Integrated Osteochondral Microsphere Scaffolds with Biomimetic Architecture and Regional Vascularization for Joint Repair

Abstract

Osteochondral lesion potentially causes a variety of joint degenerative diseases if it cannot be treated effectively and timely. Microfracture as the first line surgical choice achieves limited results for the larger defect whereas cartilage patches trigger integrated instability and cartilage fibrosis. To tackle aforementioned issues, here we explore to construct an integrated osteochondral scaffold for synergetic regeneration of cartilage and subchondral bone in one system. On the macro level, we fabricated three integrated scaffolds with distinct channel structure of Non-channel, Consecutive-channel and Inconsecutive-channel via Selective Laser Sintering (SLS). On the micro level, cartilage zone and subchondral bone zone of integrated scaffold consisted of small polycaprolactone (PCL) microspheres with the diameter of 50 μm and large PCL microspheres with the diameter of 150 μm, respectively. As a result, cartilage zone exhibited a dense phase for the inhibition of vessel invasion while subchondral zone generated a porous phase for the ingrowth of bone and vessel. Our findings showed that Inconsecutive-channel scaffolds possessed biomimetic hierarchical structure, adequate mechanical properties, gradient interconnected porosity in comparison with Non-channel and Consecutive-channel groups. Moreover, Inconsecutive-channel scaffolds obviously induced cartilage regeneration and subchondral bone remodeling. Consequently, this work not only achieves an effective and regeneratable microsphere scaffold for osteochondral reconstruction, but also provides a feasible methodology to recover injured joint through integrated design pattern. Funding Information: This work was financially supported by the National Key Research and Development Program of China (2017YFC1103900), the National Natural Science Foundation of China (32171323, 91939111), Key Research and Development Program of Hubei Province (2020BCB056), International Science and Technology Cooperation Projects of Shenzhen (GJHZ20200731095211035), Sanming Project of Medicine in Shenzhen (SZSM201812055), and the Fundamental Research Funds for the Central Universities (2019kfyRCPY103). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: All procedures for animal experiments were approved by the Institutional Animal Care and Use Committee of Huazhong University of Science and Technology (SYXK20170094).