematopoiesis were studied, particularly on megakaryocytes. Materials and methods: In this study, we investigated the in vivo radioprotective effects of DBE on hematopoiesis and pathological changes using an irradiated-mouse model. Moreover, the protective effects and potential molecular mechanisms of DBE on megakaryocytopoiesis in vitro were explored in GM-CSF depletion-induced Mo7e cell model. Results: DBE significantly promoted the recovery of peripheral blood cells in irradiated mice. Histology bone marrow confirmed the protective effect of DBE, as shown by an increased number of hematopoietic cells and a reduction of apoptosis. In a megakaryocytic apoptotic model, DBE (50 μg/mL) markedly alleviated GM-CSF withdrawal-induced apoptosis and cell-cycle arrest of Mo7e cells. DBE (50 μg/mL) also significantly decreased the ratio of Bax to Bcl-2 expression, inhibited the active caspase-3 expression. In addition, DBE could induce ERK1/2 phosphorylation in GM-CSF-depleted Mo7e cell, but not Akt. Conclusions: Our data demonstrated that DBE could effectively accelerate the recovery of peripheral blood cells, especially platelet. DBE attenuated cell apoptosis and cell cycle arrest through the decrease of Bax/Bcl-2 ratio and the reduction of active caspase-3 expression. The effect of DBE on Mo7e cells survival and proliferation is likely associated with the activation of ERK, but not Akt.