Extracellular vesicles derived from mesenchymal stem cells mediate extracellular matrix remodeling in osteoarthritis through the transport of microRNA-29a.

BACKGROUND: Knee osteoarthritis (KOA) is a common orthopedic condition with an uncertain etiology, possibly involving genetics and biomechanics. Factors like changes in chondrocyte microenvironment, oxidative stress, inflammation, and immune responses affect KOA development. Early-stage treatment options primarily target symptom relief. Mesenchymal stem cells (MSCs) show promise for treatment, despite challenges. Recent research highlights microRNAs (miRNAs) within MSC-released extracellular vesicles that can potentially promote cartilage regeneration and hinder KOA progression. This suggests exosomes (Exos) as a promising avenue for future treatment. While these findings emphasize the need for effective KOA progression management, further safety and efficacy validation for Exos is essential. AIM: To explore miR-29a's role in KOA, we'll create miR-29a-loaded vesicles, testing for early treatment in rat models. METHODS: Extraction of bone marrow MSC-derived extracellular vesicles, preparation of engineered vesicles loaded with miR-29a using ultrasonication, and identification using quantitative reverse transcription polymerase chain reaction; after establishing a rat model of KOA, rats were randomly divided into three groups: Blank control group injected with saline, normal extracellular vesicle group injected with normal extracellular vesicle suspension, and engineered extracellular vesicle group injected with engineered extracellular vesicle suspension. The three groups were subjected to general behavioral observation analysis, imaging evaluation, gross histological observation evaluation, histological detection, and immunohistochemical detection to compare and evaluate the progress of various forms of arthritis. RESULTS: General behavioral observation results showed that the extracellular vesicle group and engineered extracellular vesicle group had better performance in all four indicators of pain, gait, joint mobility, and swelling compared to the blank control group. Additionally, the engineered extracellular vesicle group had better pain relief at 4 wk and better knee joint mobility at 8 wk compared to the normal extracellular vesicle group. Imaging examination results showed that the blank control group had the fastest progression of arthritis, the normal extracellular vesicle group had a relatively slower progression, and the engineered extracellular vesicle group had the slowest progression. Gross histological observation results showed that the blank control group had the most obvious signs of arthritis, the normal extracellular vesicle group showed signs of arthritis, and the engineered extracellular vesicle group showed no significant signs of arthritis. Using the Pelletier gross score evaluation, the engineered extracellular vesicle group had the slowest progression of arthritis. Results from two types of staining showed that the articular cartilage of rats in the normal extracellular vesicle and engineered extracellular vesicle groups was significantly better than that of the blank control group, and the engineered extracellular vesicle group had the best cartilage cell and joint surface condition. Immunohistochemical detection of type II collagen and proteoglycan showed that the extracellular matrix of cartilage cells in the normal extracellular vesicle and engineered extracellular vesicle groups was better than that of the blank control group. Compared to the normal extracellular vesicle group, the engineered extracellular vesicle group had a better regulatory effect on the extracellular matrix of cartilage cells. CONCLUSION: Engineered Exos loaded with miR-29a can exert anti-inflammatory effects and maintain extracellular matrix stability, thereby protecting articular cartilage, and slowing the progression of KOA.

Bone marrow mesenchymal stem cells paracrine TGF-ß1 to mediate the biological activity of osteoblasts in bone repair.

BACKGROUND: Bone marrow mesenchymal stem cells (BMSCs) are an important source of seed cells for regenerative medicine and tissue engineering therapy. BMSCs have multiple differentiation potentials and can release paracrine factors to facilitate tissue repair. Although the role of the osteogenic differentiation of BMSCs has been fully confirmed, the function and mechanism of BMSC paracrine factors in bone repair are still largely unclear. This study aimed to determine the roles of transforming growth factor beta-1 (TGF-ß1) produced by BMSCs in bone tissue repair. METHODS: To confirm our hypothesis, we used a Transwell system to coculture hBMSCs and human osteoblast-like cells without contact, which could not only avoid the interference of the osteogenic differentiation of hBMSCs but also establish the cell-cell relationship between hBMSCs and human osteoblast-like cells and provide stable paracrine substances. In the transwell coculture system, alkaline phosphatase activity, mineralized nodule formation, cell migration and chemotaxis analysis assays were conducted. RESULTS: Osteogenesis, migration and chemotaxis of osteoblast-like cells were regulated by BMSCs in a paracrine manner via the upregulation of osteogenic and migration-associated genes. A TGF-ß receptor I inhibitor (LY3200882) significantly antagonized BMSC-induced biological activity and related gene expression in osteoblast-like cells. Interestingly, coculture with osteoblast-like cells significantly increased the production of TGF-ß1 by BMSCs, and there was potential intercellular communication between BMSCs and osteoblast-like cells. CONCLUSIONS: Our findings provide evidence that the biological mechanism of BMSC-produced TGF-ß1 promotes bone regeneration and repair, providing a theoretical basis and new directions for the application of BMSC transplantation in the treatment of osteonecrosis and bone injury.

Inactivation of Fam20b in the neural crest-derived mesenchyme of mouse causes multiple craniofacial defects.

The glycosaminoglycan (GAG) chains attached to the core proteins of proteoglycans exert multiple roles, such as enriching signal molecules and regulating the binding of ligands to the corresponding receptors. A newly identified kinase - family with sequence similarity 20 member B (FAM20B) - is essential for the formation of GAG chains. The FAM20B protein phosphorylates the initial xylose on the side chain of a serine residue in the protein. Although the GAG chains of proteoglycans are believed to be indispensable during craniofacial development, there are few reports on their exact functions in craniofacial organogenesis. In this study, by mating Wnt1-cre mice with Fam20b-floxed mice (Fam20bflox/flox), we created Wnt1-Cre;Fam20bflox/flox mice in which Fam20b is ablated in the neural crest-derived mesenchyme. The Wnt1-Cre;Fam20bflox/flox mice died immediately after birth because of complete cleft palates. In addition to cleft palate, Wnt1-Cre;Fam20bflox/flox mice also manifested tongue elevation, micrognathia, microcephaly, suture widening, and reduced mineralization in the calvaria, facial bones, and temporomandibular joint. These findings indicate that the proteoglycans formed through the catalysis of FAM20B are essential for the morphogenesis and mineralization of the craniofacial complex.