功能化自组装多肽水凝胶诱导髓核间充质干细胞修复椎间盘的作用及其机制

Intervertebral disc degeneration is a main cause of neck-shoulder pain, low back pain and leg pain. Currently, conservative and surgical treatments are the main managements for intervertebral disc degeneration. But both of them are aiming at symptomatic relief, not the causal treatment. The application of tissue engineering cherishes the hope to fundamental alleviation and even reverses the intervertebral disc degeneration. However, the traditional tissue engineering intervertebral disc constructed in vitro, and then put into vivo, has many limitations. By contrast, the discovery of nucleus pulposus mesenchymal stem cells (NP-MSCs) from nucleus pulposus nowadays, gives the possibility to construct the tissue engineering intervertebral disc in vivo. Initially, RADA16-I is an injectable and self-assemble into a well-ordered hydrogel-like nanofiber scaffold in vivo. More significantly, self-assembling peptide scaffold can be functionalized directly through solid-phase synthesis extension at the C-termini of RADA16-I with short sequences. Therefore, this study uses the RADA16-I to construct the functional self-assembling peptide nanofiber scaffolds with the different short peptides which have the biological functions of BMP7. Then the scaffolds are injected into degenerative intervertebral discs. The purpose of this study is to explore whether the functional self-assembling peptides induce proliferation, differentiation, migration of NP-MSCs as well as secretion of extracellular matrix to restore the homeostasis of intervertebral disc endogenously. Furthermore, this study will explore the possible mechanism of regeneration and repair of intervertebral disc by the functional self-assembling peptides. Meanwhile, this new technique of tissue engineering nucleus pulposus constructed in vivo would be established, and provide a new concept of tissue engineering to other fields.

椎间盘退变是颈肩腰腿痛的主要病因。由于椎间盘退变的机制不清，除对症治疗外，通过组织工程技术延缓甚至逆转椎间盘退变，是最有前途的治疗思路。传统的“体外构建-体内植入”的组织工程方法有其局限性。文献报道和我们前期研究证实了椎间盘内髓核间充质干细胞（NP-MSCs）的存在并具有多向分化潜能；RADA16-I是一种特殊的可注射自组装多肽，已广泛用于再生医学领域。本研究拟在自组装多肽水凝胶RADA16-I的C端插入具有特殊功能的BMP7短肽片段构建功能化自组装多肽水凝胶。通过微创技术将具有BMP7活性的功能化自组装多肽原位注入退变椎间盘中，在体内自组装构建组织工程髓核，诱导椎间盘内的NP-MSCs增殖、分化、迁移，促进细胞外基质合成分泌，达到内源性修复椎间盘退变的目的。同时探索功能化自组装多肽内源性修复椎间盘的生物学机制。本研究可为组织工程技术的应用提供一种新的理念与方法，具有重要的理论和临床意义。

椎间盘退变（intervertebral disc degeneration，IDD）是因髓核蛋白多糖的丢失、细胞外基质（extracellular matrix，ECM）合成减少、椎间盘细胞逐渐衰老和凋亡而引发的一个主要病理过程，它给患者带来巨大痛苦的同时，也给社会和家庭带来了沉重的经济负担。对于该疾病的治疗，目前仍缺乏有效的治疗手段。因此，IDD的治疗成为了现今乃至将来我国医疗卫生领域亟待解决的难题之一。.通过组织工程技术延缓甚至逆转椎间盘退变，是最有前途的治疗思路。传统的“体外构建-体内植入”的组织工程方法有其局限性。文献报道椎间盘内髓核间充质干细胞（NP-MSCs）的存在并具有多向分化潜能；RADA16-I是一种特殊的可注射自组装多肽。本研究拟在自组装多肽水凝胶RADA16-I的C端插入具有特殊功能的BMP7短肽片段构建功能化自组装多肽水凝胶RADKPS。将具有BMP7活性的功能化自组装多肽RADKPS原位注入退变椎间盘中，在体内自组装构建组织工程髓核，诱导椎间盘内的NP-MSCs增殖、分化、迁移，促进细胞外基质合成分泌，达到内源性修复椎间盘退变的目的。同时探索功能化自组装多肽内源性修复椎间盘的生物学机制。.本研究已完成以下三项目标：1.以自组装多肽RADA16-I 为基本的组装单元，构建三种含有不同BMP7 功能短肽片段的功能化自组装多肽水凝胶材料，并筛选出一种物理学及生物学活性最佳的功能化自组装多肽水凝胶RADKPS。2.观察RADKPS 体内外趋化迁移及激活NP-MSCs 的生物学效应，及其修复不同程度退变椎间盘的效果，为椎间盘退变性疾病的治疗提供一种新的生物学治疗途径，并为生物学领域组织工程技术提供一种新的研究思路。3.明确RADA16-X 趋化诱导NP-MSCs 向类髓核细胞分化的可能机制。