Mesenchymal stem cell-conditioned medium alleviates high fat-induced hyperglucagonemia via miR-181a-5p and its target PTEN/AKT signaling

Cardioprotection of voluntary exercise against breast cancer-induced cardiac injury via STAT3

Exercise is an effective way to alleviate breast cancer-induced cardiac injury to a certain extent. However, whether voluntary exercise (VE) activates cardiac signal transducer and activator of transcription 3 (STAT3) and the underlying mechanisms remain unclear. This study investigated the role of STAT3-microRNA(miRNA)-targeted protein axis in VE against breast cancer-induced cardiac injury.VE for 4 weeks not only improved cardiac function of transgenic breast cancer female mice [mouse mammary tumor virus-polyomavirus middle T antigen (MMTV-PyMT +)] compared with littermate mice with no cancer (MMTV-PyMT -), but also increased myocardial STAT3 tyrosine 705 phosphorylation. Significantly more obvious cardiac fibrosis, smaller cardiomyocyte size, lower cell viability, and higher serum tumor necrosis factor (TNF)-α were shown in MMTV-PyMT + mice compared with MMTV-PyMT - mice, which were ameliorated by VE. However, VE did not influence the tumor growth. MiRNA sequencing identified that miR-181a-5p was upregulated and miR-130b-3p was downregulated in VE induced-cardioprotection. Myocardial injection of Adeno-associated virus serotype 9 driving STAT3 tyrosine 705 mutations abolished cardioprotective effects above. Myocardial STAT3 was identified as the transcription factor binding the promoters of pri-miR-181a (the precursor of miR-181a-5p) and HOX transcript antisense RNA (HOTAIR, sponged miR-130b-3p) in isolated cardiomyocytes. Furthermore, miR-181a-5p targeting PTEN and miR-130b-3p targeting Zinc finger and BTB domain containing protein 20 (Zbtb20) were proved in AC-16 cells. These findings indicated that VE protects against breast cancer-induced cardiac injury via activating STAT3 to promote miR-181a-5p targeting PTEN and to promote HOTAIR to sponge miR-130b-3p targeting Zbtb20, helping to develop new targets in exercise therapy for breast cancer-induced cardiac injury.

Mesenchymal stromal cells ameliorate mitochondrial dysfunction in α cells and hyperglucagonemia in type 2 diabetes via SIRT1/FoxO3a signaling

Dysregulation of α cells results in hyperglycemia and hyperglucagonemia in type 2 diabetes mellitus (T2DM). Mesenchymal stromal cell (MSC)-based therapy increases oxygen consumption of islets and enhances insulin secretion. However, the underlying mechanism for the protective role of MSCs in α-cell mitochondrial dysfunction remains unclear. Here, human umbilical cord MSCs (hucMSCs) were used to treat 2 kinds of T2DM mice and αTC1-6 cells to explore the role of hucMSCs in improving α-cell mitochondrial dysfunction and hyperglucagonemia. Plasma and supernatant glucagon were detected by enzyme-linked immunosorbent assay (ELISA). Mitochondrial function of α cells was assessed by the Seahorse Analyzer. To investigate the underlying mechanisms, Sirtuin 1 (SIRT1), Forkhead box O3a (FoxO3a), glucose transporter type1 (GLUT1), and glucokinase (GCK) were assessed by Western blotting analysis. In vivo, hucMSC infusion improved glucose and insulin tolerance, as well as hyperglycemia and hyperglucagonemia in T2DM mice. Meanwhile, hucMSC intervention rescued the islet structure and decreased α- to β-cell ratio. Glucagon secretion from αTC1-6 cells was consistently inhibited by hucMSCs in vitro. Meanwhile, hucMSC treatment activated intracellular SIRT1/FoxO3a signaling, promoted glucose uptake and activation, alleviated mitochondrial dysfunction, and enhanced ATP production. However, transfection of SIRT1 small interfering RNA (siRNA) or the application of SIRT1 inhibitor EX-527 weakened the therapeutic effects of hucMSCs on mitochondrial function and glucagon secretion. Our observations indicate that hucMSCs mitigate mitochondrial dysfunction and glucagon hypersecretion of α cells in T2DM via SIRT1/FoxO3a signaling, which provides novel evidence demonstrating the potential for hucMSCs in treating T2DM.

Adipose-derived miRNAs as potential biomarkers for predicting adulthood obesity and its complications: A systematic review and bioinformatic analysis

Adipose tissue is the first and primary target organ of obesity and the main source of circulating miRNAs in patients with obesity. This systematic review aimed to analyze and summarize the generation and mechanisms of adipose-derived miRNAs and their role as early predictors of various obesity-related complications. Literature searches in the PubMed and Web of Science databases using terms related to miRNAs, obesity, and adipose tissue. Pre-miRNAs from the Human MicroRNA Disease Database, known to regulate obesity-related metabolic disorders, were combined for intersection processing. Validated miRNA targets were sorted through literature review, and enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes via the KOBAS online tool, disease analysis, and miRNA transcription factor prediction using the TransmiR v. 2.0 database were also performed. Thirty miRNAs were identified using both obesity and adipose secretion as criteria. Seventy-nine functionally validated targets associated with 30 comorbidities of these miRNAs were identified, implicating pathways such as autophagy, p53 pathways, and inflammation. The miRNA precursors were analyzed to predict their transcription factors and explore their biosynthesis mechanisms. Our findings offer potential insights into the epigenetic changes related to adipose-driven obesity-related comorbidities.

Activation of the Wnt/β-catenin signalling pathway enhances exosome production by hucMSCs and improves their capability to promote diabetic wound healing

BACKGROUND

The use of stem cell-derived exosomes (Exos) as therapeutic vehicles is receiving increasing attention. Exosome administration has several advantages over cell transplantation, thus making exosomes promising candidates for large-scale clinical implementation and commercialization. However, exosome extraction and purification efficiencies are relatively low, and therapeutic heterogeneity is high due to differences in culture conditions and cell viability. Therefore, in this study, we investigated a priming procedure to enhance the production and therapeutic effects of exosomes from human umbilical cord mesenchymal stem cells (hucMSCs). After preconditioning hucMSCs with agonists/inhibitors that target the Wnt/β-catenin pathway, we assessed both the production of exosomes and the therapeutic efficacy of the optimized exosomes in the context of diabetic wound healing, hoping to provide a safer, more stable and more effective option for clinical application.

RESULTS

The Wnt signalling pathway agonist CHIR99021 increased exosome production by 1.5-fold without causing obvious changes in the characteristics of the hucMSCs or the size of the exosome particles. Further studies showed that CHIR99021 promoted the production of exosomes by facilitating exocytosis. This process was partly mediated by SNAP25. To further explore whether CHIR99021 changed the cargo that was loaded into the exosomes and its therapeutic effects, we performed proteomic and transcriptomic analyses of exosomes from primed and control hucMSCs. The results showed that CHIR99021 significantly upregulated the expression of proteins that are associated with cell migration and wound healing. Animal experiments confirmed that, compared to control hucMSC-derived exosomes, CHIR99021-pretreated hucMSC-derived exosomes (CHIR-Exos) significantly accelerated wound healing in diabetic mice, enhanced local collagen deposition, promoted angiogenesis, and reduced chronic inflammation. Subsequent in vitro experiments confirmed that the CHIR-Exos promoted wound healing by facilitating cell migration, inhibiting oxidative stress-induced apoptosis, and preventing cell cycle arrest.

CONCLUSIONS

The Wnt agonist CHIR99021 significantly increased exosome secretion by hucMSCs, which was partly mediated by SNAP25. Notably, CHIR99021 treatment also significantly increased the exosomal levels of proteins that are associated with wound healing and cell migration, resulting in enhanced acceleration of wound healing. All of these results suggested that pretreatment of hucMSCs with CHIR99021 not only promoted exosome production but also improved the exosome therapeutic efficacy, thus providing a promising option for large-scale clinical implementation and commercialization.

Therapeutic Potential of Mesenchymal Stem Cell‐Derived Conditioned Medium for Diabetes Mellitus and Related Complications

Diabetes mellitus (DM) is one of the most life‐threatening metabolic disorders, with 9% of the global prevalence, and it is estimated to be rising to 12.2% in 2045. Currently, there is no definitive treatment for DM. Although life‐saving, insulin administration to control blood sugar is not a cure for DM and is insufficient to prevent DM‐related complications such as nephropathy, neuropathy, or retinopathy. For this reason, studies are continuing to develop treatments that will provide β‐cell regeneration while suppressing autoimmunity. Mesenchymal stem cells (MSCs) are multipotent stem cells with a high proliferation capacity, immunosuppression, and immunomodulation ability. MSCs have gained therapeutic importance with these properties besides their differentiation ability. The immunosuppressive and immunomodulatory properties of the cells arise from the soluble and insoluble factors they secrete into the extracellular environment. Therefore, the culture medium where these cells grow has therapeutic value and is named conditioned medium (CM). In this context, CM obtained from MSCs can provide a similar therapeutic effect with fewer safety concerns. Furthermore, preconditioning of MSCs can improve the effectiveness of these cells and associated cellular products. So, this review summarizes the recent advances in MSC‐derived CMs and their therapeutic potential for DM and related complications.

miR-181a targets PTEN to mediate the neuronal injury caused by oxygen-glucose deprivation and reoxygenation

Evidence suggests that the microRNA-181 (miR-181) family performs various roles in the pathophysiology of cerebral ischemia and reperfusion injury (CIRI). MiR-181a has been identified as a critical determinant of neuronal survival. Moreover, the significance of miR-181a in controlling neuronal death after CIRI has received little attention. The objective of this study was to assess the role of miR-181a in neuronal cell injury after CIRI. To mimic the in-vitro and in-vivo CIRI, we developed an oxygen-glucose deficiency/reoxygenation (OGD/R) model in SH-SY5Y cells and a transient middle cerebral artery occlusion model in rats. MiR-181a expression was significantly higher in both in-vivo and in-vitro CIRI models. The overexpression of miR-181a increased cell damage and oxidative stress caused by OGD/R, whereas inhibition of miR-181a reduced both. PTEN has also been found to be a direct miR-181a target. PTEN overexpression reduced cell apoptosis and oxidative stress induced by miR-181a upregulation under an OGD/R condition. Furthermore, we found that the rs322931 A allele was related to increased miR-181a levels in IS peripheral blood and higher susceptibility to IS. The current results offer new insights into the understanding of the molecular pathophysiology of CIRI, as well as possible new treatment candidates.

Advances in the applications of mesenchymal stem cell-conditioned medium in ocular diseases

Mesenchymal stem cell-conditioned medium (MSC-CM), also known as secretome, is secreted by MSC and contains a variety of bioactive factors with anti-inflammatory, anti-apoptotic, neuroprotection, and proliferation effects. Increasing evidence proved that MSC-CM plays an important role in various diseases, including skin, bone, muscle, and dental diseases. However, the role of MSC-CM in ocular diseases is not quite clear, Therefore, this article reviewed the composition, biological functions, preparation, and characterization of MSC-CM and summarized current research advances in different sources of MSC-CM in corneal and retinal diseases, including dry eye, corneal epithelial damage, chemical corneal injury, retinitis pigmentosa (RP), anterior ischemic optic neuropathy (AION), diabetic retinopathy (DR), and other retinal degenerative changes. For these diseases, MSC-CM can promote cell proliferation, reduce inflammation and vascular leakage, inhibit retinal cell degeneration and apoptosis, protect corneal and retinal structures, and further improves visual function. Hence, we summarize the production, composition and biological functions of MSC-CM and focus on describing its mechanisms in the treatment of ocular diseases. Furthermore, we look at the unexplored mechanisms and further research directions for MSC-CM based therapy in ocular diseases.

Mesenchymal stromal cells ameliorate diabetes-induced muscle atrophy through exosomes by enhancing AMPK/ULK1-mediated autophagy

BACKGROUND

Diabetes and obesity are associated with muscle atrophy that reduces life quality and lacks effective treatment. Mesenchymal stromal cell (MSC)-based therapy can ameliorate high fat-diet (HFD) and immobilization (IM)-induced muscle atrophy in mice. However, the effect of MSCs on muscle atrophy in type 2 diabetes mellitus (T2DM) and the potential mechanism is unclear. Here, we evaluated the efficacy and explored molecular mechanisms of human umbilical cord MSCs (hucMSCs) and hucMSC-derived exosomes (MSC-EXO) on diabetes- and obesity-induced muscle atrophy.

METHODS

Diabetic db/db mice, mice fed with high-fat diet (HFD), mice with hindlimb immobilization (IM), and C2C12 myotubes were used to explore the effect of hucMSCs or MSC-EXO in alleviating muscle atrophy. Grip strength test and treadmill running were used to measure skeletal muscle strength and performance. Body composition, muscle weight, and muscle fibre cross-sectional area (CSA) was used to evaluate muscle mass. RNA-seq analysis of tibialis anterior (TA) muscle and Western blot analysis of muscle atrophy signalling, including MuRF1 and Atrogin 1, were performed to investigate the underlying mechanisms.

RESULTS

hucMSCs increased grip strength (P = 0.0256 in db/db mice, P = 0.012 in HFD mice, P = 0.0097 in IM mice), running endurance (P = 0.0154 in HFD mice, P = 0.0006 in IM mice), and muscle mass (P = 0.0004 in db/db mice, P = 0.0076 in HFD mice, P = 0.0144 in IM mice) in all models tested, with elevated CSA of muscle fibres (P < 0.0001 in db/db mice and HFD mice, P = 0.0088 in IM mice) and reduced Atrogin1 (P = 0.0459 in db/db mice, P = 0.0088 in HFD mice, P = 0.0016 in IM mice) and MuRF1 expression (P = 0.0004 in db/db mice, P = 0.0077 in HFD mice, P = 0.0451 in IM mice). MSC-EXO replicated all these hucMSC-mediated changes (P = 0.0103 for grip strength, P = 0.013 for muscle mass, P < 0.0001 for CSA of muscle fibres, P = 0.0171 for Atrogin1 expression, and P = 0.006 for MuRF1 expression). RNA-seq revealed that hucMSCs activated the AMPK/ULK1 signalling and enhanced autophagy. Knockdown of AMPK or inhibition of autophagy with 3-methyladenine (3-MA) diminished the beneficial anti-atrophy effects of hucMSCs or MSC-EXO.

CONCLUSIONS

Our results suggest that human umbilical cord mesenchymal stromal cells mitigate diabetes- and obesity-induced muscle atrophy via enhancing AMPK/ULK1-mediated autophagy through exosomes, with implications of applying hucMSCs or hucMSC-derived exosomes to treat muscle atrophy.

MALAT1 regulates hypertrophy of cardiomyocytes by modulating the miR-181a/HMGB2 pathway

Noncoding RNAs are important for regulation of cardiac hypertrophy. The function of MALAT1 (a long noncoding mRNA), miR-181a, and HMGB2; their contribution to cardiac hypertrophy; and the regulatory relationship between them during this process remain unknown. In the present study, we treated primary cardiomyocytes with angiotensin II (Ang II) to mimic cardiac hypertrophy. MALAT1 expression was significantly downregulated in Ang II-treated cardiomyocytes compared with control cardiomyocytes. Ang II-induced cardiac hypertrophy was suppressed by overexpression of MALAT1 and promoted by genetic knockdown of MALAT1. A dual-luciferase reporter assay demonstrated that MALAT1 acted as a sponge for miR-181a and inhibited its expression during cardiac hypertrophy. Cardiac hypertrophy was suppressed by overexpression of a miR-181a inhibitor and enhanced by overexpression of a miR-181a mimic. HMGB2 was downregulated during cardiac hypertrophy and was identified as a target of miR-181a by bioinformatics analysis and a dual-luciferase reporter assay. miR-181a overexpression decreased the mRNA and protein levels of HMGB2. Rescue experiments indicated that MALAT1 overexpression reversed the effect of miR-181a on HMGB2 expression. In summary, the results of the present study show that MALAT1 acts as a sponge for miR-181a and thereby regulates expression of HMGB2 and development of cardiac hypertrophy. The novel MALAT1/miR-181a/HMGB2 axis might play a crucial role in cardiac hypertrophy and serve as a new therapeutic target.

Circ_0058792 regulates osteogenic differentiation through miR-181a-5p/Smad7 axis in steroid-induced osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) caused by steroids is a severe orthopedic disorder resulting from the use of high-dose steroid drugs, characterized by structural changes in the bone, joint dysfunction, and femoral head collapse. CircRNAs and miRNAs have increasingly been suggested to play pivotal roles in osteogenic differentiation and osteogenesis. Significant upregulation of circ_0058792 was observed in patients with steroid-induced ONFH. Bioinformatic analysis showed that circ_0058792 might act as a sponge for miR-181a-5p. This study further investigated the mechanisms underlying the role of circ_0058792 and miR-181a-5p in osteogenic differentiation in methylprednisolone-induced ONFH rats and MC3T3-E1 cells. The results showed a notable decrease in the serum of miR-181a-5p in methylprednisolone-induced ONFH rats. Silencing of circ_0058792 using siRNAs and overexpression of miR-181a-5p significantly increased alkaline phosphatase activity and matrix mineralization capacity. Additionally, markers for osteogenic differentiation were significantly upregulated in miR-181a-5p-transfected cells. However, overexpression of circ_0058792 and the addition of the miR-181a-5p inhibitor reversed this increase. Smad7 was identified to be miR-181a-5p's direct target and circ_0058792 was confirmed to be miR-181a-5p's competing endogenous RNA (ceRNA). Upregulation of miR-181a-5p promotes phosphorylation of Smad2 and Smad3. Furthermore, circ_0058792 and miR-181a-5p had opposing effects on Smad7 expression. Collectively, these findings indicate that circ_0058792 regulates osteogenic differentiation by sponging miR-181a-5p via the TGF-β/Smad7 pathway. These findings elucidated the functions of circ_0058792 and miR-181a-5p in the regulation of steroid-induced ONFH. Our findings also indicated that circ_0058792 and miR-181a-5p are possible diagnostic markers and therapeutic targets for treating steroid-induced ONFH.