Wogonin pretreatment of infrapatellar fat pad mesenchymal stem cell-derived exosomes advances articular cartilage repair in osteoarthritis.

Aims: Osteoarthritis (OA) is a chronic joint disorder characterized by progressive cartilage degeneration, inflammation, and subchondral bone remodelling. Herein, the role of exosomes (Exos) extracted from wogonin-pretreated infrapatellar fat pad mesenchymal stem cells (MSCsIPFP) was explored, and their ability to promote cartilage defect repair in OA was clarified. Methods: In this study, the therapeutic effects of wogonin on MSCsIPFP-derived Exos and OA chondrocytes were investigated in vitro, and a mouse OA model was studied in vivo. Human-derived chondrocytes and MSCsIPFP were isolated and cultured. These cells were characterized through morphological observation, toluidine blue staining, immunofluorescence staining, detection of stem cell surface markers, and induction of directed differentiation. DiI dye was used to label and trace MSCsIPFP-derived Exo (MSCsIPFP-Exo). Chondrocyte inflammation and the mouse OA model were induced using interleukin (IL)-1β and destabilization of the medial meniscus (DMM) surgery. To evaluate chondrocyte proliferation and apoptosis, cell counting kit (CCK)-8 assay and flow cytometry were conducted. Articular cartilage destruction in mice was assessed using haematoxylin and eosin (H&E) staining, Safranin O/Fast Green staining, and the Osteoarthritis Research Society International (OARSI) score. Additionally, immunohistochemical staining and/or western blot were performed to examine the expression of Sox9, aggrecan, type II collagen (collagen II), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), and matrix metalloproteinase 13 (MMP13). Results: The isolated chondrocytes could uptake MSCIPFP-Exo. Wogonin-MSCIPFP-Exo enhanced chondrocyte proliferation and suppressed apoptosis; Wogonin-MSCIPFP-Exo significantly alleviated cartilage tissue damage in OA mice compared to untreated controls and MSCIPFP-Exo-treated OA mice in in vivo experiments. Mechanistically, wogonin-MSCIPFP-Exo upregulated Sox9, aggrecan, and collagen II protein levels, while downregulating ADAMTS5 and MMP13 protein levels compared to untreated controls and MSCIPFP-Exo-treated OA mice. Conclusion: Wogonin pretreatment significantly enhances the ability of MSCIPFP-Exo to promote cartilage defect repair, and it is expected to be a promising agent for the clinical treatment of OA. Further preclinical and clinical studies are necessary to validate the safety, efficacy, and long-term outcomes of this therapeutic approach before its translation into clinical practice for the treatment of OA.