Intra-articular Injection of Ascorbic Acid Enhances microfracture-mediated Cartilage Repair

Abstract

Objective:Previous studies have confirmed that Ascorbic Acid(AA) can promote cartilage repair and improve cartilage differentiation of bone marrow mesenchymal stem cells. However, the use of microfractures(MFX) combined with AA in the repair of cartilage damage has not been studied. The aim of this study is to explore the beneficial effects of the combination of MFX and AA in cartilage repair. Methods:Sixty New Zealand white rabbits were randomly divided into 5 groups (12 knees each): MFX group and MFX combined with 4 different concentrations of AA treatment group (1mg/ml, 3mg/ml, 10mg/ml, 30mg/ml). Construct a rabbit knee trochlear groove osteochondral defect (diameter 5 mm, depth 2 mm), and perform MFX surgery after the osteochondral defect. Inject different concentrations of AA into both knee joint cavities immediately, 2 weeks, and 4 weeks after surgery. At 6 and 12 weeks after surgery, rabbits were euthanized for gross observation, International Cartilage Repair Society (ICRS) score, micro-computed tomography examination, histological and immunohistochemical detection, and reverse transcription quantitative polymerase chain reaction was used to detect the expression of TGF-β1, AKT/Nrf2, and VEGF mRNA. Results:After 6 weeks of surgery, gross observation and Micro-CT showed that compared to MFX, the 10mg/ml group had better healing of cartilage defect areas and subchondral bone, with higher ICRS scores, while the 30mg/ml group had lower ICRS scores; Histology and immunohistochemistry showed that compared to MFX, the 10mg/ml regenerated cartilage had a higher thickness and type 2 collagen content, while the 30mg/ml group showed a small amount of regenerated cartilage and higher type 1 collagen expression. At 12 weeks after surgery, gross observation, histology, and immunohistochemistry showed the same results as at 6 weeks, with 10mg/ml exhibiting more transparent morphology. Quantitative polymerase chain reaction results showed that after AAinjection, the mRNA levels of TGF and VEGF were significantly downregulated. Conclusion:Injection of AA into the joint cavity has a positive effect on cartilage repair mediated by MFX. Among them, when the injection concentration of AA is 10mg/ml, it is the most effective in promoting cartilage repair mediated by MFX; Meanwhile, intra-articular injection of AA promotes the synthesis of type II collagen and the formation of glycosaminoglycans by downregulating the mRNA expression levels of TGF-β1 and VEGF.