Bionic Biphasic Composite Scaffold with Osteochondrogenic Factors for Regeneration of Full-Thickness Osteochondral Defect

Full-thickness osteochondral defects lack the capability to self-repair owing to their complicated hierarchical structure. At present, clinical treatments including microfracture etc. have shown some efficacy; however, the newborn tissue exhibits some drawbacks, such as fibrocartilage formation and insufficient mechanical properties, eventually leading to osteoarthritis. Moreover, cartilage and bone tissues have different biological characteristics. Therefore, the simultaneous repair of full-thickness osteochondral defects is highly challenging. To achieve optimal repair, we constructed a bionic biphasic composite scaffold with on-demand osteochondrogenic factors. Kartogenin and extractive mesenchymal stem cells were introduced into a mPEG- block -poly(L-valine) thermogel set as the upper layer to accelerate cartilage repair. A poly(lactide- co -glycolide)/hydroxyapatite porous scaffold was immobilized with bone morphogenetic protein-2 as the bottom layer to facilitate subchondral repair. The intermediate interface, being a combination of the two layers was expected to reconstruct the calcification zone. Gross evaluation, micro-computed tomography, and magnetic resonance imaging indicated that at 6 months after implantation, the scaffold encapsulating mesenchymal stem cells and osteochondrogenic factors had a better effect compared with other groups. More importantly, the composition of the new cartilage and bone was confirmed by western blotting, H&E staining, immunohistochemistry, and immunofluorescence. Taken together, this bionic composite scaffold with osteochondrogenic factors offers a promising option for the repair of full-thickness osteochondral defects.Funding Information: Funding for this study was supported by National Natural Science Foundation of China grants (81671804, 81701811) and Natural Science Foundation of Jilin Province (20200201322JC).Declaration of Interests: The authors declare no conflict of interest.Ethics Approval Statement: This experiment was carried out in the facilities of the Experimental Animal Center of Jilin University, and was carried out under the supervision of the Animal Ethical Welfare Committee of Jilin University, in compliance with the requirements of Jilin University and the state for the ethical welfare of experimental animals.