仿生基质细胞龛联合Notch信号通路活化扩增脐血造血干细胞的实验研究

Hematopoietic stem cells expansion in vitro still have a lots of debates and be faced with great challenges. In physiological situation, umbilical cord blood (UCB) stem cells reside in a three dimensional environment that consist of stromal cells (endothelial cells primarily). In this study, we plan to construct the bionic endothelial progenitor cells (EPCs) niche and the bionic umbilical cord mesenchymal stem cells (UCMSCs) niche with tissue engineering technique. We employ the 3D polymer material InsertTM-PS as scaffold, composite with the EPCs derived from UCB mononuclear cells (MNCs) and the UCMSCs separated from Wharton's jelly as co-culture stromal cells. The CD34+ cells from UCB are implanted to the two stromal cells niches and are cultured without additional cytokine supplement. We will observe the role of UCB stem cells expansion and maintenance in the bionic stromal cells niches in vitro. Notch signals pathway play an important role between cell to cell interactions. Hematopoietic stem/progenitor cells express Notch receptors and stromal cells express their ligands. Notch signals promote the self-renewal and suppress the differentiation of hematopoietic stem/progenitor cells. With biological engineering technology, we plan to clone and purify the extracellular domain of Notch1 ligand Delta-1 (hDll-1ext) with biological activity, and combine with the two stromal cells bionic niches to expanse UCB stem/progenitor cells in vitro. and explore to the mechanism of regulating UCB stem cells in self-renewal, maintenance, and proliferation. Finally, integration of the 3D stromal cells co-culture, cytokine support, and signals pathways knowledge and methods migh to raise a novel strategy for expansion of hematopoietic stem/progenitor cells in vitro.

脐血干细胞体内生理环境是基质细胞为主的三维结构。本课题采用组织工程技术用脐血干细胞来源的内皮祖细胞和脐带Wharton's胶来源的间充质干细胞为基质细胞，复合3D InsertTM-PS高分子材料支架，构建仿生内皮祖细胞龛和脐带间充质细胞龛，将脐血CD34+细胞植入，无外源细胞因子添加，研究对脐血干/祖细胞的扩增和支持作用。Notch信号通路在细胞间相互作用中具有重要作用，造血干/祖细胞与基质细胞表面分别表达Notch受体和配体，激活Notch通路能够促进造血干/祖细胞的自我更新，并抑制其分化。本研究采用生物工程技术制备Notch1 配体Delta-1胞外区可溶性活性产物hDll-1ext，联合仿生基质细胞龛扩增脐血造血干/祖细胞，从Notch信号通路探讨对脐血干/祖细胞自我更新及分化的调控机制。将仿生造血龛培养同信号通路调节剂，细胞因子等方法整合，探索体外扩增造血干/祖细胞的新策略。