髓核细胞源性活性微载体在ADSCs修复退变椎间盘中的应用和相关机制研究

Bio-scaffold is one of the elements in intervertebral disc tissue engineering. However, the existing bio-scaffold lacking high-efficiency in inducing stem cells differentiating into nucleus pulposus cells (NPCs), and it is difficult to achieve an ideal result in degeneration disc repairation after carrying stem cells. The secretory matrix of NPCs can promote the differentiation of stem cells into a nucleus pulposus phenotype through the combination with the integrins on stem cell surface, and Kindlin-2 is a key regulator in the downstream of integrin signaling pathway. Our previous study found that the secretory matrix of the NPCs can increase the expression of Kindlin-2 in inducing adipose-derived stem cells (ADSCs) differentiating into a nucleus pulposus phenotype, which confirmed Kindlin-2 plays an important role in the differentiation of stem cells into NPCs, in addition, we built a novel NPCs-derived matrix microspheres with good physical, chemical and biological characteristics utilized a new biological method depend on the matrix synthesis and secretion of NPCs. The aim of this research is to study the controllable construction method of the matrix microspheres, and investigate the essential molecular mechanism of Kindlin-2 regulate the TGF-β and Shh pathway in the process of ADSCs differentiate into NPCs with the stimulation of NPCs-derived matrix, and further fabricate a NPCs-derived efficient microcarrier with excellent loading and induction capacity, in addition, evaluate the repairing effect of the ADSCs-microcarrier system in intervertebral disc degeneration.

生物支架是椎间盘组织工程的要素之一，但现有的生物支架无法高效诱导干细胞成髓核定向分化，其搭载干细胞难以达到理想的退变椎间盘修复效果。髓核细胞自分泌基质能通过与干细胞表面整合素受体结合，促进干细胞成髓核细胞定向分化；而Kindlin-2是整合素下游信号通路关键调控分子。我们的前期研究发现髓核细胞自分泌基质在诱导脂肪干细胞成髓核细胞定向分化中能上调Kindlin-2表达，证实其在干细胞成髓核诱导分化中发挥重要作用；并利用髓核细胞自身合成与分泌基质的功能，通过生物方法初步构建出一种具有良好理化及生物学特性的新型髓核细胞源性基质微球。本课题旨在研究该基质微球的可控构建方法，探讨髓核细胞自分泌基质在诱导脂肪干细胞成髓核定向分化中Kindlin-2调控TGF-β和Shh通路的关键分子机制，并据此获得集搭载和高效诱导能力于一体的髓核细胞源性活性微载体，评估其载荷脂肪干细胞后对退变椎间盘的修复效果。

生物支架是椎间盘组织工程的要素之一，但现有的生物支架无法高效诱导干细胞成髓核定向分化，其搭载干细胞难以达到理想的退变椎间盘修复效果。髓核细胞自分泌基质能通过与干细胞表面整合素受体结合，促进干细胞成髓核细胞定向分化；而Kindlin-2是整合素下游信号通路关键调控分子。因此本课题拟探讨髓核细胞自分泌基质在诱导脂肪干细胞成髓核定向分化中Kindlin-2调控TGF-β和Shh通路的关键分子机制，并据此利用髓核细胞自身合成与分泌基质的能力，通过生物方法构建集搭载和高效诱导能力于一体的髓核细胞源性活性微载体，评估其载荷脂肪干细胞后对退变椎间盘的修复效果。通过本课题的研究，我们发现Kindlin-2在脂肪干细胞分化早期先激活TGF-β通路，在分化中晚期激活Shh信号通路。据此基础，我们成功构建出髓核细胞源性活性微载体，该载体具有良好的生物学稳定性，合适的粒径，同时能有效促进脂肪干细胞成髓核细胞定向分化，最后我们在兔退变椎间盘动物模型中明确了该微载体搭载脂肪干细胞后具有良好的修复退变椎间盘的效果。本课题为新型生物材料的构建及退变椎间盘再生修复提供了新的切实可行的研究思路。