成人外周血细胞重编程为间充质干细胞的机理研究

Mesenchymal stem cells (MSCs) are mesoderm stem cells with multi-lineage differentiation potential. MSCs have been used in clinical trials to repair or regenerate damaged or diseased tissues and organs.However, the therapeutic efficacy is unsatisfactory in many applications due to insufficient cell number and limited regenerative potential of MSCs derived from elder patients. Although generation of iPSCs followed by direct differentiation into MSCs is able to provide large quantities of rejuvenated stem cells for therapy, the tumorigenecity of residual undifferentiated iPSCs remains a safety concern of iPSC-based therapy. Recently, we reported that OCT4 synergizes with WNT signaling to reprogram human hematopoietic cells into induced MSCs or iMSCs efficiently and rapidly. This exciting finding provides a novel alternative strategy for generating autologous MSCs. We will use reprogramming factors-expressing episomal vector and small molecule compounds to reprogram adult peripherial blood mononuclear cells into iMSCs and identify novel factors that can rejuvenate iMSCs using systems biology approaches.We will further identify the molecular mechanisms of OCT4 and WNT signaling-mediated hematopoietic cell reprogramming and rejuvenation.

间充质干细胞(mesenchymal stem cells,MSC)具有多向分化潜能，在临床试验中已开始用于修复受伤或病变的组织器官。但从成人体内获得的MSC数量有限，再生潜力低。体细胞重编程为诱导多能干细胞（iPS细胞）再定向分化可提供大量MSC，但残留iPS细胞的致瘤性和长期体外培养的高成本影响了该治疗策略的应用前景。我们发现，OCT4与激活WNT的小分子化合物协同作用可高效快速地转分化血细胞为诱导间充质干细胞（iMSC），iMSC无致瘤性且比成人MSC具有更强的增殖能力。据此我们提出一个新的自体MSC治疗策略：重编程成人外周血细胞为iMSC，并使MSC“返老还童”，重新获得类似胚胎源细胞的再生能力。为实现这一目标，我们将建立高效非病毒重编程体系，研究血细胞重编程为iMSC以及iMSC维持干性的分子机理。

该项目基本按照研究计划执行。间充质干细胞(mesenchymal stem cells,MSC)具有多向分化潜能，在临床试验中已开始用于修复受伤或病变的组织器官。但从成人体内获得的MSC数量有限，再生潜力低。我们课题组成功实现体细胞重编程为诱导多能干细胞（iPS细胞），进而进一步优化了体细胞直接重编程为间充质干细胞系统。为了促进诱导多能干细胞和间充质干细胞的应用，我们系统优化了CRISPR-Cas9基因编辑工具在诱导多能干细胞和间充质干细胞的基因编辑效率。取得了一系列原创性和突破性的研究成果。