A Full-scaled Tissue Engineering Graft for Osteochondral Regeneration raw data

In this study we endeavoured to develop a full-scaled osteochondral graft with LhCG as the cartilage phase, PLGA scaffold as the subchondral phase, and a naturally formed interpentration network (IPN) that mimics the cartilage-bone interface. The IPN in the graft is formed by spontaneous migration of chondrocytes in LhCG into the porous PLGA scaffold. The decellularization potential of the full-scaled osteochondral graft will also be investigated in this study.

Collectively we have developed both cell-laden and decellularized full-scaled tissue engineered graft with a naturally formed cartilage-bone interpenetration zone and investigated their potential to repair traumatic osteochondral lesions. The anisotropic graft is characterized for its microarchitecture and biochemical composition. The osteochondral lesion repair capability was investigated within a rabbit osteochondral defect model by examining the mechanical property and biological property of the regenerated tissue.

The PLGA-SMS subchondral layer was integrated with scaffold-free cartilage layer sandwiching a transition zone to establish the cartilage-bone interface. Gelation of chondral layer on top of the porous subchondral bone layer mimics the osteochondral gradient in terms of biochemical composition and its micro-architecture. The secretion of ECM from native chondrocytes and the migration of chondrocytes into the porous SMS scaffold formed the layer specific osteochondral tissue zonal structure naturally. The decellularized version of the graft has been successfully derived as confirmed by the removal of cellular component and retention of ECM composition and its morphology. In the untreated defect no regeneration was observed in the cartilage layer and the tissue gradually degenerated. On the other hand, the biomimetic gradient LhCG+ scaffold exhibited superior tissue coverage at the defect macroscopically. Furthermore, histological analysis demonstrated the regeneration of both subchondral bone and cartilage tissue as evidenced by the same phenotype of neo-tissue when compared with the native healthy osteochondral tissue in the same zonal region. In addition, confined subchondral bone formation with bone volume to total defect volume similar to the native tissue was observed in the LhCG+ graft after 100 days of implantation within the animal model studies. Among the two types of graft, LhCG+ demonstrated a significantly higher Young’s modulus which suggested stronger load-bearing capacity of regenerated neo–tissue which is approximately 70% of native tissue mechanical strength. These results suggested that the engineered osteochondral mimetic cell laden full-scaled graft that comprises of cartilage layer, subchondral bone layer and gradient interface showed strong regenerative capabilities to repair osteochondral tissue defects.

在本项研究中，我们致力于开发一种全尺寸的骨软骨移植物，其中以LhCG作为软骨相，PLGA支架作为软骨下相，并构建了一种自然形成的相互渗透网络（IPN），以模拟软骨-骨界面。移植物中的IPN是通过软骨细胞在LhCG中的自发迁移进入多孔PLGA支架中形成的。本研究还将探究全尺寸骨软骨移植物的脱细胞化潜力。总体而言，我们已开发出既含有细胞又已脱细胞的全尺寸组织工程移植物，并研究了它们修复创伤性骨软骨损伤的潜力。异向移植物以其微观结构和生化组成而著称。通过在兔骨软骨缺陷模型中检测再生组织的力学性能和生物学性能，研究了骨软骨损伤修复能力。PLGA-SMS软骨下层与无支架的软骨层和过渡区相结合，以建立软骨-骨界面。软骨层在多孔软骨下骨层上的凝胶化模拟了骨软骨梯度在生化组成和微观结构方面的梯度。原代软骨细胞的细胞外基质（ECM）分泌和软骨细胞向多孔SMS支架的迁移形成了具有特定骨软骨组织区带结构的层。通过去除细胞成分并保留ECM组成及其形态，成功制备了移植物的脱细胞版本。在未经处理的缺陷中，软骨层未观察到再生，组织逐渐退化。另一方面，生物仿生梯度LhCG+支架在宏观上表现出优异的组织覆盖能力。此外，组织学分析表明，与同一区域区域的原代健康骨软骨组织相比，新生组织的表型相同，从而证实了软骨下骨和软骨组织的再生。此外，在动物模型研究中植入100天后，LhCG+移植物观察到限制性软骨下骨形成，其骨体积与总缺陷体积相似于原代组织。在两种移植物类型中，LhCG+的杨氏模量显著更高，这表明再生新生组织的承载能力更强，其强度约为原代组织机械强度的70%。这些结果表明，由软骨层、软骨下骨层和梯度界面组成的工程化骨软骨仿生细胞负载全尺寸移植物具有强大的再生能力，能够修复骨软骨组织缺陷。