超分子水凝胶作为干细胞及小分子药物载体治疗关节软骨缺损的关键技术研发

Objectives: to develop self-healing, bioadhesive, and mechanically resilient supramolecular gelatin hydrogels for articular cartilage repair..Motivation: hydrogels are ideal carrier material for the delivery of therapeutic cells (like stem cells) and drugs to enhance the healing and regeneration of damaged biological tissues/organs. However, conventional chemically crosslinked hydrogels have a number of limitations that hinder the clinical translation of these hydrogels. In this project, we aim to develop novel supramolecular hydrogels, which are free of chemical crosslinking and have an array of unique features that are desirable for potential clinical applications. .Methodology: supramolecular hydrogel are generally mechanically weak. We have developed a novel “Host-guest macromer” (HGM) approach to fabricate supramolecular hydrogels with enhanced mechanical properties. Briefly, premixing the free diffusing crosslinkable host molecules with the polymer containing guest motifs significantly enhance the host-guest complexation efficiency due to the low steric hindrance. The subsequent polymerization of the obtained “HGM” produces the supramolecular hydrogels that are highly stretchable and self-healable. Furthermore, the residual hydrophobic cavities of the host molecules in the hydrogels afford the potential for facile modular modifications such as incorporation of hydrophobic drugs and tethering of bioactive molecules. .Impact & benefit: the advantages of the proposed HGM supramolecular hydrogels compared to existing products include mechanical resilience, tissue adhesiveness, self-healing, ease of use, and capability of delivering hydrophobic drugs. These benefits make the proposed hydrogels ideal vehicles for delivering therapeutic cells and drugs to assist treatments of human cartilage defects and a variety of other diseases including spinal cord injury, intervertebral disc herniation, and tendinopathy.

近年来，人骨髓间充质干细胞以及小分子药物由于其各项优点，已成为广泛关注的修复关节软骨的治疗手段。然而，直接植入干细胞或注射小分子药物到软骨缺损部位的治疗效果通常并不理想。这是由于在没有三维生物材料保护下，干细胞在体内的存活率低；同时小分子药物的流失很快，因此起不到应有的疗效。本项目拟开发新型可注射超分子明胶水凝胶作为干细胞及小分子药物的载体用来修复关节软骨缺损。计划使用一种新型制备超分子水凝胶的方法，“主客体大分子”方法，来制备高力学性能的超分子明胶水凝胶。同时项目还将优化超分子水凝胶设计，使其具有良好的生物兼容性、有自我修复能力、凝胶状态下可注射性、使用简单、可缓释疏水性小分子药物、组织粘附性、支持干细胞软骨分化等优良特性。项目计划在动物关节软骨缺损模型中测试超分子明胶水凝胶作为干细胞及小分子药物载体修复软骨缺损的功效。所开发水凝胶还可用于韧带损伤、脊髓损伤、椎间盘突出等疾病的治疗。

近年来，骨关节炎的年发病人数逐年增长，已成为致残的主要疾病之一，给患者和社会带来严重的经济损失。然而，直接植入干细胞或注射小分子药物到软骨缺损部位的治疗效果通常并不理想。最新的自体软骨细胞体外增殖后植入软骨缺损部位的疗法也面临诸多问题，如不可注射，黏附性差和自我修复能力弱等缺点。因此，可负载间充质干细胞并包埋小分子药物的超分子水凝胶成为干细胞疗法的优良载体。本项目旨在开发新型基于主客体作用形成的超分子明胶水凝胶，解决限制现有可注射水凝胶在关节软骨修复应用方面的部分问题。本项目合成了具有不同丙烯化程度的环糊精，并以此与明胶通过主客体作用复合制备了超分子水凝胶，研究了其力学性能，自修复能力和组织粘附性等关键指标。本项目证明了该水凝胶是生长因子和小分子药物的缓释载体，并可在还是过程中保持其生物活性。进一步地，本项目评估了其作为间充质干细胞载体的生物相容性，并研究了其支持负载的间充质干细胞成软骨分化的作用。最后，我们测试了该水凝胶在动物软骨缺损模型中的修复效果。本项目获得了一系列研究进展，并展示了其可能的应用前景。本项目经过反复地实验得到了丙酰化环糊精的成熟稳定的制备及表征方法，成功制备了明胶基超分子水凝胶，并在此基础上开展了一系列针对该超分子水凝胶性质的研究。该明胶基超分子水凝胶可被注射到不规则的软骨缺损部位，并很好地粘附到周围的软骨上，显示了高度可调的力学性能和良好的自修复性能。该水凝胶具有缓释生长因子和小分子药物的能力，研究表明，其可以在28天内持续释放具有软骨诱导活性的诱导剂。对负载有间充质干细胞和小分子药物的超分子水凝胶的体外和体内实验表明该水凝胶可以有效地支持负载的间充质干细胞向软骨细胞方向分化，并可以促进软骨基质的形成。更进一步，该水凝胶在小动物兔子和大动物猪中均具有良好的软骨缺损修复效果，可显著地增强关节透明软骨的再生。