Milk-Derived Small Extracellular Vesicles Promote Osteogenic Differentiation and Inhibit Inflammation via microRNA-21.

Chronic apical periodontitis (CAP) is a disease with characteristics of inflammation and bone loss. In this study, our objective was to examine the function of small extracellular vesicles (sEVs) obtained from milk in encouraging osteogenic differentiation and inhibiting inflammation by miR-21 in CAP. The expression of miR-21 was detected using qRT-PCR in human CAP samples. The impact of miR-21 on the process of osteogenic differentiation was investigated using CCK-8, qRT-PCR, immunofluorescence staining, and Western blot analysis. The evaluation of RAW 264.7 cell polarization and the assessment of inflammatory factor expression were conducted through qRT-PCR. The influence of sEVs on MC3T3-E1 cells and RAW 264.7 cells was examined, with a particular emphasis on the involvement of miR-21. In human CAP samples, a decrease in miR-21 expression was observed. MiR-21 increased the expression of osteogenesis-related genes and M2 polarization genes while decreasing the expression of M1 polarization genes and inflammatory cytokines. Treatment with milk-derived sEVs also promoted osteogenesis and M2 polarization while inhibiting M1 polarization and inflammation. Conversely, the addition of miR-21 inhibitors resulted in opposite effects. Our results indicated that sEVs derived from milk had a positive effect on bone formation and activation of anti-inflammatory (M2) macrophages and simultaneously reduced inflammation by regulating miR-21 in CAP.

Milk-derived small extracellular vesicles: nanomaterials to promote bone formation.

Small extracellular vesicles (sEVs) are an important component in the paracrine pathway. They can be used as a substitute for seed cells and have shown good application prospects in promoting bone regeneration. Cow's milk could be used as a source of sEVs with good biocompatibility and cost-effectiveness, with easy availability, low cost and low toxicity. This study focused on the role and mechanism of small extracellular vesicles derived from milk in bone repair. In order to explore the mechanism via which Milk-sEVs promote bone repair, we screened the differential gene GJA1 in Milk-sEV-treated osteoblasts through transcriptome chips, and verified the transcript AP3B1 of GJA1 through chromatin immunoprecipitation (CHIP). We have proved by in vivo and in vitro experiments that milk-derived sEVs (Milk-sEVs) increase the repair ability of bone tissue, and promote expression of the osteogenic gene GJA1 through the transcript AP3B1.

Milk-derived small extracellular vesicles inhibit the MAPK signaling pathway through CD36 in chronic apical periodontitis.

BACKGROUND: Small extracellular vesicles derived from milk (Milk-sEVs) have the advantages of easy availability, low cost, low toxicity, and inhibition of inflammation. CD36 mediates inflammation stress in a variety of disease states. The purpose of this study was to investigate the role of Milk-sEVs in inhibiting fibroblast inflammation through CD36 and provide reference data for the treatment of chronic apical periodontitis. RESULTS: The addition of Milk-sEVs resulted in decreased expression of inflammation-related factors in L929 cells, and transcriptome sequencing screened for the DEG CD36 in the Milk-sEV treatment group under inflammation. The mouse model of apical periodontitis was successfully established, and CD36 expression increased with the development of inflammation. Transfection of si-CD36 into L929 cells reduced inflammation by inhibiting activation of the MAPK signaling pathway. CONCLUSIONS: CD36 expression increased with the development of apical periodontitis. In the setting of LPS-mediated inflammation, Milk-sEVs inhibited activation of the MAPK signaling pathway by decreasing the expression of CD36 in L929 cells and thereby reducing inflammation.

microRNAs delivered by small extracellular vesicles in MSCs as an emerging tool for bone regeneration.

Bone regeneration is a dynamic process that involves angiogenesis and the balance of osteogenesis and osteoclastogenesis. In bone tissue engineering, the transplantation of mesenchymal stem cells (MSCs) is a promising approach to restore bone homeostasis. MSCs, particularly their small extracellular vesicles (sEVs), exert therapeutic effects due to their paracrine capability. Increasing evidence indicates that microRNAs (miRNAs) delivered by sEVs from MSCs (MSCs-sEVs) can alter gene expression in recipient cells and enhance bone regeneration. As an ideal delivery vehicle of miRNAs, MSCs-sEVs combine the high bioavailability and stability of sEVs with osteogenic ability of miRNAs, which can effectively overcome the challenge of low delivery efficiency in miRNA therapy. In this review, we focus on the recent advancements in the use of miRNAs delivered by MSCs-sEVs for bone regeneration and disorders. Additionally, we summarize the changes in miRNA expression in osteogenic-related MSCs-sEVs under different microenvironments.

FBS-Derived Exosomes as a Natural Nano-Scale Carrier for Icariin Promote Osteoblast Proliferation.

Icariin is a class IV drug of low solubility, permeability, and poor bioavailability. Synthetic nanomaterials have developed rapidly. However, some literatures point out that synthetic nanomaterials such as liposomes, aptamers, metal nanoparticles, and nanogels have high toxicity and are affected by the reticuloendothelial system or mononuclear phagocyte system. It is known that exosomes could be used as an ideal clinical drug delivery vehicle to avoid the above-mentioned problems to a certain extent. Studies have shown that drugs can be loaded into exosomes by passive and active loading. We used Fetal bovine serum (FBS) exosomes to carry Icariin for the first time in this experiment, FBS exosomes-Icariin (FBS EXO-ICA) more effectively promoted the proliferation of osteoblasts and bone regeneration than Icariin alone. FBS EXO-ICA could become a new nano scale drug formulation for treating diseases associated with bone loss.