生物3D打印构建Wnt/β-catenin通路双向调节支架引导关节软骨-软骨下骨一体化修复的作用与机制研究

在关节骨软骨缺损的一体化修复过程中，如何提高3D打印支架的生物活性，诱导上层透明软骨再生并维持其表型，同时促进软骨下骨快速生成是当前组织工程研究的重点和难点。课题组前期研究发现BMP-7与Wnt/β-catenin通路的抑制剂IWP-2序列刺激能够促进干细胞向透明软骨分化并维持其表型，而BMP-7与Wnt/β-catenin通路的促进剂poly-P序列刺激能够诱导干细胞发生软骨内成骨。鉴此，本研究聚焦BMP-7协同Wnt/β-catenin通路的双向调节，提出了通过海藻酸钠微球核壳分层装载BMP-7与IWP-2或poly-P用以制备软骨相及骨相生物墨水，采用3D生物打印技术一体化构建结构与成分差异化、细胞高负载的骨软骨复合支架，通过系统性研究该复合支架的理化性能、在透明软骨诱导及维持、骨快速发生中的促进作用及可能的分子机制，为临床上构建新型软骨-软骨下骨缺损一体化修复材料提供实验依据。

Articular cartilage and subchondral bone defects severely destruct the structural integrity and biofunction of the joint. How to prepare a bifunctional scaffold, which is capable of inducing the regeneration of hyaline cartilage and subchondral bone simultaneously, still remains a great challenge in tissue engineering. BMP-7 is an important stimulator for cartilage regeneration. However, it may cause chondrocyte hypertrophy and ossification. Our team's previous research found that BMP-7 interacted with the Wnt/β-catenin pathway inhibitor IWP-2 or the promoter poly-P could induce bone marrow mesenchymal stem cells (BMSCs) to differentiate into cartilage and osteogenesis respectively. Based on this, we proposed that the positive or negative activation of Wnt/β-catenin pathway after the stimulation of BMP-7 may promote the regeneration of cartilage and subchondral bone simultaneously. To test this hypothesis, double layered alginate particles loading with BMP-7 in core and IWP-2 or poly- P on the surface, is designed to mix with the bio-inks (chondroitin sulfate) for fabrication of cartilage and bone respectively. Then, a structurally differentiated and heterogeneous osteochondral scaffold will be prepared with 3D bioprinting technology. Furthermore, systematic research on induction and maintenance of hyaline cartilage and rapid bone formation will be carried out. In conclusion, the promotive effect and the investigation of the possible underlying mechanism in the present study may provide experimental basis for constructing a new cartilage-subchondral scaffolds in clinical.