MiRNA-486 regulates angiogenic activity and survival of mesenchymal stem cells under hypoxia through modulating Akt signal

Exosomal miR-486 derived from bone marrow mesenchymal stem cells promotes angiogenesis following cerebral ischemic injury by regulating the PTEN/Akt pathway

Bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) have been shown to promote angiogenesis after ischemic stroke, in which microRNAs (miRs) are believed to play an important role in exosome-mediated therapeutic effects, though the mechanism is still not clear. In this study, a series of molecular biological and cellular assays, both in vitro and in vivo, were performed to elucidate the role of exosomal miR-486 in angiogenesis following cerebral ischemic and its molecular mechanisms. Our results revealed that BMSC-Exos significantly improved neurological function and increased microvessel density in ischemic stroke rats. In vitro assays showed that BMSC-Exos promoted the proliferation, migration, and tube formation ability of oxygen-glucose deprivation/reoxygenation (OGD/R) injured rat brain microvascular endothelial cells (RBMECs). Importantly, BMSC-Exos increased the expression of miR-486 and phosphorylated protein kinase B (p-Akt) and down-regulated the protein level of phosphatase and tensin homolog (PTEN) in vivo and in vitro. Mechanistic studies demonstrated that transfection with miR-486 mimic enhanced RBMECs angiogenesis and increased p-Akt expression, while inhibited PTEN expression. On the other hand, the miR-486 inhibitor induced an opposite effect, which could be blocked by PTEN siRNA. It was thus concluded that exosomal miR-486 from BMSCs may enhance the functional recovery by promoting angiogenesis following cerebral ischemic injury, which might be related to its regulation of the PTEN/Akt pathway.

Active ingredients Isorhamnetin of Croci Srigma inhibit stomach adenocarcinomas progression by MAPK/mTOR signaling pathway

Gastric cancer (GC) remains the third leading cause of cancer-related mortality in the world, and ninety-five percent of GC are stomach adenocarcinomas (STAD). The active ingredients of Croci Stigma, such as Isorhamnetin, Crocin, Crocetin and Kaempferol, all have antitumor activity. However, their chemical and pharmacological profiles remain to be elusive. In this study, network pharmacology was used to characterize the action mechanism of Croci Stigma. All compounds were obtained from the traditional Chinese medicine systems pharmacology (TCMSP) database, and active ingredients were selected by their oral bioavailability and drug-likeness index. The targets of Croci Stigma active ingredients were obtained from the traditional Chinese medicine integrated database (TCMID), whereas the related genes of STAD were obtained from DisGeNET platform. Cytoscape was used to undertake visual analyses of the Drug Ingredients-Gene Symbols-Disease (I-G-D) network, and 2 core genes including MAPK14, ERBB3 were obtained, which are the predicted targets of isorhamnetin (IH) and quercetin, respectively. Data analysis from TCGA platform showed that MAPK14 and ERBB3 all upregulated in STAD patients, but only the effect of MAPK14 expression on STAD patients' survival was significant. Molecular docking showed that IH might affect the function of MAPK14 protein, and then the underlying action mechanisms of IH on STAD were experimentally validated using human gastric cancer cell line, HGC-27 cells. The results showed that IH can inhibit cell proliferation, migration, clonal formation, and arrest cell cycle, but promote the apoptosis of HGC-27 cells. qRT-PCR data demonstrated that IH downregulated the MAPK14 mRNA expression and EMT related genes. WB results showed that IH regulates MAPK/mTOR signaling pathway. These findings suggest that IH has the therapeutic potential for the treatment of STAD.

Role of hypoxia on microRNA-dependant regulation of HGFA - HGF - c-Met signalling pathway in human progenitor and mature endothelial cells

Hepatocyte growth factor (HGF) is considered to be one of the key pro-angiogenic cytokines that stimulates endothelial cells to proliferate and migrate. The activation of the precursor form of HGF is primarily undertaken by the serine protease HGFA. Research indicates that HIF-1α hypoxia stimulates the expression of HGFA, which is synthesized by a range of cells including fibroblasts, endothelium, and macrophages. To date, little is known about the potential role of epigenetic factors in the regulation of the HGFA - HGF - c-Met signalling pathway. The literature suggests that there are several microRNAs (miRNAs, miRs) directly affecting the expression of c-Met under normoxic conditions. The main objective of the research described was to explore the effect of chemically-induced hypoxia on the expression of miRNA molecules in human progenitor and mature endothelial cells, with particulate attention paid to those miRNAs that may specifically affect the HGFA - HGF - c-Met signalling pathway. This publication sheds new light on the role of miRNAs in hypoxia, as well as identifying several miRNAs directly involved in the regulation of HGFA, HGF and c-Met expression in hypoxic conditions. The results indicate that hsa-miR-335-5p, hsa-miR-425-5p and hsa-miR-101-3p are the major miRNAs that appear to play an important role in the regulation of the HGFA - HGF - c-Met signalling pathway.

Microrna-486-5P Regulates Human Pulmonary Artery Smooth Muscle Cell Migration via Endothelin-1

Pulmonary arterial hypertension (PAH) is a fatal or life-threatening disorder characterized by elevated pulmonary arterial pressure and pulmonary vascular resistance. Abnormal vascular remodeling, including the proliferation and phenotypic modulation of pulmonary artery smooth muscle cells (PASMCs), represents the most critical pathological change during PAH development. Previous studies showed that miR-486 could reduce apoptosis in different cells; however, the role of miR-486 in PAH development or HPASMC proliferation and migration remains unclear. After 6 h of hypoxia treatment, miR-486-5p was significantly upregulated in HPASMCs. We found that miR-486-5p could upregulate the expression and secretion of ET-1. Furthermore, transfection with a miR-486-5p mimic could induce HPASMC proliferation and migration. We also found that miRNA-486-5p could downregulate the expression of SMAD2 and the phosphorylation of SMAD3. According to previous studies, the loss of SMAD3 may play an important role in miRNA-486-5p-induced HPASMC proliferation. Although the role of miRNA-486-5p in PAH in in vivo models still requires further investigation and confirmation, our findings show the potential roles and effects of miR-486-5p during PAH development.

Islet-1 Mesenchymal Stem Cells-Derived Exosome-Incorporated Angiogenin-1 Hydrogel for Enhanced Acute Myocardial Infarction Therapy

Although stem cell-derived exosomes have been recognized as new candidates for cell-free treatment in myocardial infarction (MI), the challenge to improve the exosome retention in ischemic tissue remains. Our previous research indicated that islet-1(ISL1) overexpression enhances the paracrine function of mesenchymal stem cells (MSCs) and promotes angiogenesis in a model of MI. In this study, genetically engineered ISL1-MSC-derived exosomes (ISL1-MSCs-Exo) were collected, and the contents were analyzed by exosomal RNA sequencing. Next, we investigated if ISL1-MSCs-Exo could exert therapeutic effects and their incorporation into a new angiogenin-1 hydrogel (Ang-1 gel) could boost the retention of exosomes and further enhance their protective effects. Our results demonstrated that ISL1-MSCs-Exo could play a therapeutic role in vitro and in vivo, which might be due to changed exosomal contents. Ang-1 gel increased the retention and enhanced the anti-apoptosis, proliferation, and angiogenic capacity of ISL1-MSCs-Exo in endothelial cells. Echocardiography revealed that Ang-1 gel significantly augment the therapeutic effects of ISL1-MSCs-Exo for MI. The main mechanism might result from increased retention of ISL1-MSCs-Exo, herein enhanced pro-angiogenetic effects in an ischemic heart. Taken together, our findings indicated that ISL1-MSCs-Exo had endothelium-protective and pro-angiogenic abilities alone and Ang-1 gel could notably retain ISL1-MSCs-Exo at ischemic sites, which improved the survival and angiogenesis of endothelial cells and accelerated the recovery of MI. These results not only shed light on the therapeutic mechanism of ISL1-MSCs-Exo incorporated with Ang-1 gel but also offer a promising therapeutic option for ischemic disease.

miRNA-486-5p: signaling targets and role in non-malignant disease

MicroRNAs (miRNAs) are short non-coding RNAs, highly conserved between species, that are powerful regulators of gene expression. Aberrant expression of miRNAs alters biological processes and pathways linked to human disease. miR-486-5p is a muscle-enriched miRNA localized to the cytoplasm and nucleus, and is highly abundant in human plasma and enriched in small extracellular vesicles. Studies of malignant and non-malignant diseases, including kidney diseases, have found correlations with circulating miR-486-5p levels, supporting its role as a potential biomarker. Pre-clinical studies of non-malignant diseases have identified miR-486-5p targets that regulate major signaling pathways involved in cellular proliferation, migration, angiogenesis, and apoptosis. Validated miR-486-5p targets include phosphatase and tensin homolog (PTEN) and FoXO1, whose suppression activates phosphatidyl inositol-3-kinase (PI3K)/Akt signaling. Targeting of Smad1/2/4 and IGF-1 by miR-486-5p inhibits transforming growth factor (TGF)-β and insulin-like growth factor-1 (IGF-1) signaling, respectively. Other miR-486-5p targets include matrix metalloproteinase-19 (MMP-19), Sp5, histone acetyltransferase 1 (HAT1), and nuclear factor of activated T cells-5 (NFAT5). In this review, we examine the biogenesis, regulation, validated gene targets and biological effects of miR-486-5p in non-malignant diseases.

Impact of High-Altitude Hypoxia on Bone Defect Repair: A Review of Molecular Mechanisms and Therapeutic Implications

Reaching areas at altitudes over 2,500–3,000 m above sea level has become increasingly common due to commerce, military deployment, tourism, and entertainment. The high-altitude environment exerts systemic effects on humans that represent a series of compensatory reactions and affects the activity of bone cells. Cellular structures closely related to oxygen-sensing produce corresponding functional changes, resulting in decreased tissue vascularization, declined repair ability of bone defects, and longer healing time. This review focuses on the impact of high-altitude hypoxia on bone defect repair and discusses the possible mechanisms related to ion channels, reactive oxygen species production, mitochondrial function, autophagy, and epigenetics. Based on the key pathogenic mechanisms, potential therapeutic strategies have also been suggested. This review contributes novel insights into the mechanisms of abnormal bone defect repair in hypoxic environments, along with therapeutic applications. We aim to provide a foundation for future targeted, personalized, and precise bone regeneration therapies according to the adaptation of patients to high altitudes.

Different expression of circulating microRNA profile and plasma SP-D in Tibetan COPD patients

COPD is the fourth leading cause of mortality, and is predicted to be the third leading cause of death worldwide by 2020. But few studies on Tibetan COPD of China. This study identifies distinctive miRNA signatures in Tibetan COPD patients from Tibetan healthy subjects that could serve as diagnostic biomarkers or describe differential molecular mechanisms with potential therapeutic implications. In this study, a total of 210 differentially expressed miRNAs were screened. Analysis of the functions of target genes of differentially expressed miRNAs via GO enrichment analysis revealed that they mainly influenced guanyl-nucleotide exchange factor activity, cell morphogenesis and the positive regulation of GTPase activity. KEGG pathway enrichment analysis showed that these target genes were mainly enriched in signaling by NGF, Axon guidance, developmental biology, ubiquitin mediated proteolysis, and PDGF signaling pathways. MiR-106-5p and miR-486-5p expression was validated in the complete cohort. Age, plasma miR-106-5p, miR-486-5p, SP-D protein levels, and SP-D mRNA level were also determined to be correlated with FEV1%Pred, and may as the risk factors of Tibetan COPD. The combination of plasma miR-106-5p, miR-486-5p and SP-D mRNA expression may be the best model to assist the diagnosis of Tibetan COPD.

Extracellular vesicles derived from lipoaspirate fluid promote fat graft survival

Extracellular vesicles (EVs) are specific subcellular vesicles released by cells under various environmental conditions. Tumescent liposuction is a commonly used procedure in plastic surgery practice. In the present study, we aimed to extract EVs derived from lipoaspirate fluid (LF-EVs) and characterize them using transmission electron microscopy, nanoparticle tracking analysis, and western blotting. The global profiles of proteins and microRNAs from LF-EVs were identified, strongly suggesting a potential regulatory function of LF-EVs. In addition, we investigated the effects and mechanisms of LF-EVs on fat graft survival. Cell functional tests showed that LF-EVs promoted the proliferation, migration, and tube structure formation of human umbilical vein endothelial cells. LF-EVs also promoted the adipogenic differentiation of adipose tissue-derived stem cells. The results of animal experiments showed that the average weights of fat grafts in the LF-EVs-treated group were significantly higher than those in the control group. Histologically, there was less fibrosis, fewer cysts, and increased fat tissue survival in the LF-EVs group. Further investigations of angiogenic and adipogenic factors revealed that LF-EVs also promoted angiogenesis and exerted a pro-adipogenic effect in vivo. Our findings will help to elucidate the functions of LF-EVs and provide a reference dataset for future translational studies.

Melatonin restores osteoporosis-impaired osteogenic potential of bone marrow mesenchymal stem cells and alleviates bone loss through the HGF/PTEN/Wnt/β-catenin axis

Background:

Previous studies reported that melatonin exerts its effect on mesenchymal stem cell (MSC) survival and differentiation into osteogenic and adipogenic lineage. In the current study we aimed to explore the effect of melatonin on osteoporosis and relevant mechanisms.

Methods:

Real-time qualitative polymerase chain reaction (RT-qPCR) and Western blot analysis were conducted to determine expression of HGF, PTEN, and osteoblast differentiation-related genes in ovariectomy (OVX)-induced osteoporosis mice and the isolated bone marrow MSCs (BMSCs). Pre-conditioning with melatonin (1 μmol/l, 10 μmol/l and 100 μmol/l) was carried out in OVX mice BMSCs. Bone microstructure was analyzed using micro-computed tomography and the contents of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase 5b (TRAP5b) were detected by enzyme-linked immunosorbent assay in serum. BMSC proliferation was measured by cell-counting kit (CCK)-8 assay. Alizarin red S (ARS) staining and ALP activity assay were performed to assess BMSC mineralization and calcification. The activity of the Wnt/β-catenin pathway was evaluated by dual-luciferase reporter assay.

Results:

Melatonin prevented bone loss in OVX mice. Melatonin increased ALP expression and reduced TRAP5b expression. HGF and β-catenin were downregulated, while PTEN was upregulated in the femur of OVX mice. Melatonin elevated HGF expression and then stimulated BMSC proliferation and osteogenic differentiation. Additionally, HGF diminished the expression of PTEN, resulting in activated Wnt/β-catenin pathway both in vitro and in vivo. Furthermore, melatonin was shown to ameliorate osteoporosis in OVX mice via the HGF/PTEN/Wnt/β-catenin axis.

Conclusion:

Melatonin could potentially enhance osteogenic differentiation of BMSCs and retard bone loss through the HGF/PTEN/Wnt/β-catenin axis.

Small extracellular vesicles containing miR-486-5p promote angiogenesis after myocardial infarction in mice and nonhuman primates

Stem cell-derived small extracellular vesicles (sEVs) promote angiogenesis after myocardial infarction (MI). However, the components of sEVs that contribute to these effects and the safety and efficiency of engineered sEV treatment for MI remain unresolved. Here, we observed improved cardiac function, enhanced vascular density, and smaller infarct size in mice treated with the sEVs from hypoxia-preconditioned (HP) mesenchymal stem cells (MSCs) (HP-sEVs) than in mice treated with normoxia-preconditioned (N) MSCs (N-sEVs). MicroRNA profiling revealed a higher abundance of miR-486-5p in HP-sEVs than in N-sEVs, and miR-486-5p inactivation abolished the benefit of HP-sEV treatment, whereas miR-486-5p up-regulation enhanced the benefit of N-sEV treatment. Matrix metalloproteinase 19 (MMP19) abundance was lower in HP-sEV-treated than N-sEV-treated mouse hearts but was enriched in cardiac fibroblasts (CFs), and Mmp19 was identified as one of the target genes of miR-486-5p. Conditioned medium from CFs that overexpressed miR-486-5p or silenced MMP19 increased the angiogenic activity of endothelial cells; however, medium from CFs that simultaneously overexpressed Mmp19 and miR-486-5p abolished this effect. Mmp19 silencing in CFs reduced the cleavage of extracellular vascular endothelial growth factor (VEGF). Furthermore, miR-486-5p-overexpressing N-sEV treatment promoted angiogenesis and cardiac recovery without increasing arrhythmia complications in a nonhuman primate (NHP) MI model. Collectively, this study highlights the key role of sEV miR-486-5p in promoting cardiac angiogenesis via fibroblastic MMP19-VEGFA cleavage signaling. Delivery of miR-486-5p-engineered sEVs safely enhanced angiogenesis and cardiac function in an NHP MI model and may promote cardiac repair.

Inflammation-induced inhibition of chaperone-mediated autophagy maintains the immunosuppressive function of murine mesenchymal stromal cells

Macroautophagy has been implicated in modulating the therapeutic function of mesenchymal stromal cells (MSCs). However, the biological function of chaperone-mediated autophagy (CMA) in MSCs remains elusive. Here, we found that CMA was inhibited in MSCs in response to the proinflammatory cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α). In addition, suppression of CMA by knocking down the CMA-related lysosomal receptor lysosomal-associated membrane protein 2 (LAMP-2A) in MSCs significantly enhanced the immunosuppressive effect of MSCs on T cell proliferation, and as expected, LAMP-2A overexpression in MSCs exerted the opposite effect on T cell proliferation. This effect of CMA on the immunosuppressive function of MSCs was attributed to its negative regulation of the expression of chemokine C-X-C motif ligand 10 (CXCL10), which recruits inflammatory cells, especially T cells, to MSCs, and inducible nitric oxide synthase (iNOS), which leads to the subsequent inhibition of T cell proliferation via nitric oxide (NO). Mechanistically, CMA inhibition dramatically promoted IFN-γ plus TNF-α-induced activation of NF-κB and STAT1, leading to the enhanced expression of CXCL10 and iNOS in MSCs. Furthermore, we found that IFN-γ plus TNF-α-induced AKT activation contributed to CMA inhibition in MSCs. More interestingly, CMA-deficient MSCs exhibited improved therapeutic efficacy in inflammatory liver injury. Taken together, our findings established CMA inhibition as a critical contributor to the immunosuppressive function of MSCs induced by inflammatory cytokines and highlighted a previously unknown function of CMA.

Circular RNA expression profiles in the plasma of patients with infantile hemangioma determined using microarray analysis

Circular RNAs (circRNAs) are noncoding RNAs that have important roles in tumor progression. Previous studies have examined the circRNAs involved in infantile hemangioma (IH) tumors. The present study compared the circRNA levels in plasma samples from patients with IH and control individuals. The circRNA expression profiles were determined using microarray in three pairs of plasma samples from patients with proliferative IH and healthy control subjects. Expression of the identified differentially expressed circRNAs was verified using reverse transcription-quantitative PCR (RT-qPCR) and a bioinformatics analysis was performed to predict the microRNAs targeted by the validated circRNAs. From the circRNA expression profiles in the plasma of patients with IHs, 128 differentially expressed circRNAs were identified, of which 72 were upregulated and 56 were downregulated. The downregulated expression of three circRNAs [Homo sapiens (hsa)_circRNA_101566, hsa_circRNA_103546 and hsa_circRNA_103573] was verified using RT-qPCR. Gene Ontology term and Kyoto Encyclopedia of Genes and Genomes pathway analyses indicated that all identified networks participated in angiogenesis and tumor formation and progression. It was determined that hsa_circRNA_101566, which is able to regulate the mTOR signaling pathway, may be an important regulatory molecule in IH development and that targeting of hsa_miR_520c is able to indirectly regulate the vascular endothelial growth factor signaling pathway. Further studies are required to clarify these effects and the underlying mechanisms.

Sox11 Modified Tendon-Derived Stem Cells Promote the Repair of Osteonecrosis of Femoral Head

Osteonecrosis of the femoral head (ONFH) is a leading cause of mobility impairment which may lead to a total hip replacement. Recent studies have found tendon derived stem cells (TDSCs) might be an ideal cell source for musculoskeletal tissue regeneration. And our previous study has shown Sox11 could promote osteogenesis of bone marrow-derived MSCs. However, the effect of TDSCs or Sox11 over-expressing TDSCs (TDSCs-Sox11) on bone regeneration in ONFH has not been investigated. In the present study, TDSCs were infected with AAV carrying Sox11 or empty vector. We showed that Sox11 could promote the proliferation and osteogenic differentiation of TDSCs, as well as angiogenesis in vitro. The western blot analysis showed that Sox11 could activate the PI3K/Akt signaling pathway to promote osteogenesis of TDSCs. Finally, using a rabbit model of hormone-induced ONFH, our result demonstrated that local administration of TDSCs or TDSCs overexpressing Sox11 could accelerate bone regeneration in necrotic femoral heads, and TDSCs overexpressing Sox11 showed better effects. TDSCs over-expressing Sox11 might be a promising cell source for stem cell therapy to promote bone regeneration, such as ONFH, fracture, bone defect, and so on.

Comparison of the Therapeutic Effect of Allogeneic and Xenogeneic Small Extracellular Vesicles in Soft Tissue Repair

Purpose

Small extracellular vesicles (sEV) are a heterogeneous group of vesicles that consist of proteins, lipids and miRNA molecules derived from the cell of origin. Although xenogeneic sEV have been applied for soft tissue regeneration successfully, the regeneration effect of allogeneic and xenogeneic sEV has not been compared systematically.

Methods

Our previous study has shown that sEV derived from rat adipose tissue successfully induced neoadipose regeneration. In this study, sEV were isolated from rat adipose tissue (r-sEV-AT) and porcine adipose tissue (p-sEV-AT), the morphology, size distribution and marker proteins expression of r-sEV-AT and p-sEV-AT were characterized. Besides, the sEV/AT ratio was evaluated and compared between r-sEV-AT and p-sEV-AT. Rat adipose-derived stromal/stem cells (rASCs) and rat aorta endothelial cells (rECs) were adopted to test the cellular response to allogeneic and xenogeneic sEV-AT. The effects of allogeneic and xenogeneic sEV-AT on host cells migration and neoadipose formation were evaluated in a subcutaneous custom-designed model. A full-thickness skin wound healing model was used to further compare the ability of allogeneic and xenogeneic sEV-AT in inducing complex soft tissue regeneration.

Results

p-sEV-AT showed similar morphology and size distribution to r-sEV-AT. Marker proteins of sEV were detected in both r-sEV-AT and p-sEV-AT. The sEV/AT ratio of porcine was slightly higher than that of rat. The effects of r-sEV-AT and p-sEV-AT on the differentiation of rASCs and rECs showed no significant difference. When allogeneic and xenogeneic sEV-AT were subcutaneously implanted into the back of SD rats, the host cells chemotactic infiltration was observed in 1 week and neoadipose tissue formation was induced in 8 weeks; no significant difference was observed between allogeneic and xenogeneic sEV-AT. For complex soft tissue regeneration, both allogeneic and xenogeneic sEV-AT significantly promoted wound re-epithelialization, granulation tissue formation and hair follicle regeneration and then accelerated skin wound healing.

Conclusion

Our results demonstrated that sEV derived from the same tissues of different species might be loaded with similar therapeutic substance benefitting tissue repair and regeneration, and paved the way for future research aimed at xenogeneic sEV application.

1,25(OH)2D3 Strengthens the Vasculogenesis of Multipotent Mesenchymal Stromal Cells from Rat Bone Marrow by Regulating the PI3K/AKT Pathway

Background

Multipotent mesenchymal stromal cells (MSCs) have recently been reported to promote vasculogenesis by differentiating into endothelial cells and releasing numerous cytokines and paracrine factors. However, due to low cell activity, their potential for clinical application is not very satisfactory. This study aimed to explore the effects and mechanisms of 1,25-dihydroxyvitamin D (1,25(OH)₂D₃) on the vasculogenesis of MSCs.

Methods

MSCs were isolated from the femurs and tibias of rats and characterized by flow cytometry. After treatment with different concentrations of 1,25(OH)₂D₃ (0 µM, 0.1 µM and 1 µM), the proliferation of MSCs was analyzed by Cell Counting Kit-8 (CCK-8), and the migratory capability was measured by Transwell assays and cell scratch tests. Capillary-like structure formation was observed by using Matrigel. Western blotting was used to detect the expression of FLK-1 and vWF to investigate the differentiation of MSCs into endothelial cells. Western blotting and gelatin zymography were used to detect the expression and activities of VEGF, MMP-2 and MMP-9 secreted by MSCs under the influence of 1,25(OH)₂D_3. Finally, the VDR antagonist pyridoxal-5-phosphate (P5P) and the PI3K/AKT pathway inhibitor LY294002 were utilized to test the phosphorylation levels of key kinases in the PI3K/AKT pathway by Western blotting and the formation of capillary-like structures in Matrigel.

Results

The proliferation and migratory capability of MSCs and the ability of MSCs to form a tube-like structure in Matrigel were enhanced after treatment with 1,25(OH)₂D₃. Moreover, MSCs treated with 1,25(OH)₂D₃ showed high expression of vWF and Flk-1. There was a significant increase in the expression of VEGF, MMP-2 and MMP-9 secreted by MSCs treated with 1,25(OH)₂D_3, as well as in the activity of MMP-2 and MMP-9. The phosphorylation level of AKT increased with time after 1,25(OH)₂D₃ treatment, while LY294002 weakened AKT phosphorylation. In addition, the ability to form capillary-like structures was reduced when the VDR and PI3K/AKT pathways were blocked.

Conclusion

This study confirmed that 1,25(OH)₂D₃ treatment can strengthen the ability of MSCs to promote vasculogenesis in vitro, and the mechanism may be related to the activation of the PI3K/AKT pathway.

Relevance of Oxygen Concentration in Stem Cell Culture for Regenerative Medicine

The key hallmark of stem cells is their ability to self-renew while keeping a differentiation potential. Intrinsic and extrinsic cell factors may contribute to a decline in these stem cell properties, and this is of the most importance when culturing them. One of these factors is oxygen concentration, which has been closely linked to the maintenance of stemness. The widely used environmental 21% O₂ concentration represents a hyperoxic non-physiological condition, which can impair stem cell behaviour by many mechanisms. The goal of this review is to understand these mechanisms underlying the oxygen signalling pathways and their negatively-associated consequences. This may provide a rationale for culturing stem cells under physiological oxygen concentration for stem cell therapy success, in the field of tissue engineering and regenerative medicine.

A Novel Regulatory Axis, CHD1L-MicroRNA 486-Matrix Metalloproteinase 2, Controls Spermatogonial Stem Cell Properties

Spermatogonial stem cells (SSCs) are unipotent germ cells that are at the foundation of spermatogenesis and male fertility. However, the underlying molecular mechanisms governing SSC stemness and growth properties remain elusive. We have recently identified chromodomain helicase/ATPase DNA binding protein 1-like (Chd1l) as a novel regulator for SSC survival and self-renewal, but how these functions are controlled by Chd1l remains to be resolved. Here, we applied high-throughput small RNA sequencing to uncover the microRNA (miRNA) expression profiles controlled by Chd1l and showed that the expression levels of 124 miRNA transcripts were differentially regulated by Chd1l in SSCs. KEGG pathway analysis shows that the miRNAs that are differentially expressed upon Chd1l repression are significantly enriched in the pathways associated with stem cell pluripotency and proliferation. As a proof of concept, we demonstrate that one of the most highly upregulated miRNAs, miR-486, controls SSC stemness gene expression and growth properties. The matrix metalloproteinase 2 (MMP2) gene has been identified as a novel miR-486 target gene in the context of SSC stemness gene regulation and growth properties. Data from cotransfection experiments showed that Chd1l, miR-486, and MMP2 work in concert in regulating SSC stemness gene expression and growth properties. Finally, our data also revealed that MMP2 regulates SSC stemness gene expression and growth properties through activating β-catenin signaling by cleaving N-cadherin and increasing β-catenin nuclear translocation. Our data demonstrate that Chd1l-miR-486-MMP2 is a novel regulatory axis governing SSC stemness gene expression and growth properties, offering a novel therapeutic opportunity for treating male infertility.

An experimental strategy unveiling exosomal microRNAs 486-5p, 181a-5p and 30d-5p from hypoxic tumour cells as circulating indicators of high-risk rectal cancer

Tumour hypoxia contributes to poor treatment outcome in locally advanced rectal cancer (LARC) and circulating extracellular vesicles (EVs) as potential biomarkers of tumour hypoxia and adverse prognosis have not been fully explored. We examined EV miRNAs from hypoxic colorectal cancer cell lines as template for relevant miRNAs in LARC patients participating in a prospective biomarker study (NCT01816607). Five cell lines were cultured under normoxia (21% O₂) or hypoxia (0.2% O₂) for 24 h, and exosomes were isolated by differential ultracentrifugation. Using a commercial kit, exosomes were precipitated from 24 patient plasma samples collected at the time of diagnosis. Exosome size distribution and protein cargo were determined by cryo-electron microscopy, nanoparticle tracking analysis, immunoblotting and flow cytometry. The vesicles harboured strong cell line-specific miRNA profiles with 35 unique miRNAs differentially expressed between hypoxic and normoxic cells. Six of these miRNAs were considered candidate-circulating markers of tumour hypoxia in the patients based on the frequency or magnitude of variance in hypoxic versus normoxic cell line experiments and prevalence in patient plasma. Of these, low plasma levels of exosomal miR-486-5p and miR-181a-5p were associated with organ-invasive primary tumour (p = 0.029) and lymph node metastases (p = 0.024), respectively, both attributes of adverse LARC prognosis. In line with this, the plasma level of exosomal miR-30d-5p was elevated in patients who experienced metastatic progression (p = 0.036). Our strategy confirmed that EVs from colorectal cancer cell lines were exosomes containing the oxygen-sensitive miRNAs 486-5p, 181a-5p and 30d-5p, which were retrieved as circulating markers of high-risk LARC.

MicroRNA-21 Overexpression Promotes the Neuroprotective Efficacy of Mesenchymal Stem Cells for Treatment of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) has high morbidity and mortality, with no effective treatment at present. One possible therapeutic strategy involves the use of mesenchymal stem cells (MSCs), which have shown promise in experimental models and have great potential for treating nervous illnesses in humans. However, many deficiencies in MSC treatment still need to be addressed, including their poor survival rate post-transplantation. Previously, we reported that the microRNA-21 (miR-21) is downregulated in ICH patients' blood and brain tissue. In this study, we aimed to examine its role and therapeutic efficacy in ICH using miR-21-overexpressing MSCs. We found that this microRNA can enhance MSC survival and recovery of neurological function in ICH rats. Its mechanism of action involves reduced neuronal apoptosis. In addition, we demonstrated that miR-21 can be transported to neurons through exosomes derived from MSCs and that it can target transient receptor potential melastatin 7 (TRPM7) to alleviate neuronal injury following ICH. We also observed that the NF-κB pathway is involved in the regulation of miR-21 in neural cells. In conclusion, miR-21 significantly enhances the survival of MSCs in ICH, and miR-21-overexpressing MSCs clearly improved neurological function in ICH rats. Transplantation of miR-21-overexpressing MSCs may, therefore, provide an effective strategy for neuroprotection and treatment of cerebrovascular diseases.

miRNA array analysis of plasma miRNA alterations in rats exposed to a high altitude hypoxic environment

In the present study, the microRNA (miRNA) expression profiles of rats exposed to high altitude hypoxia and normal conditions were obtained from miRNA array analysis. Bioinformatics analyses, including the use of the Gene Oncology and Kyoto Encyclopedia of Genes and Genomes databases, were used to identify the genes and pathways, which were specifically associated with high altitude hypoxic environment‑associated miRNAs. A total of 26 miRNAs were differentially expressed in the two groups, comprising six upregulated and 20 downregulated miRNAs. In the present study, a novel pattern of upregulated miRNAs and their associated pathways were constructed, including proteoglycans in cancer, spliceosome, gluamatergic synapse, glycolysis/gluconeogenesis, Foxo, cGMP‑PKG and p53 signaling pathways, which may provide novel targets for diagnosing and understanding the mechanism of high altitude hypoxia‑induced disease.

Therapeutic potential of microRNAs in osteoporosis function by regulating the biology of cells related to bone homeostasis

MicroRNAs (miRNAs) are novel regulatory factors that play important roles in numerous cellular processes through the posttranscriptional regulation of gene expression. Recently, deregulation of the miRNA-mediated mechanism has emerged as an important pathological factor in osteoporosis. However, a detailed molecular mechanism between miRNAs and osteoporosis is still not available. In this review, the roles of miRNAs in the regulation of cells related to bone homeostasis as well as miRNAs that deregulate in human or animal are discussed. Moreover, the miRNAs that act as clusters in the biology of cells in the bone microenvironment and the difference of some important miRNAs for bone homeostasis between bone and other organs are mentioned. Overall, miRNAs that contribute to the pathogenesis of osteoporosis and their therapeutic potential are considered.

Gestational Hypoxia and Developmental Plasticity

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.

* Glioblastoma Exosomes for Therapeutic Angiogenesis in Peripheral Ischemia

Peripheral ischemia as a result of occlusive vascular disease is a widespread problem in patients older than the age of 65. Angiogenic therapies that can induce microvascular growth have great potential for providing a long-lasting solution for patients with ischemia and would provide an appealing alternative to surgical and percutaneous interventions. However, many angiogenic therapies have seen poor efficacy in clinical trials, suggesting that patients with long-term peripheral ischemia have considerable therapeutic resistance to angiogenic stimuli. Glioblastoma is one of the most angiogenic tumor types, inducing robust vessel growth in the area surrounding the tumor. One major angiogenic mechanism used by the tumor cells to induce blood vessel growth is the production of exosomes and other extracellular vesicles that can carry pro-angiogenic and immunomodulatory signals. Here, we explored whether the pro-angiogenic aspects of glioblastoma-derived exosomes could be harnessed to promote angiogenesis and healing in the context of peripheral ischemic disease. We demonstrate that the exosomes derived from glioblastoma markedly enhance endothelial cell proliferation and increase endothelial tubule formation in vitro. An analysis of the microRNA expression using next generation sequencing identified that exosomes contained a high concentration of miR-221. In addition, we found that glioblastoma exosomes contained significant amounts of the proteoglycans glypican-1 and syndecan-4, which can serve as co-receptors for angiogenic factors, including fibroblast growth factor-2 (FGF-2). In a hindlimb ischemia model in mice, we found that the exosomes promoted enhanced revascularization in comparison to control alginate gels and FGF-2 treatment alone. Taken together, our results support the fact that glioblastoma-derived exosomes have powerful effects in increasing revascularization in the context of peripheral ischemia.

Changes in plasma miR-9, miR-16, miR-205 and miR-486 levels after non-small cell lung cancer resection

PURPOSE

The majority of non-small cell lung cancer (NSCLC) patients presents with an advanced-stage disease and, consequently, exhibits a poor overall survival rate. We aimed to assess changes in plasma miR-9, miR-16, miR-205 and miR-486 levels and their potential as biomarkers for the diagnosis and monitoring of NSCLC patients.

METHODS

Plasma was collected from 50 healthy donors and from NSCLC patients before surgery (n = 61), 1 month after surgery (n = 37) and 1 year after surgery (n = 14). microRNA levels were quantified using qRT-PCR.

RESULTS

We found in NSCLC patients before treatment, both with squamous cell carcinoma (SQCC) and adenocarcinoma (ADC), significantly higher plasma miR-16 and miR-486 levels than in healthy individuals. Pre-treatment miR-205 concentrations were found to be significantly higher in SQCC than in ADC patients, and only SQCC patients presented significantly higher circulating miR-205 levels than healthy donors. SQCC plasma miR-9 levels were not different from normal control levels, but in ADC they were found to be significantly decreased. A combination of plasma miR-16, miR-205 and miR-486 measurements was found to discriminate NSCLC patients from healthy persons, with a specificity of 95% and a sensitivity of 80%. Following tumor resection, we found that the miR-9 and miR-205 levels significantly decreased, even below the normal level, whereas the increased miR-486 level persisted up to one year after surgery, and the miR-16 level decreased to normal. After tumor resection, none of the miR levels tested was found to relate to recurrence.

CONCLUSIONS

Our data indicate that miR-9, miR-16, miR-205 and miR-486 may serve as NSCLC biomarkers. The observed cancer-related pre- and post-operative changes in their plasma levels may not only reflect the presence of a primary cancer, but also of a systemic response to cancer.

Downregulation of miR-503 Promotes ESCC Cell Proliferation, Migration, and Invasion by Targeting Cyclin D1

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive cancers in China, but the underlying molecular mechanism of ESCC is still unclear. Involvement of microRNAs has been demonstrated in cancer initiation and progression. Despite the reported function of miR-503 in several human cancers, its detailed anti-oncogenic role and clinical significance in ESCC remain undefined. In this study, we examined miR-503 expression by qPCR and found the downregulation of miR-503 expression in ESCC tissue relative to adjacent normal tissues. Further investigation in the effect of miR-503 on ESCC cell proliferation, migration, and invasion showed that enhanced expression of miR-503 inhibited ESCC aggressive phenotype and overexpression of CCND1 reversed the effect of miR-503-mediated ESCC cell aggressive phenotype. Our study further identified CCND1 as the target gene of miR-503. Thus, miR-503 functions as a tumor suppressor and has an important role in ESCC by targeting CCND1.

MiR-486 regulates cardiomyocyte apoptosis by p53-mediated BCL-2 associated mitochondrial apoptotic pathway

BACKGROUND

Cardiomyocyte apoptosis is a common pathological manifestation that occurs in several heart diseases. This study aimed to explore the mechanism of microRNA-486 (miR-486) in cardiomyocyte apoptosis by interfering with the p53-activated BCL-2 associated mitochondrial pathway.

METHODS

miR-486 mimics and inhibitors were transfected into the primary cardiomyocytes of suckling Sprague-Dawley rat pups, and H₂O₂ was used to induce apoptosis. Flow cytometry and TUNEL were both used to detect cardiomyocyte apoptosis, while the relative mRNA transcript and protein levels of miR-486, p53, Bbc3, BCL-2, and cleaved caspase-3 were detected using RT-PCR and western blot analysis, respectively.

RESULTS

miR-486 overexpression significantly decreased the expressions of p53, Bbc3 and cleaved caspase-3 (P < 0.05), and BCL-2 expression was significantly increased (P < 0.05), which in turn caused a significant decrease in the rate of cardiomyocyte apoptosis (P < 0.05). In contrast, miR-486 silencing resulted in an elevated rate of cardiomyocyte apoptosis (P < 0.05).

CONCLUSION

miR-486 may regulate cardiomyocyte apoptosis via p53-mediated BCL-2 associated mitochondrial apoptotic pathway. Therefore, up-regulating miR-486 expression in cardiomyocytes can effectively reduce the activation of the BCL-2 associated mitochondrial apoptotic pathway, consequently protecting cardiomyocytes.

Differential microRNA expression in human placentas of term intra-uterine growth restriction that regulates target genes mediating angiogenesis and amino acid transport

Placental insufficiency leading to intrauterine growth restriction (IUGR) demonstrates perturbed gene expression affecting placental angiogenesis and nutrient transfer from mother to fetus. To understand the post-transcriptional mechanisms underlying such placental gene expression changes, our objective was to identify key non-coding microRNAs that express biological function. To this end, we initially undertook microarrays targeting microRNAs in a small sub-set of placentas of appropriate (AGA) versus small for gestational age (SGA) weight infants, and observed up-regulation of 97 miRs and down-regulation of 44 miRs in SGA versus AGA. In a larger cohort of samples (AGA, n = 21; SGA, n = 11; IUGR subset, n = 5), we validated by qRT-PCR differential expression of three specific microRNAs (miR-10b, -363 and -149) that target genes mediating angiogenesis and nutrient transfer. Validation yielded an increase in miR-10b and -363 expression of ~2.5-fold (p<0.02 each) in SGA versus AGA, and of ~3-fold (p<0.005) in IUGR versus AGA, with no significant change despite a trending increase in miR-149. To further establish a cause-and-effect paradigm, employing human HTR8 trophoblast cells, we assessed the effect of nutrient deprivation on miR expression and inhibition of endogenous miRs on target gene expression. In-vitro nutrient deprivation (~50%) increased the expression of miR-10b and miR-149 by 1.5-fold (p<0.02) while decreasing miR-363 (p<0.0001). Inhibition of endogenous miRs employing antisense sequences against miR-10b, -363 and -149 revealed an increase respectively in the expression of the target genes KLF-4 (transcription factor which regulates angiogenesis), SNAT1 and 2 (sodium coupled neutral amino acid transporters) and LAT2 (leucine amino acid transporter), which translated into a similar change in the corresponding proteins. Finally to establish functional significance we performed dual-luciferase reporter assays with 3'-insertion of miR-10b alone and observed a ~10% reduction in the 5'-luciferase activity versus the control. Lastly, we further validated by microarray and employing MirWalk software that the pathways and target genes identified by differentially expressed miRs in SGA/IUGR compared to AGA are consistent in a larger cohort. We have established the biological significance of various miRs that target common transcripts mediating pathways of importance, which are perturbed in the human IUGR placenta.

microRNAs in lipoprotein and lipid metabolism: from biological function to clinical application

microRNAs (miRNAs) are short (~22 nucleotides), non-coding, single-stranded RNA molecules that regulate the expression of target genes by partial sequence-specific base-pairing to the targeted mRNA 3'UTR, blocking its translation, and promoting its degradation or its sequestration into processing bodies. miRNAs are important regulators of several physiological processes including developmental and metabolic functions, but their concentration in circulation has also been reported to be altered in many pathological conditions such as familial hypercholesterolemia, cardiovascular diseases, obesity, type 2 diabetes, and cancers. In this review, we focus on the role of miRNAs in lipoprotein and lipid metabolism, with special attention to the well-characterized miR-33a/b, and on the huge potential of miRNAs for clinical application as biomarkers and therapeutics in the context of cardiometabolic diseases.

Cellularizing hydrogel-based scaffolds to repair bone tissue: How to create a physiologically relevant micro-environment?

Tissue engineering is a promising alternative to autografts or allografts for the regeneration of large bone defects. Cell-free biomaterials with different degrees of sophistication can be used for several therapeutic indications, to stimulate bone repair by the host tissue. However, when osteoprogenitors are not available in the damaged tissue, exogenous cells with an osteoblast differentiation potential must be provided. These cells should have the capacity to colonize the defect and to participate in the building of new bone tissue. To achieve this goal, cells must survive, remain in the defect site, eventually proliferate, and differentiate into mature osteoblasts. A critical issue for these engrafted cells is to be fed by oxygen and nutrients: the transient absence of a vascular network upon implantation is a major challenge for cells to survive in the site of implantation, and different strategies can be followed to promote cell survival under poor oxygen and nutrient supply and to promote rapid vascularization of the defect area. These strategies involve the use of scaffolds designed to create the appropriate micro-environment for cells to survive, proliferate, and differentiate in vitro and in vivo. Hydrogels are an eclectic class of materials that can be easily cellularized and provide effective, minimally invasive approaches to fill bone defects and favor bone tissue regeneration. Furthermore, by playing on their composition and processing, it is possible to obtain biocompatible systems with adequate chemical, biological, and mechanical properties. However, only a good combination of scaffold and cells, possibly with the aid of incorporated growth factors, can lead to successful results in bone regeneration. This review presents the strategies used to design cellularized hydrogel-based systems for bone regeneration, identifying the key parameters of the many different micro-environments created within hydrogels.

Exosomal miR-486 regulates hypoxia-induced erythroid differentiation of erythroleukemia cells through targeting Sirt1

MicroRNAs (miRNAs) regulate the hypoxia-induced erythroid differentiation of hematopoietic cells. In this study, we identified that miR-486 was a rapid response miRNA to hypoxia in erythroleukemia TF-1 cells. Hypoxia exposure increased both intracellular and miR-486 levels of TF-1 cells. Ectopic miR-486 expression enhanced the growth and erythroid differentiation of TF-1 cells, whereas miR-486 inhibition suppressed their growth and erythroid differentiation. Treatment of TF-1 and cord blood CD34+ cells with exogenous containing miR-486 resulted in an increase of intracellular miR-486 level and enhanced erythroid differentiation. Furthermore, we identified that Sirt1 is a miR-486 target gene which modulates hypoxia-induced erythroid differentiation of TF-1 cells. Thus we identified a novel miRNA regulatory network that contributes to hypoxia-induced erythroid differentiation of hematopoietic cells.

Stem/progenitor cells and obstructive sleep apnea syndrome - new insights for clinical applications

Obstructive sleep apnea syndrome (OSAS) is a widespread disorder, characterized by recurrent upper airway obstruction during sleep, mostly as a result of complete or partial pharyngeal obstruction. Due to the occurrence of frequent and regular hypoxic events, patients with OSAS are at increased risk of cardiovascular disease, stroke, metabolic disorders, occupational errors, motor vehicle accidents and even death. Thus, OSAS has severe consequences and represents a significant economic burden. However, some of the consequences, as well as their costs can be reduced with appropriate detection and treatment. In this context, the recent advances that were made in stem cell biology knowledge and stem cell - based technologies hold a great promise for various medical conditions, including respiratory diseases. However, the investigation of the role of stem cells in OSAS is still recent and rather limited, requiring further studies, both in animal models and humans. The goal of this review is to summarize the current state of knowledge regarding both lung resident as well as circulating stem/progenitor cells and discuss existing controversies in the field in order to identify future research directions for clinical applications in OSAS. Also, the paper highlights the requisite for inter-institutional, multi-disciplinary research collaborations in order to achieve breakthrough results in the field.

Posttranscriptional and transcriptional regulation of endothelial nitric-oxide synthase during hypoxia: the role of microRNAs

Understanding the cellular pathways that regulate endothelial nitric oxide (eNOS, NOS3) expression and consequently nitric oxide (NO) bioavailability during hypoxia is a necessary aspect in the development of novel treatments for cardiovascular disorders. eNOS expression and eNOS-dependent NO cellular signaling during hypoxia promote an equilibrium of transcriptional and posttranscriptional molecular mechanisms that belong to both proapoptotic and survival pathways. Furthermore, NO bioavailability results not only from eNOS levels, but also relies on the presence of eNOS substrate and cofactors, the phosphorylation status of eNOS, and the presence of reactive oxygen species (ROS) that can inactivate eNOS. Since both NOS3 levels and these signaling pathways can also be a subject of posttranscriptional modulation by microRNAs (miRNAs), this class of short noncoding RNAs contribute another level of regulation for NO bioavailability. As miRNA antagomirs or specific target protectors could be used in therapeutic approaches to regulate NO levels, either by changing NOS3 mRNA stability or through factors governing eNOS activity, it is critical to understand their role in governing eNOS activity during hypoxa. In contrast to a large number of miRNAs reported to the change eNOS expression during hypoxia, only a few miRNAs modulate eNOS activity. Furthermore, impaired miRNA biogenesis leads to NOS3 mRNA stabilization under hypoxia. Here we discuss the recent studies that define miRNAs’ role in maintaining endothelial NO bioavailability emphasizing those miRNAs that directly modulate NOS3 expression or eNOS activity.