Exploring the Mechanism of CircRNA-vgll3 in Osteogenically Differentiated Human Bone Marrow Mesenchymal Stem Cells

Objective:To explore the mechanism of circRNA-vgll3 in osteogenic differentiation of human bone marrow mesenchymal stem cells.Methods:BMSCs cells were transfected with circRNA-vgll3,and divided into circRNA-vgll3 high-level group,circRNA-vgll3 low-level group,and negative control group(circRNA-vgll3 not transfected)according to the amount of transfection.The proliferation and apoptosis of BMSCs osteoblasts in each group were analyzed,and the alkaline phosphatase(ALP)activity,type I collagen gray value,bone morphogenetic protein 2(BMP-2),Runx2 protein,and mRNA expression levels were detected.Results:The circRNA-vgll3 low-level group had a significant inhibitory effect on the proliferation of BMSCs osteoblasts,and the apoptosis rate of the circRNA-vgll3 low-level group was significantly higher than that of the circRNA-vgll3 high-level group(P<0.05);ALP activity,type I collagen gray value,BMP-2,Runx2 protein,and mRNA expression levels in the high-level circRNA-vgll3 group were significantly higher than those in the low-level circRNA-vgll3 group,and the difference was statistically significant(P<0.05).Conclusion:Overexpression of circRNA-vgll3 can promote the osteogenic differentiation ability of BMSCs,while low expression of circRNA-vgll3 can inhibit the osteogenic differentiation ability of BMSCs.The main mechanism of action is that circRNA-vgll3 can affect osteogenic differentiation by regulating the Runx2 protein.

The genomic landscapes of histone H3-Lys9 modifications of gene promoter regions and expression profiles in human bone marrow mesenchymal stem cells

Mesenchymal stem cells （MSCs） of nonembryonic origins possess the proliferation and multi-lineage differentiation potentials. It has been established that epigenetic mechanisms could be critical for determining the fate of stem cells, and MSCs derived from different origins exhibited different expression profiles individually to a certain extent. In this study, ChiP-on-chip was used to generate genome-wide histone H3-Lys9 acetylation and dimethylation profiles at gene promoters in human bone marrow MSCs. We showed that modifications of histone H3-Lys9 at gene promoters correlated well with mRNA expression in human bone marrow MSCs. Functional analysis revealed that many key cellular pathways in human bone marrow MSC self-renewal, such as the canonical signaling pathways, cell cycle pathways and cytokine related pathways may be regulated by H3-Lys9 modifications. These data suggest that gene activation and silencing affected by H3-Lys9 acetylation and dimethylation, respectively, may be essential to the maintenance of human bone marrow MSC self-renewal and multi-potency.

Human bone marrow mesenchymal stem cell transplantation attenuates axonal injury in stroke rats

Previous studies have shown that transplantation of human bone marrow mesenchymal stem cells promotes neural functional recovery after stroke, but the neurorestorative mechanisms remain largely unknown. We hypothesized that functional recovery of myelinated axons may be one of underlying mechanisms. In this study, an ischemia/reperfusion rat model was established using the middle cerebral artery occlusion method. Rats were used to test the hypothesis that intravenous transplantation of human bone marrow mesenchyrnal stem cells through the femoral vein could exert neuroprotective effects against cerebral ischemia via a mechanism associated with the ability to attenuate axonal injury. The results of behavioral tests, infarction volume analysis and immunohistochemistry showed that cerebral ischemia caused severe damage to the myelin sheath and axons. After rats were intravenously transplanted with human bone marrow mesenchymal stem cells, the levels of axon and myelin sheath-related proteins, including microtubule-associated protein 2, myelin basic protein, and growth-associated protein 43, were elevated, infarct volume was decreased and neural function was improved in cerebral ischemic rats. These findings suggest that intravenously transplanted human bone marrow mesenchymal stem cells promote neural function. Possible mechanisms underlying these beneficial effects include resistance to demyelination after cerebral ischemia, prevention of axonal degeneration, and promotion of axonal regeneration.

Bioactive materials from berberine-treated human bone marrow mesenchymal stem cells promote alveolar bone regeneration by regulating macrophage polarization

Alveolar bone regeneration has been strongly linked to macrophage polarization.M1 macrophages aggravate alveolar bone loss,whereas M2 macrophages reverse this process.Berberine(BBR),a natural alkaloid isolated and refined from Chinese medicinal plants,has shown therapeutic effects in treating metabolic disorders.In this study,we first discovered that culture supernatant(CS)collected from BBR-treated human bone marrow mesenchymal stem cells(HBMSCs)ameliorated periodontal alveolar bone loss.CS from the BBR-treated HBMSCs contained bioactive materials that suppressed the M1 polarization and induced the M2 polarization of macrophages in vivo and in vitro.To clarify the underlying mechanism,the bioactive materials were applied to different animal models.We discovered macrophage colony-stimulating factor(M-CSF),which regulates macrophage polarization and promotes bone formation,a key macromolecule in the CS.Injection of pure M-CSF attenuated experimental periodontal alveolar bone loss in rats.Colony-stimulating factor 1 receptor(CSF1R)inhibitor or anti-human M-CSF(M-CSF neutralizing antibody,Nab)abolished the therapeutic effects of the CS of BBR-treated HBMSCs.Moreover,AKT phosphorylation in macrophages was activated by the CS,and the AKT activator reversed the negative effect of the CSF1R inhibitor or Nab.These results suggest that the CS of BBR-treated HBMSCs modulates macrophage polarization via the M-CSF/AKT axis.Further studies also showed that CS of BBR-treated HBMSCs accelerated bone formation and M2 polarization in rat teeth extraction sockets.Overall,our findings established an essential role of BBR-treated HBMSCs CS and this might be the first report to show that the products of BBR-treated HBMSCs have active effects on alveolar bone regeneration.

Triple-modal imaging of stem-cells labeled with multimodal nanoparticles, applied in a stroke model

BACKGROUND Mesenchymal stem cells(MSCs) have been widely tested for their therapeutic efficacy in the ischemic brain and have been shown to provide several benefits. A major obstacle to the clinical translation of these therapies has been the inability to noninvasively monitor the best route, cell doses, and collateral effects while ensuring the survival and effective biological functioning of the transplanted stem cells. Technological advances in multimodal imaging have allowed in vivo monitoring of the biodistribution and viability of transplanted stem cells due to a combination of imaging technologies associated with multimodal nanoparticles(MNPs) using new labels and covers to achieve low toxicity and longtime residence in cells.AIM To evaluate the sensitivity of triple-modal imaging of stem cells labeled with MNPs and applied in a stroke model.METHODS After the isolation and immunophenotypic characterization of human bonemarrow MSCs(hBM-MSCs), our team carried out lentiviral transduction of these cells for the evaluation of bioluminescent images(BLIs) in vitro and in vivo. In addition, MNPs that were previously characterized(regarding hydrodynamic size, zeta potential, and optical properties), and were used to label these cells,analyze cell viability via the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay and BLI analysis, and quantify the internalization process and iron load in different concentrations of MNPs via magnetic resonance imaging(MRI),near-infrared fluorescence(NIRF), and inductively coupled plasma-mass spectrometry(ICP-MS). In in vivo analyses, the same labeled cells were implanted in a sham group and a stroke group at different times and under different MNP concentrations(after 4 h or 6 d of cell implantation) to evaluate the sensitivity of triple-modal images.RESULTS hBM-MSC collection and isolation after immunophenotypic characterization were demonstrated to be adequate in hBM samples. After transduction of these cells with luciferase(hBM-MSCLuc), we detected a maximum BLI intensity of 2.0 x10^8 photons/s in samples of 10~6 hBM-MSCs. Analysis of the physicochemical characteristics of the MNPs showed an average hydrodynamic diameter of 38.2 ±0.5 nm, zeta potential of 29.2 ± 1.9 mV and adequate colloidal stability without agglomeration over 18 h. The signal of iron load internalization in hBM-MSCLuc showed a close relationship with the corresponding MNP-labeling concentrations based on MRI, ICP-MS and NIRF. Under the highest MNP concentration, cellular viability showed a reduction of less than 10% compared to the control.Correlation analysis of the MNP load internalized into hBM-MSCLuc determined via the MRI, ICP-MS and NIRF techniques showed the same correlation coefficient of 0.99. Evaluation of the BLI, NIRF, and MRI signals in vivo and ex vivo after labeled hBM-MSCLuc were implanted into animals showed differences between different MNP concentrations and signals associated with different techniques(MRI and NIRF; 5 and 20 μg Fe/mL; P < 0.05) in the sham groups at 4 h as well as a time effect(4 h and 6 d; P < 0.001) and differences between the sham and stroke groups in all images signals(P < 0.001).CONCLUSION This study highlighted the importance of quantifying MNPs internalized into cells and the efficacy of signal detection under the triple-image modality in a stroke model.

Study on bilibrubin induced apoptosis of human bone marrow mesenchymal stem cells

Objective To investigate the effects of bilirubin on human bone marrow mesenchymal stem cell(BMMSC)and to provide the evidence for selecting patients with liver function failure suitable for BMMSC transplantation therapy.Methods Bilirubin of different concentration(0,10,20,30,40 and 50μmol/L)was separately added

Human bone marrow mesenchymal stem cell-derived extracellular vesicles inhibit shoulder stiffness via let-7a/Tgfbr1 axis

Shoulder stiffness(SS)is a common shoulder disease characterized by increasing pain and limited range of motion.SS is considered to be an inflammatory and fibrotic disorder pathologically.However,there is no consensus on the most effective conservative treatment for fibrosis.Given that human Bone Marrow Mesen-chymal Stem Cell-derived extracellular vesicles(BMSC-EVs)displayed promising therapeutic effects for various tissues,we investigated the therapeutic effect of BMSC-EVs on fibrosis in a mice immobilization model and two cell models.By conducting a series of experiments,we found that BMSC-EVs can significantly inhibit the fibrogenic process both in vitro and in vivo.In detail,BMSC-EVs suppressed the aberrant proliferation,high collagen production capacity,and activation of fibrotic pathways in TGF-β-stimulated fibroblasts in vitro.Besides,in vivo,BMSC-EVs reduced cell infiltration,reduced fibrotic tissue in the shoulder capsule,and improved shoulder mobility.In addition,via exosomal small RNA sequencing and qPCR analysis,let-7a-5p was verified to be the highest expressed miRNA with predicted antifibrotic capability in BMSC-EVs.The antifibrotic capacity of BMSC-EVs was significantly impaired after the knockdown of let-7a-5p.Moreover,we discovered that the mRNA of TGFBR1(the membrane receptor of transforming growth factorβ)was the target of let-7a-5p.Together,these findings elucidated the antifibrotic role of BMSC-EVs in shoulder capsular fibrosis.This study clarifies a new approach using stem cell-derived EVs therapy as an alternative to cell therapy,which may clinically benefit patients with SS in the future.