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Background: The pathogenesis of osteoarthritis (OA) involves the progressive degradation of articular cartilage. Exosomes derived from mesenchymal stem cells (MSC-EXOs) have been shown to mitigate joint pathological injury by attenuating cartilage destruction. Optimization the yield and therapeutic efficacy of exosomes derived from MSCs is crucial for promoting their clinical translation. The preconditioning of MSCs enhances the therapeutic potential of engineered exosomes, offering promising prospects for application by enabling controlled and quantifiable external stimulation. This study aims to address these issues by employing pro-inflammatory preconditioning of MSCs to enhance exosome production and augment their therapeutic efficacy for OA., Methods: The exosomes were isolated from the supernatant of infrapatellar fat pad (IPFP)-MSCs preconditioned with a pro-inflammatory factor, TNF-α, and their production was subsequently quantified. The exosome secretion-related pathways in IPFP-MSCs were evaluated through high-throughput transcriptome sequencing analysis, q-PCR and western blot analysis before and after TNF-α preconditioning. Furthermore, exosomes derived from TNF-α preconditioned IPFP-MSCs (IPFP-MSC-EXOs TNF-α ) were administered intra-articularly in an OA mouse model, and subsequent evaluations were conducted to assess joint pathology and gait alterations. The expression of proteins involved in the maintenance of cartilage homeostasis within the exosomes was determined through proteomic analysis., Results: The preconditioning with TNF-α significantly enhanced the exosome secretion of IPFP-MSCs compared to unpreconditioned MSCs. The potential mechanism involved the activation of the PI3K/AKT signaling pathway in IPFP-MSCs by TNF-α precondition, leading to an up-regulation of autophagy-related protein 16 like 1(ATG16L1) levels, which subsequently facilitated exosome secretion. The intra-articular administration of IPFP-MSC-EXOs TNF-α demonstrated superior efficacy in ameliorating pathological changes in the joints of OA mice. The preconditioning of TNF-α enhanced the up-regulation of low-density lipoprotein receptor-related protein 1 (LRP1) levels in IPFP-MSC-EXOs TNF-α , thereby exerting chondroprotective effects., Conclusion: TNF-α preconditioning constitutes an effective and promising method for optimizing the therapeutic effects of IPFP-MSCs derived exosomes in the treatment of OA., (© 2024. The Author(s).)

Here we present an efficient method for isolating and culturing mandibular bone marrow mesenchymal stem cells (mBMSCs) in vitro to rapidly obtain numerous high-quality cells for experimental requirements. mBMSCs could be widely used in therapeutic applications as tissue engineering cells in case of craniofacial diseases and cranio-maxillofacial regeneration in the future due to the excellent self-renewal ability and multi-lineage differentiation potential. Therefore, it is important to obtain mBMSCs in large numbers. In this study, bone marrow was flushed from the mandible and primary mBMSCs were isolated through whole bone marrow adherent cultivation. Furthermore, CD29 + CD90 + CD45 - mBMSCs were purified through fluorescent cell sorting. The second generation of purified mBMSCs were used for further study and displayed potential in differentiating into osteoblasts, adipocytes, and chondrocytes. Utilizing this in vitro model, one can obtain a high number of proliferative mBMSCs, which may facilitate the study of the biological characteristics, the subsequent reaction to the microenvironment, and other applications of mBMSCs.

There is a growing body of evidence indicating an association between osteoporosis and vascular diseases, which are associated with reduced blood supply. Decreased vascular flow results in a hypoxic gradient in the local microenvironment, affecting local bone remodeling. Bone mesenchymal stem cells (BMSCs) have been demonstrated to be the key to bone remodeling. To elucidate the molecular mechanisms involved in vascular supply and osteoporosis, the present study investigated the effect of hypoxia on BMSCs in vitro during osteogenesis. The BMSC osteogenesis process was evaluated by alkaline phosphatase (ALP) activity assay and the mRNA expression of the osteogenic markers runt‑related transcription factor 2 (Runx2), ALP and osteocalcin. The function of extracellular signal‑regulated kinase (ERK)1/2 and p38 kinase were studied under hypoxia using specific inhibitors. The results demonstrated that hypoxia reduces the osteogenic differentiation of BMSCs by inactivating Runx2, followed by decreased ALP activity and mRNA expression levels of ALP, collagen type I and osteocalcin. Furthermore, these data suggested that the ERK1/2 and p38‑mitogen activated protein kinase signaling pathways might participate in hypoxia‑induced differentiation of BMSCs toward the osteogenic phenotype. Compared with ERK1/2, the p38‑Runx2 signaling pathway might exert a relatively more prominent effect in the above process. These findings may help to elucidate the pathophysiology of osteoporosis caused by decreased vascular supply.

Objectives: Alveolar bone osteoporosis has attracted more and more attention because of its profound impact on stomatognathic function and treatment, but current treatments have not been targeted to alveolar bone and might even cause severe side effects. Thus, identifying the effects of anti‐osteoporosis agents on alveolar bone is essential. Icariin ameliorates metabolic dysfunction of long bones, but its effects on alveolar bone remain unclarified. Materials and methods: BMSCs were isolated from rat mandibles (mBMSCs). The osteogenic potential of mBMSCs and the signalling pathway involved under icariin treatment were measured by ALP and alizarin red staining, reverse transcription‐polymerase chain reaction (RT‐PCR), Western blotting and immunofluorescence. Dual‐luciferase assay, chromatin immunoprecipitation (ChIP) and co‐immunoprecipitation were used to investigate the molecular mechanism. Ovariectomized and sham‐operated rats treated with or without icariin were analysed by micro‐CT, TRAP staining and calcein double labelling. Results: We found that icariin promoted osteoblast differentiation of mBMSCs. Furthermore, STAT3 was critical for icariin‐promoted osteoblast differentiation, as indicated by increased phosphorylation levels in icariin‐treated mBMSCs, while preventing STAT3 activation blocked icariin‐induced osteoblast differentiation. Mechanistically, icariin‐promoted transcription of the downstream osteogenic gene osteocalcin (Ocn) through STAT3 and STAT3 bound to the promoter of Ocn. Notably, icariin prevented the alveolar bone osteoporosis induced by oestrogen deficiency through promoting bone formation. Conclusions: For the first time, our work provides evidence supporting the potential application of icariin in promoting osteogenesis and treating alveolar bone osteoporosis. [ABSTRACT FROM AUTHOR]