基于纳米结构的物理性niche调控MSC软骨向分化及促进大块骨软骨缺损再生研究

The clinical challenges relating to large osteochondral lesion repair are cartilage collapse and inferior mechanical properties in the subchondral bone layer, usually due to the failure of cartilage-bone healing. The basic biology of osteochondral healing remains incompletely understood. So it's necessary to design effective tissue-engineered scaffold for osteochondral regeneration. Recently some studies showed that matrix micro-environment could directly affect stem cell differentiation by integrin-mediated mechanotransduction pathway. So it's hypothesized that scaffold niche based on nano-structure could regulate the MSCs chondrogenesis by providing integrin-mediated molecular signal pathways and improve healing response in cartilage defect. In the current study main factors of matrix micro-environment affect MSCs differentiation will be produced based on 3-D nanofibrous structure. Then pathway how molecule signals affect MSC differentiation will be investigated. Finally the osteochondral scaffold on where MSCs are planted will be used to repair large osteochondral defect in vivo with the aim of developing an efficient tissue-engineered scaffold. This study is supposed to produce original experimental data and provide a new way to regulate MSC differentiation. With stem cell differentiation and tissue engineering technology, a novel 3-D tissue-engineered osteochondral graft could be manufactrured. This new strategy may realize the clinical translation of tissue engineered graft for regenerative medicine in future.

临床上，软骨塌陷和软骨下骨支撑不足是大块骨软骨缺损修复术后的常见问题。目前，有关骨软骨愈合机制尚不明确，因此临床上尚缺乏理想的生物支架用于组织工程骨软骨的构建。最新研究表明基质微环境可以通过整合素介导的力学转导通路影响干细胞分化。本研究假说：基于纳米结构的物理性niche可以定向调控MSCs分化，并通过微环境中整合素介导的力学转导信号通路影响软骨愈合。该研究拟利用前期成功建立的纳米纤维三维支架结构，模拟并控制基质微环境的不同变量，研究影响MSC软骨分化的主要拓扑结构，并明确调控机理，最后通过在体内原位骨软骨修复实验，评估组织工程化骨软骨支架的可行性和功效性。该研究将为调控MSCs向软骨分化提供全新的思路，并为利用干细胞和生物材料修复大块骨软骨缺损提供新的理论依据和新技术手段。

软骨组织是不可再生的，因此临床上软骨损伤后将导致组织的一系列退化性病变，如骨关节炎。本研究通过体外实验得到了一群软骨源性的干/祖细胞，既CDPCs。并进一步鉴定了CDPCs的特性，结果发现其能稳定表达成熟软骨细胞的标志COL2，以及间充质干细胞的标志CD146。本研究通过体内和体外实验发现，CDPCs与骨髓间充质干细胞表型相同，但有更强的软骨修复能力。在临床病人中，CDSCs能够修复大块膝关节软骨损伤。这些研究结果提示，软骨细胞能够转化为CDPCs，并建立了促进软骨细胞转化为CDPCs的培养系统，从而为临床治疗软骨损伤提供了可靠的细胞来源及治疗方法。同时，本研究研发了新型骨软骨组织工程支架，通过体内外实验发现，该支架可以有效修复大块骨软骨损伤，并通过结合PTHrP等生长因子，可进一步促进骨软骨修复，以期今后应用于临床，造福众多骨软骨组织缺损病人。