Repair of Osteochondral Defect with Acellular Cartilage Matrix and Thermosensitive Hydrogel Scaffold.

Abstract

In the present study, acellular cartilage matrix (ACM) was modified with poly-l-lysine/hyaluronic acid (PLL/HA) multilayers via detergent-enzyme chemical digestion and layer-by-layer self-assembly technology. This modified ACM was then loaded with Transforming Growth Factor Beta 3 (TGF-β3) and incorporated into a thermosensitive hydrogel (TH) to create a HA/PLL-ACM/TH composite scaffold with sustained-release function. This study aimed to evaluate the efficacy of this novel composite scaffold in promoting chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and facilitating osteochondral defect repair. <i>In vitro</i>, isolated, and cultured rat BMSCs were inoculated in equal amounts into TH, ACM/TH, and HA/PLL-ACM/TH groups, with or without TGF-β3 supplementation, for 21 days. Western blot (WB) analysis and immunofluorescence staining were employed to assess the expression levels of collagen II, aggrecan, and SOX-9. <i>In vivo</i>, osteochondral defect was created in the Sprague-Dawley rat trochlea using microdrilling. TH, ACM/TH, and HA/PLL-ACM/TH scaffolds, with or without TGF-β3, were implanted into the defect. After 6 weeks, the repairs were evaluated macroscopically, using Micro computed tomography (micro-CT), histological analysis, and immunohistochemistry. The results demonstrated that the HA/PLL-ACM/TH scaffold loaded with TGF-β3 significantly upregulated the expression of collagen II, aggrecan, and SOX-9 compared with the control and other experimental groups. Furthermore, at 6 weeks postsurgery, the HA/PLL-ACM/TH group loaded with TGF-β3 exhibited superior tissue formation on the joint surface, as confirmed by micro-CT and histological evidence, indicating improved osteochondral repair. These findings suggest that the HA/PLL-ACM/TH scaffold loaded with TGF-β3 holds promise as a therapeutic strategy for osteochondral defect and offers a novel approach for utilizing acellular cartilage microfilaments.