骨形态发生蛋白诱导髓外造血的实验研究

Empirical study on inducing extramedullary hematopoiesis by bone morphogenetic protein

目的:探讨骨形态发生蛋白(BMP)诱导髓外造血以拯救骨髓造血衰竭的作用。方法:采用60Co-γ+氯霉素(CH)+环磷酰胺(CY)的方法诱导小鼠致死性再生障碍性贫血模型,实验组于诱导再障前6d肌肉内植入重组人-BMP-4(rh-BMP-4),对照组小鼠肌肉内植入琼脂。观察血象、病理形态等变化以及两组再障小鼠的死亡率。同时,给正常小鼠大腿肌肉内植入rh-BMP-4,动态观察植入后局部的形态变化、形成骨及骨髓的形态特点,脾集落形成单位(CFU-S)以及基质细胞干细胞生长因子(SCF)的表达。结果:正常小鼠在BMP肌肉内植入1周内,在BMP周围有大量间质细胞增殖,2周后才出现软骨化骨和骨小结形成,其骨髓基质细胞的SCF表达明显高于自体骨髓;BMP植入组的再障小鼠,不仅血象与对照组相比有明显改善,而且死亡率也明显下降,有46.7%存活超过3个月,其血象完全恢复正常,骨髓和脾脏的组织形态学改变也恢复正常。对照小鼠除1只存活超过3个月外(占6.7%),其余均死于急性再生障碍性贫血。结论:肌肉内植入BMP-4可诱导髓外造血,其机制可能与BMP-4诱导成年自体肌肉内存在的干细胞向造血分化有关,这一结果将为干细胞治疗提供了一条新的思路。

Objective ： To explore the effect of bone morphogenetic protein （BMP） to induce extramedullary hematopoiesis for rescuing bone marrow failure. Methods： The study was performed on lethal rat acute aplastic anemia model induced by combined 60^Co-γ chloramphenicol（CH） and cyclophosphamide （CY）. The rh-BMP-4 was implanted into the thigh muscle of the rats at 6 days before aplastic anemia was induced. In the control group the rats were implanted with agar into the thigh muscle. The blood picture, pathologic changes and the mortality in two groups were observed. At the same time, rh-BMP-4 were implanted into the thigh muscle of normal BALB/C mice for dynamic control observation of the implantation local morphological changes, colony forming units -spleen （CFU-S） and stem cell growth factor growth factor （SCF） expression of the stroma cells of ectopic ossicle induced by BMP. Results： On ＋ 7 day after BMP implantation in the mice the mesenchymal cells around BMP in muscle proliferated, and appeared in bone marrow to form os cartilaginea and an ectopic ossicles at two weeks. The SCF expression of stroma cells in ectopic ossicles was higher than that of self - bone marrow. 46.7% of BMP - treated aplastic rats were survived over 3 months and its hematopoiesis was completely reconstituted and the histo - morphological picture of the spleen and bone marrow were recovered to normal. But in the control group only one of 15 rats was survived, the reminder died of hematopoietic failure. Conclusion： BMP-implantation into the skeletal muscle could induce extramedullary hematopoiesis for rescuing bone marrow failure. The mechanism might be related to the BMP activated auto-mesenchymal cells of skeletal muscle to direct hematopietic cell differentiation. It might create a new thinking for stem cell therapy.