Metformin acts on miR-181a-5p/PAI-1 axis in stem cells providing new strategies for improving age-related osteogenic differentiation decline.

A general decline in the osteogenic differentiation capacity of human bone marrow mesenchymal stem cells (hBMSCs) in the elderly is a clinical consensus, with diverse opinions on the mechanisms. Many studies have demonstrated that metformin (MF) significantly protects against osteoporosis and reduces fracture risk. However, the exact mechanism of this effect remains unclear. In this study, we found that the decreased miR-181a-5p expression triggered by MF treatment plays a critical role in recovering the osteogenic ability of aging hBMSCs (derived from elderly individuals). Notably, the miR-181a-5p expression in hBMSCs was significantly decreased with prolonged MF (1000 µM) treatment. Further investigation revealed that miR-181a-5p overexpression markedly impairs the osteogenic ability of hBMSCs, while miR-181a-5p inhibition reveals the opposite result. We also found that miR-181a-5p could suppress the protein translation process of plasminogen activator inhibitor-1 (PAI-1), as evidenced by luciferase assays and western blots. Additionally, low PAI-1 levels were associated with diminished osteogenic ability, whereas high levels promoted it. These findings were further validated in human umbilical cord mesenchymal stem cells (hUCMSCs). Finally, our in vivo experiment with a bone defects rat model confirmed that the agomiR-181a-5p (long-lasting miR-181a-5p mimic) undermined bone defects recovery, while the antagomiR-181a-5p (long-lasting miR-181a-5p inhibitor) significantly promoted the bone defects recovery. In conclusion, we found that MF promotes bone tissue regeneration through the miR-181a-5p/PAI-1 axis by affecting MSC osteogenic ability, providing new strategies for the treatment of age-related bone regeneration disorders.

Endothelial progenitor cell derived exosomes mediated miR-182-5p delivery accelerate diabetic wound healing via down-regulating PPARG.

Diabetic wound is one of the most common and serious complications of diabetes, which is characterized by abnormal number and quality of wound repair related cells. Previous studies have shown that human endothelial progenitor cells derived exosomes (EPCs-EXO) can promote diabetic wound healing through modulating vascular endothelial cell function. The purpose of this study was to investigate the biological effects and molecular mechanisms of EPCs-EXO on diabetic wound healing. The regulation of EPCs-EXO on human immortalized epidermal cell line HaCaT in high glucose (HG) environment was evaluated. Our data showed that EPCs-EXO promoted the proliferation, migration, while inhibited apoptosis of HaCaTs challenged by HG via elevating miR-182-5p expression level in vitro. Skin wound healing was significantly enhanced by EPCs-EXO in diabetic mice. Moreover, bioinformatics analyses and luciferase reporter assay indicated that exosomal miR-182-5p was bound to PPARG 3' UTR sequence and inhibited the expression of PPARG. Collectively, our findings provided a new role of EPCs-EXO in the clinical treatment of diabetic skin wounds. Diabetic wound is one of the most common and serious complications of diabetes, which is characterized by abnormal number and quality of wound repair related cells. Previous studies have shown that human endothelial progenitor cells derived exosomes (EPCs-EXO) can promote diabetic wound healing through modulating vascular endothelial cell function. The purpose of this study was to investigate the biological effects and molecular mechanisms of EPCs-EXO on diabetic wound healing. The regulation of EPCs-EXO on human immortalized epidermal cell line HaCaT in high glucose (HG) environment was evaluated. Our data showed that EPCs-EXO promoted the proliferation, migration, while inhibited apoptosis of HaCaTs challenged by HG via elevating miR-182-5p expression level in vitro. Skin wound healing was significantly enhanced by EPCs-EXO in diabetic mice. Moreover, bioinformatics analyses and luciferase reporter assay indicated that exosomal miR-182-5p was bound to PPARG 3' UTR sequence and inhibited the expression of PPARG. Collectively, our findings provided a new role of EPCs-EXO in the clinical treatment of diabetic skin wounds.

DPA promotes hBMSCs osteogenic differentiation by miR-9-5p/ERK/ALP signaling pathway.

Docosahexaenoic acid (DHA) has been reported potentiate osteogenic differentiation, while Docosapentaenoic acid (DPA), another Omega-3 fatty acid, its contribution to the osteogenic differentiation of human bone-marrow-derived mesenchymal stromal cells (hBMSCs) is not entirely elucidated. The Alizarin Red S (ARS) staining and the expression of osteogenesis­associated genes were analyzed during osteogenic induction by DPA. Then, bioinformatics analysis and dual luciferase reporter assays were investigated to confirm the interactions between miR-9-5p and alkaline phosphatase (ALP). miR-9-5p mimics / inhibitor were transfected to human hBMSCs and the osteogenic assay above was also performed. Furthermore, DPA significantly promoted the phosphorylation of ERK via miR-9-5p. PD98059, a highly specific and potent ERK1/2 inhibitor, inhibited the activation of ALP and partially reversed the role of DPA during osteogenic differentiation. These data indicated that DPA promoted osteogenic differentiation of hBMSCs potentially through miR-9-5p/ERK/ALP signaling pathway, providing a potentially useful therapeutic strategy for patients to improve bone loss.

Exosome-like Nanovesicles Derived from the Mucilage of Pinctada Martensii Exhibit Antitumor Activity against 143B Osteosarcoma Cells.

Osteosarcoma is prone to metastasis and has a low long-term survival rate. The drug treatment of osteosarcoma, side effects of treatment drugs, and prognosis of patients with lung metastasis continue to present significant challenges, and the efficacy of drugs used in the treatment of osteosarcoma remains low. The development of new therapeutic drugs is urgently needed. In this study, we successfully isolated Pinctada martensii mucilage exosome-like nanovesicles (PMMENs). Our findings demonstrated that PMMENs inhibited the viability and proliferation of 143B cells, induced apoptosis, and inhibited cell proliferation by suppressing the activation of the ERK1/2 and Wnt signaling pathways. Furthermore, PMMENs inhibited cell migration and invasion by downregulating N-cadherin, vimentin, and matrix metalloprotease-2 protein expression levels. Transcriptomic and metabolomic analyses revealed that differential genes were co-enriched with differential metabolites in cancer signaling pathways. These results suggest that PMMENs may exert anti-tumor activity by targeting the ERK1/2 and Wnt signaling pathways. Moreover, tumor xenograft model experiments showed that PMMENs can inhibit the growth of osteosarcoma in mice. Thus, PMMENs may be a potential anti-osteosarcoma drug.

S100B gene polymorphisms are associated with the S100B level and Alzheimer's disease risk by altering the miRNA binding capacity.

To examine the role of S100B in genetic susceptibility to Alzheimer's disease (AD), we conducted a case-control study to analyze four polymorphism loci (rs2839364, rs1051169, rs2300403, and rs9722) of the S100B gene and AD risk. We found an independent increased risk of AD in ApoE ε4(-) subjects carrying the rs9722 AA-genotype (OR = 2.622, 95% CI = 1.399-4.915, P = 0.003). Further investigation revealed the serum S100B levels to be lower in rs9722 GG carriers than in rs9722 AA carriers (P = 0.003). We identified three miRNAs (miR-340-3p, miR-593-3p, miR-6827-3p) in which the seed match region covered locus rs9722. Luciferase assays indicated that the rs9722 G allele has a higher binding affinity to miR-6827-3p than the rs9722 A allele, leading to a significantly decreased fluorescence intensity. Subsequent western blot analysis showed that the S100B protein level of SH-SY5Y cells, which carry the rs9722 G allele, decreased significantly following miR-6827-3p stimulation (P = 0.009). The present study suggests that the rs9722 polymorphism may upregulate the expression of S100B by altering the miRNA binding capacity and may thus increase the AD risk. This finding would be of great help for the early diagnosis of AD.