Synovial mesenchymal stem cell-derived exosomal miR-320c enhances chondrogenesis by targeting ADAM19

Background: Synovial mesenchymal stem cell (SMSC)-derived exosomes show treatment potential in osteoarthritis, although their functional mechanism is still unclear. Materials & methods: Osteoarthritis chondrocytes and normal SMSC were cultured. Subsequently, chondrocytes were co-cultured with SMSC or miR-320c-overexpressing SMSC-derived exosomes, or directly transfected with miR-320c mimic. Furthermore, compensate experiments were conducted. Results: SMSC promoted chondrocyte proliferation, migration, COL2A1 and ACAN expressions while suppressing apoptosis by transmitting exosomes. Furthermore, miR-320c-overexpressing SMSC-derived exosomes and direct miR-320c overexpression in chondrocytes presented more significant effect on enhancing chondrogenesis. In addition, miR-320c directly targeted ADAM19, and ADAM19 overexpression compensated the regulation of miR-320c on chondrogenesis. Conclusion: SMSC-derived exosomal miR-320c enhances chondrogenesis through targeting ADAM19, highlighting a potentially novel mechanism of SMSC in treating osteoarthritis.

LncRNA Malat-1 From MSCs-Derived Extracellular Vesicles Suppresses Inflammation and Cartilage Degradation in Osteoarthritis

Purpose: Extracellular Vesicles (EVs) derived from hMSCs, have the potential to alleviate cartilage damage and inflammation. We aimed to explore the effects of EVs derived from lncRNA malat‐1-overexpressing human mesenchymal stem cells (hMSCs) on chondrocytes.Material and Methods: hMSCs-derived Extracellular Vesicles (hMSCs-EVs) were identified by transmission electron microscopy and western blot. We used a Sprague-Dawley (SD) rat model of CollagenaseⅡ-induced osteoarthritis (OA) as well as IL-1β-induced OA chondrocytes. Lentiviral vectors were used to overexpress lncRNA malat‐1 in hMSCs. Chondrocyte proliferation, inflammation, extracellular matrix degradation, and cell migration were measured by Edu staining, ELISA, western blot analysis, and transwell assay. Chondrocyte apoptosis was evaluated by flow cytometry, Hoechst 33342/PI Staining, and western blot. Safranine O-fast green (S-O) staining and HE staining were used to assess morphologic alterations of the rat knee joint.Results: hMSCsmalat−1-EVs decreased MMP-13, IL-6, and Caspase-3 expression in IL-1β-induced OA chondrocytes. Moreover, hMSCsmalat−1-EVs promoted chondrocyte proliferation and migration, suppressed apoptosis, and attenuated IL-1β-induced chondrocyte injury. Our animal experiments suggested that hMSCsmalat−1-EVs were sufficient to prevent cartilage degeneration.Conclusion: Our findings show that lncRNA malat-1from hMSCs‐delivered EVs can promote chondrocyte proliferation, alleviate chondrocyte inflammation and cartilage degeneration, and enhance chondrocyte repair. Overall, hMSCsmalat−1-EVs might be a new potential therapeutic option for patients with OA.

Circular RNA mmu_circ_0001598 Contributes to IL-1β-Induced Osteoarthritis Progression by Regulating miR-127-3p

Osteoarthritis (OA), a chronic disease characterized by articular cartilage degeneration, is a leading cause of disability and pain worldwide. Accumulating evidence indicates that circular RNAs (circRNAs) play a critical role in various diseases, but the function of circRNAs in OA remains largely unknown. In this study, we found that circ_0001598 was significantly upregulated in chondrocytes treated with IL-1β and in cartilage tissue from mice with severed anterior cruciate ligament surgery (ACLT) induced OA models. Interference with circ_0001598 in vitro restored IL-1β-induced chondrocyte proliferation and apoptosis. Silencing circ_0001598 significantly alleviated ACLT-induced OA in mice. Mechanistically, knockdown of circ_0001598 affected chondrocyte proliferation, apoptosis, and matrix degradation by regulating miR-127-3p. Taken together, our results demonstrate the fundamental role of circ_0001598 and provide new ideas for the prevention and treatment of osteoarthritis.

Intra-articular injection of loaded sPL sustained-release microspheres inhibits osteoarthritis and promotes cartilaginous repairs

Background Osteoarthritis is a chronic inflammatory disease of the joints associated with significant morbidity and lower quality of life. Current treatment strategies focus on reducing cartilage degeneration but fail to restore their proliferative ability. Super-activated platelet lysate (sPL) is an enhanced form of platelet-rich plasma that can be easily inactivated. The purpose of this study is to evaluate whether sPL-loaded PLGA/chitosan/gelatin microspheres can prevent and treat osteoarthritis. Methods Features of biological microspheres were detected by SEM and ELISA. Osteoarthritis chondrocytes were co-cultured with hydrogel loaded with sPL. The effect of biological microspheres on chondrocyte proliferation was evaluated using a CCK-8 cell proliferation test. Cell morphology and cell necrosis were measured with a microscope. The gene expression levels of cartilage-related markers type 2 collagen, aggrecan (ACAN), and SRY type high mobility group box-9 (SOX9) were determined by real-time quantitative polymerase chain reaction (Rt-PCR). A rat osteoarthritis model was established. Micro-CT was used to characterize cartilaginous changes after the injection of biological microspheres. Histopathological HE staining, Safranin-O Fast Green staining and staining scores, type II collagen staining, and proteoglycan staining were used to evaluate the degree of cartilaginous repair. Results Biological microspheres were able to continuously release biological factors. Exposure to loading sPL microspheres significantly increased chondrocyte proliferation, reduced cell necrosis, and increased the expression of cartilage markers type 2 collagen, ACAN, and SOX9 in osteoarthritic chondrocytes. In vivo experiments found that biological microspheres also smoothen cartilage surfaces, promote the expression of proteoglycan and type 2 collagen while also increasing cartilaginous integrity as evaluated using Safranin-O Fast Green staining. Conclusions PLGA/chitosan/gelatin hydrogel loaded with sPL is a promising tool for effective and non-invasive articular cartilage repair in osteoarthritis. Graphic abstract Biological microspheres loaded with sPL release various biological factors to promote chondrocyte proliferation and upregulate chondrocyte functionalization genes (SOX9, CoX II, ACAN), leading to an overall enhanced cartilaginous matrix.

Fibonacci Sequence-related Phenomenon During Chondrocyte Proliferation of the Gottingen Pig Knee Tibial Plateau

Background The aim of our study was to observe the quantitative changes in tibial plateau chondrocytes in the proliferation process from normal Gottingen pigs in vitro and compare them with the Fibonacci sequence.Methods Chondrocytes from normal Gottingen pig tibial plateau cartilage were isolated and cultured to the third generation, and the number of chondrocytes was measured to determine whether the chondrocyte growth was at the logarithmic growth phase. Chondrocytes were added to cell culture bottles at very a low density to allow full separation and allow each chondrocyte to grow as independently as possible. Thirty single chondrocytes were selected, and the number of chondrocyte colonies were observed and recorded every day. Results Among the 30 chondrocyte colonies, the changes in the numbers of 16 chondrocyte colonies were 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, and 987, which conformed to the numbers of the Fibonacci sequence.The number of other chondrocyte colonies was lower than corresponding numbers of the Fibonacci sequence at the same time point.Conclusion The numbers of normal Gottingen pig tibial plateau chondrocytes during the proliferation process were in line with the numbers of the Fibonacci sequence.Alignment to the Fibonacci sequence may be the fastest way for changes in the numbers of normal chondrocytes during the proliferation process in vitro.

Hesperetin Exhibits Anti-Inflammatory Effects on Chondrocytes via the AMPK Pathway to Attenuate Anterior Cruciate Ligament Transection-Induced Osteoarthritis

This study aimed to determine whether hesperetin (HPT) has chondroprotective effects against the TNF-α-induced inflammatory response of chondrocytes and related mechanisms and clarify the impact of HPT on osteoarthritis (OA) induced by anterior cruciate ligament transection (ACLT). Under tumor necrosis factor-α (TNF-α) stimulation, rat chondrocytes were treated with or without HPT. The CCK-8 assay was used to detect viability and cytotoxicity. RT-qPCR and Western blot were used to examine the expression of aggrecan, collagen type II, and inflammatory and proliferative genes/proteins in chondrocytes. Flow cytometry was used to check the cell cycle to determine whether HPT protects chondrocytes against the inhibitory effect of TNF-α on chondrocyte proliferation. In addition, RNA sequencing was used to discover possible molecular targets and pathways and then validate these pathways with specific protein phosphorylation levels. Finally, immunofluorescence staining was used to examine the phosphorylation of the AMP-activated protein kinase (AMPK) pathway. The results showed that HPT restored the upregulation of interleukin 1β (IL-1β), PTGS2, and MMP-13 induced by TNF-α. In addition, HPT reversed the degradation of the extracellular matrix of chondrocytes induced by TNF-α. HPT also reversed the inhibitory effect of TNF-α on chondrocyte proliferation. RNA sequencing revealed 549 differentially expressed genes (DEGs), of which 105 were upregulated and 444 were downregulated, suggesting the potential importance of the AMPK pathway. Progressive analysis showed that HPT mediated the repair of TNF-α-induced chondrocyte damage through the AMPK signaling pathway. Thus, local treatment of HPT can improve OA induced by ACLT. These findings indicated that HPT has significant protective and anti-inflammatory effects on chondrocytes through the AMPK signaling pathway, effectively preventing cartilage degradation. Given the various beneficial effects of HPT, it can be used as a potential natural drug to treat OA.

Distinct roles of glutamine metabolism in benign and malignant cartilage tumors with IDH mutations

Enchondromas and chondrosarcomas are common cartilage neoplasms that are either benign or malignant respectively. The majority of these tumors harbor mutations in either IDH1 or IDH2. Glutamine metabolism has been implicated as a critical regulator of tumors with IDH mutations. Chondrocytes and chondrosarcomas with mutations in the IDH1 or IDH2 genes showed enhanced glutamine utilization in downstream metabolism. Using genetic and pharmacological approaches, we demonstrated that glutaminase-mediated glutamine metabolism played distinct roles in enchondromas and chondrosarcomas with IDH1 or IDH2 mutations. Deletion of glutaminase in chondrocytes with Idh1 mutation increased the number and size of enchondroma-like lesions. Pharmacological inhibition of glutaminase in chondrosarcoma xenografts reduced overall tumor burden. Glutamine affected cell differentiation and viability in these tumors differently through different downstream metabolites. During murine enchondroma-like lesion development, glutamine-derived α-ketoglutarate promoted hypertrophic chondrocyte differentiation and regulated chondrocyte proliferation. In human chondrosarcoma, glutamine-derived non-essential amino acids played an important role in preventing cell apoptosis. This study reveals that glutamine metabolism can play distinct roles in benign and malignant cartilage tumors sharing the same genetic mutations. Inhibiting GLS may provide a therapeutic approach to suppress chondrosarcoma tumor growth.