Role and mechanism of microRNA-21 in H2O2-induced apoptosis in bone marrow mesenchymal stem cells. J Clin Neurosci. 2016;27:154-160. [PMID: 26810470 DOI: 10.1016/j.jocn.2015.07.029]

Protective Effects of Water Extract of Fructus Ligustri Lucidi against Oxidative Stress-Related Osteoporosis In Vivo and In Vitro

Fructus Ligustri Lucidi (FLL) is the fruit of Ligustrum lucidum Ait and is a component of many kidney-tonifying traditional Chinese medicine formulae for treating osteoporosis. Accumulating evidence has linked oxidative stress with the progression of bone diseases. The present study aimed to identify the effects of FLL on oxidative stress-related osteoporosis in vivo and in vitro. To construct animal models, we utilized d-galactose (D-gal) injection to induce oxidative stress combined with a low calcium (the exact percentage in the diet was 0.1%) diet. Thirteen-week-old Kunming female mice were gavaged with water extract of FLL for 20 days. Then, eight-month-old Kunming female mice were treated with FLL under standard administration and diet as the aged group. In vitro, MC3T3-E1 cells stimulated by H₂O₂ were treated with FLL for 24 h. The micro-CT results showed that the modeling approach combining oxidative stress with a low calcium diet caused low conversion type osteoporosis in mice. FLL exerted a prominent effect on preventing osteoporosis by inhibiting oxidative stress, increasing bone mineral density (BMD), improving bone microstructure, and promoting osteoblast proliferation and osteoprotegerin (OPG) protein expression; however, FLL had no therapeutic effect on bone loss in aged mice. In conclusion, FLL showed outstanding anti-bone loss ability both in vivo and in vitro and could probably be developed as a prophylactic agent for osteoporosis.

MicroRNA124 and microRNA21-5p regulate migration, proliferation and differentiation of rat bone marrow mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent stromal cells that can be a useful source of cells for the treatment of many diseases, including neurologic diseases. The curative effect of MSCs relies mostly on cell’s capacity of migration, proliferation and differentiation. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles on regulating various cell behaviors. Here, we report that miRNA-124 (miR124) and miRNA-21-5p (miR21-5p) display different regulatory roles on migration, proliferation and neuron differentiation of MSCs. MiR124 was shown greatly promoting MSCs migration and neuronal differentiation. MiR21-5p could significantly enhance the proliferation and neuronal differentiation ability of MSCs. MiR124 and miR21-5p synergistically promote differentiation of MSCs into neurons. Collectively, miR124 and miR21-5p can functionally regulate cell migration, proliferation and neuronal differentiation of MSCs. Therefore, miR124 and miR21-5p may be promising tools to improve transplantation efficiency for neural injury.

The miR-4739/DLX3 Axis Modulates Bone Marrow-Derived Mesenchymal Stem Cell (BMSC) Osteogenesis Affecting Osteoporosis Progression

Osteoporosis is a complex multifactorial disorder linked to various risk factors and medical conditions. Bone marrow-derived mesenchymal stem cell (BMSC) dysfunction potentially plays a critical role in osteoporosis pathogenesis. Herein, the study identified that miR-4739 was upregulated in BMSC cultures harvested from osteoporotic subjects. BMSCs were isolated from normal and osteoporotic bone marrow tissues and identified for their osteogenic differentiation potential. In osteoporotic BMSCs, miR-4739 overexpression significantly inhibited cell viability, osteoblast differentiation, mineralized nodule formation, and heterotopic bone formation, whereas miR-4739 inhibition exerted opposite effects. Through direct binding, miR-4739 inhibited distal-less homeobox 3 (DLX3) expression. In osteoporotic BMSCs, DLX3 knockdown also inhibited BMSC viability and osteogenic differentiation. Moreover, DLX3 knockdown partially attenuated the effects of miR-4739 inhibition upon BMSCs. Altogether, the miR-4739/DLX3 axis modulates the capacity of BMSCs to differentiate into osteoblasts, which potentially plays a role in osteoporosis pathogenesis. The in vivo and clinical functions of the miR-4739/DLX3 axis require further investigation.

MicroRNA-21 facilitates osteoblast activity

MicroRNAs are emerging as critical post-transcriptional modulators in bone remodeling, regulating the functions of osteoblasts and osteoclasts. Intercellular crosstalk between osteoblasts and osteoclasts is mediated by miR-21 that controls the bone homeostasis response, providing potential targets for the maintenance of osteoblast function. The aim of this study was to investigate the effects of miR-21 on osteoblast function, and to explore the underlying mechanism. Increased alkaline phosphatase (ALP) activity and accelerated matrix mineralization was observed in mouse pre-osteoblast MC3T3-E1 cells compared with the non-induction (control) group. MiR-21 positively regulates osteogenic differentiation and mineralization by facilitating the expression of key osteogenic factors (ALP, Runx2, Osteopontin (OPN), Osterix (OSX) and Mef2c) in MC3T3-E1 cells. Furthermore, a deficiency of miR-21 suppresses the expression of those factors at both the mRNA and protein levels, indicating that miR-21 is a positive regulator of osteoblastic differentiation. H-E staining, Azan staining, Masson's Trichrome staining and Toluidine blue staining were performed in jaw and femur tissues of miR-21 knockout (miR-21KO) and wild-type (WT) mice. Immunohistochemical staining revealed substantially lower levels of ALP, Runx2 and OSX expression in jaw and femur tissues of miR-21KO mice. A similar trend was observed in femur tissues using quantitative real-time (RT) PCR. A total of 17 osteogenesis-related mRNAs were found to be differentially expressed in miR-21KO femur tissues using Mouse Gene Expression Microarray analysis. GeneSpring and Ingenuity Pathway Analysis revealed several potential target genes that are involved in bone remodeling, such as IL-1β and HIF-1α. Several important pathways were determined to be facilitators of miR-21, which provides a reliable reference for future studies to elucidate the biological mechanisms of osteoblast function. Taken together, these results lead us to hypothesize a potential role for miR-21 in regulating osteoblast function, thus representing a potential biomarker of osteogenesis.

Mesenchymal stem cells secretome: The cornerstone of cell-free regenerative medicine

Mesenchymal stem cells (MSCs) are the most frequently used stem cells in clinical trials due to their easy isolation from various adult tissues, their ability of homing to injury sites and their potential to differentiate into multiple cell types. However, the realization that the beneficial effect of MSCs relies mainly on their paracrine action, rather than on their engraftment in the recipient tissue and subsequent differentiation, has opened the way to cell-free therapeutic strategies in regenerative medicine. All the soluble factors and vesicles secreted by MSCs are commonly known as secretome. MSCs secretome has a key role in cell-to-cell communication and has been proven to be an active mediator of immune-modulation and regeneration both in vitro and in vivo. Moreover, the use of secretome has key advantages over cell-based therapies, such as a lower immunogenicity and easy production, handling and storage. Importantly, MSCs can be modulated to alter their secretome composition to better suit specific therapeutic goals, thus, opening a large number of possibilities. Altogether these advantages now place MSCs secretome at the center of an important number of investigations in different clinical contexts, enabling rapid scientific progress in this field.

Piperlongumine induces apoptosis and G2/M phase arrest in human osteosarcoma cells by regulating ROS/PI3K/Akt pathway

Previous research has reported that piperlongumine exerts antitumor properties on several types of tumor cells. However, its effect on osteosarcoma cells remains unknown. This study aimed to investigate the antitumor effects of piperlongumine on osteosarcoma cells (MG63 and U2OS cells) in vitro and determined the underlying mechanism. Cell viability was measured using MTT assay. Cell apoptosis was assessed via AO/EB staining and flow cytometry apoptosis as well as western blot analysis. Cell cycle distribution was detected by flow cytometric cell cycle and western blot analysis. In our research, we found that piperlongumine induced apoptosis and G2/M phase arrest of MG63 cells. Western blot analysis not only confirmed the above results, but also demonstrated that piperlongumine induced apoptosis of osteosarcoma cells by activating Caspase-9-dependent apoptotic pathway. Furthermore, we also found that piperlongumine significantly induced apoptosis and cell cycle arrest of osteosarcoma cells by regulating ROS/PI3K/Akt signaling pathway. In summary, our findings suggested that piperlongumine inhibited osteosarcoma progression by promoting apoptosis of osteosarcoma cells. In addition, the underlying mechanism demonstrated that piperlongumine produced potent antitumor properties in osteosarcoma cells by regulating ROS/PI3K/Akt signaling pathway.

H₂O₂ Damages the Stemness of Rat Bone Marrow-Derived Mesenchymal Stem Cells: Developing a "Stemness Loss" Model

Background

The number of patients with spinal cord injury caused by motor vehicle accidents, violent injuries, and other types of trauma increases year by year, and bone marrow mesenchymal stem cell (BMSC) transplants are being widely investigated to treat this condition. However, the success rate of BMSCs transplants is relatively low due to the presence of oxidative stress in the new microenvironment. Our main goals in the present study were to evaluate the damaging effects of H₂O₂ on BMSCs and to develop a model of “stemness loss” using rat BMSCs.

Material/Methods

Bone marrow-derived mesenchymal stem cells were obtained from the bone marrow of young rats reared under sterile conditions. The stem cells were used after 2 passages following phenotypic identification. BMSCs were divided into 4 groups to evaluate the damaging effects of H₂O₂: A. blank control; B. 100 uM H₂O₂; C. 200 uM H₂O₂ and D. 300 uM H₂O₂. The ability of the BMSCs to differentiate into 3 cell lineages and their colony formation and migration capacities were analyzed by gene expression, colony formation, and scratch assays.

Results

The cells we obtained complied with international stem cell standards demonstrated by their ability to differentiate into 3 cell lineages. We found that 200–300 uM H₂O₂ had a significant effect on the biological behavior of BMSCs, including their ability to differentiate into 3 cell lineages, the expression of stemness-related proteins, and their migration and colony formation capacities.

Conclusions

H₂O₂ can damage the stemness ability of BMSCs at a concentration of 200–300 uM.

Physical Exercise Modulates miR-21-5p, miR-129-5p, miR-378-5p, and miR-188-5p Expression in Progenitor Cells Promoting Osteogenesis

Physical exercise is known to promote beneficial effects on overall health, counteracting risks related to degenerative diseases. MicroRNAs (miRNAs), short non-coding RNAs affecting the expression of a cell’s transcriptome, can be modulated by different stimuli. Yet, the molecular effects on osteogenic differentiation triggered by miRNAs upon physical exercise are not completely understood. In this study, we recruited 20 male amateur runners participating in a half marathon. Runners’ sera, collected before (PRE RUN) and after (POST RUN) the run, were added to cultured human mesenchymal stromal cells. We then investigated their effects on the modulation of selected miRNAs and the consequential effects on osteogenic differentiation. Our results showed an increased expression of miRNAs promoting osteogenic differentiation (miR-21-5p, miR-129-5p, and miR-378-5p) and a reduced expression of miRNAs involved in the adipogenic differentiation of progenitor cells (miR-188-5p). In addition, we observed the downregulation of PTEN and SMAD7 expression along with increased AKT/pAKT and SMAD4 protein levels in MSCs treated with POST RUN sera. The consequent upregulation of RUNX2 expression was also proven, highlighting the molecular mechanisms by which miR-21-5p promotes osteogenic differentiation. In conclusion, our work proposes novel data, which demonstrate how miRNAs may regulate the osteogenic commitment of progenitor cells in response to physical exercise.

Genetically Engineered-MSC Therapies for Non-unions, Delayed Unions and Critical-size Bone Defects

The normal bone regeneration process is a complex and coordinated series of events involving different cell types and molecules. However, this process is impaired in critical-size/large bone defects, with non-unions or delayed unions remaining a major clinical problem. Novel strategies are needed to aid the current therapeutic approaches. Mesenchymal stem/stromal cells (MSCs) are able to promote bone regeneration. Their beneficial effects can be improved by modulating the expression levels of specific genes with the purpose of stimulating MSC proliferation, osteogenic differentiation or their immunomodulatory capacity. In this context, the genetic engineering of MSCs is expected to further enhance their pro-regenerative properties and accelerate bone healing. Herein, we review the most promising molecular candidates (protein-coding and non-coding transcripts) and discuss the different methodologies to engineer and deliver MSCs, mainly focusing on in vivo animal studies. Considering the potential of the MSC secretome for bone repair, this topic has also been addressed. Furthermore, the promising results of clinical studies using MSC for bone regeneration are discussed. Finally, we debate the advantages and limitations of using MSCs, or genetically-engineered MSCs, and their potential as promoters of bone fracture regeneration/repair.

Salidroside suppresses the growth and invasion of human osteosarcoma cell lines MG63 and U2OS in vitro by inhibiting the JAK2/STAT3 signaling pathway

Previous research has reported that salidroside exerts antitumor properties on numerous types of tumor cells; however, its effect on osteosarcoma cells remains unknown. The present study aimed to investigate the effects of salidroside on the viability, apoptosis and invasion of osteosarcoma cells in vitro, and determine the underlying mechanism of action. The results of an MTT revealed that salidroside suppressed the viability of osteosarcoma cells (MG63 and U2OS cells) in a time- and concentration-dependent manner. The results of cell morphological analysis (profile observations and Hoechst 33258 staining) and the detection of apoptosis by flow cytometry further indicated that the decrease in osteosarcoma cell viability induced by salidroside was associated with cell apoptosis. Western blot analysis not only confirmed these results but also suggested that salidroside induced the apoptosis of osteosarcoma cells by activating the caspase-9-dependent apoptotic pathway. In addition, we reported that salidroside induced G₀/G₁ phase arrest and suppressed the invasion of osteosarcoma cells, as measured by flow cytometric cell cycle analysis and a Transwell invasion assay, respectively. Western blot analysis confirmed the aforementioned results. Furthermore, our findings demonstrated that salidroside induced the apoptosis, G₀/G₁ phase arrest and suppressed the invasion of osteosarcoma cells by inhibiting the janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway, as determined by western blot analysis. In summary, the findings of the present study suggested that salidroside may inhibit the progression of osteosarcoma by suppressing the growth and invasion of osteosarcoma cells. Furthermore, the investigations into the underlying mechanism demonstrated that salidroside exerted notable antitumor activity in osteosarcoma cells by inhibiting the JAK2/STAT3 signaling pathway.

[Effect of miR-21 down-regulated by H 2O 2 on osteogenic differentiation of MC3T3-E1 cells]

Objective

To explore the effect and mechanism of miR-21 down-regulated which was induced by H ₂O ₂ on osteogenic differentiation of MC3T3-E1 cells.

Methods

MC3T3-E1 cells were cultured and passaged, and the 7th generation cells were harvested to use in experiment. The MC3T3-E1 cells were treated with different concentrations (0, 40, 80, 160, and 320 μmol/L) of H ₂O ₂. The expression of miR-21 was detected by real-time quantitative PCR (RT-PCR) and the cell viability was determined by MTS. Then the appropriate concentration of H ₂O ₂ was obtained. To analyze the effect of H ₂O ₂ on osteogenic differentiation of MC3T3-E1 cells, the MC3T3-E1 cells were divided into blank control group (group A), H ₂O ₂ group (group B), osteogenic induction group (group C), and H ₂O ₂+osteogenic induction group (group D). The expression of miR-21 and the osteogenesis related genes expressions of Runx2, osteopontin (OPN), and collagen type Ⅰ alpha 1 (Col1a1) were detected by RT-PCR. The expression of phosphatase and tensin homolog (PTEN) was detected by Western blot. The extracellular calcium deposition was detected by alizarin red staining. To analyze the effect on osteogenic differentiation of MC3T3-E1 cells after the transfection of miR-21 inhibitor and siRNA-PTEN, the MC3T3-E1 cells were divided into H ₂O ₂ group (group A1), H ₂O ₂+osteogenic induction group (group B1), H ₂O ₂+osteogenic induction+miR-21 inhibitor group (group C1), and H ₂O ₂+osteogenic induction+miR-21 inhibitor negative control group (group D1); and H ₂O ₂ group (group A2), H ₂O ₂+osteogenic induction group (group B2), H ₂O ₂+osteogenic induction+siRNA-PTEN negative control group (group C2), and H ₂O ₂+osteogenic induction+siRNA-PTEN group (group D2). The osteogenesis related genes were detected by RT-PCR and the extracellular calcium deposition was detected by alizarin red staining.

Results

The results of MTS and RT-PCR showed that the appropriate concentration of H ₂O ₂ was 160 μmol/L. The expression of miR-21 was significantly lower in group B than in group A at 1 and 2 weeks ( P<0.05). The expression of miR-21 was significantly lower in group D than in group C at 1 and 2 weeks ( P<0.05). The expression of PTEN protein was significantly lower in group C than in groups A and D ( P<0.05). The mRNA expressions of Runx2, OPN, and Col1a1 were significantly lower in group D than in group C at 1 and 2 weeks ( P<0.05). The extracellular calcium deposition in group D was obviously less than that in group C. The expression of PTEN protein was significantly higher in group C1 than in group D1 ( P<0.05). The mRNA expressions of Runx2 and OPN were significantly lower in group C1 than in groups B1 and D1 at 1 and 2 weeks ( P<0.05). The mRNA expression of Col1a1 was significantly lower in group C1 than in groups B1 and D1 at 2 weeks ( P<0.05). The extracellular calcium deposition in group C1 was obviously less than those in groups B1 and D1. The mRNA expressions of OPN and Col1a1 were significantly higher in group D2 than in groups B2 and C2 at 1 week ( P<0.05). The extracellular calcium deposition in group D2 was obviously more than those in groups B2 and C2.

Conclusion

H ₂O ₂ inhibits the osteogenic differentiation of MC3T3-E1 cells, which may be induced by down-regulating the expression of miR-21.

Exosomes Derived from miR-214-Enriched Bone Marrow-Derived Mesenchymal Stem Cells Regulate Oxidative Damage in Cardiac Stem Cells by Targeting CaMKII

Cardiac stem cells (CSCs) have emerged as one of the most promising stem cells for cardiac protection. Recently, exosomes from bone marrow-derived mesenchymal stem cells (BMSCs) have been found to facilitate cell proliferation and survival by transporting various bioactive molecules, including microRNAs (miRs). In this study, we found that BMSC-derived exosomes (BMSC-exos) significantly decreased apoptosis rates and reactive oxygen species (ROS) production in CSCs after oxidative stress injury. Moreover, a stronger effect was induced by exosomes collected from BMSCs cultured under hypoxic conditions (Hypoxic-exos) than those collected from BMSCs cultured under normal conditions (Nor-exos). We also observed greater miR-214 enrichment in Hypoxic-exos than in Nor-exos. In addition, a miR-214 inhibitor or mimics added to modulate miR-214 levels in BMSC-exos revealed that exosomes from miR-214-depleted BMSCs partially reversed the effects of hypoxia-induced exosomes on oxidative damage in CSCs. These data further confirmed that miR-214 is the main effector molecule in BMSC-exos that protects CSCs from oxidative damage. miR-214 mimic and inhibitor transfection assays verified that CaMKII is a target gene of miR-214 in CSCs, with exosome-pretreated CSCs exhibiting increased miR-214 levels but decreased CaMKII levels. Therefore, the miR-214/CaMKII axis regulates oxidative stress-related injury in CSCs, such as apoptosis, calcium homeostasis disequilibrium, and excessive ROS accumulation. Collectively, these findings suggest that BMSCs release miR-214-containing exosomes to suppress oxidative stress injury in CSCs through CaMKII silencing.

Bone marrow mesenchymal stem cell-derived exosomal miR-21 protects C-kit+ cardiac stem cells from oxidative injury through the PTEN/PI3K/Akt axis

Stem cell (SC) therapy for ischemic cardiomyopathy is hampered by poor survival of the implanted cells. Recently, SC-derived exosomes have been shown to facilitate cell proliferation and survival by transporting various proteins and non-coding RNAs (such as microRNAs and lncRNAs). In this study, miR-21 was highly enriched in exosomes derived from bone marrow mesenchymal stem cells (MSCs). Interestingly, exosomes collected from hydrogen peroxide (H₂O₂)-treated MSCs (H-Exo) contained higher levels of miR-21 than exosomes released from MSCs under normal conditions (N-Exo). The pre-treatment of C-kit⁺ cardiac stem cells (CSCs) with H-Exos resulted in significantly increased levels of miR-21 and phosphor-Akt (pAkt) and decreased levels of PTEN, which is a known target of miR-21. AnnexinV-FITC/PI analysis further demonstrated that the degree of oxidative stress-induced apoptosis was markedly lower in H-Exo-treated C-kit⁺ CSCs than that in N-Exo-treated cells. These protective effects could be blocked by both a miR-21 inhibitor and the PI3K/Akt inhibitor LY294002. Therefore, exosomal miR-21 derived from H₂O₂-treated MSCs could be transported to C-kit⁺ cardiac stem cells to functionally inhibit PTEN expression, thereby activating PI3K/AKT signaling and leading to protection against oxidative stress-triggered cell death. Thus, exosomes derived from MSCs could be used as a new therapeutic vehicle to facilitate C-kit⁺ CSC therapies in the ischemic myocardium.

Umbilical cord extracts improve osteoporotic abnormalities of bone marrow-derived mesenchymal stem cells and promote their therapeutic effects on ovariectomised rats

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are the most valuable source of autologous cells for transplantation and tissue regeneration to treat osteoporosis. Although BM-MSCs are the primary cells responsible for maintaining bone metabolism and homeostasis, their regenerative ability may be attenuated in postmenopausal osteoporosis patients. Therefore, we first examined potential abnormalities of BM-MSCs in an oestrogen-deficient rat model constructed by ovariectomy (OVX-MSCs). Cell proliferation, mobilisation, and regulation of osteoclasts were downregulated in OVX-MSCs. Moreover, therapeutic effects of OVX-MSCs were decreased in OVX rats. Accordingly, we developed a new activator for BM-MSCs using human umbilical cord extracts, Wharton’s jelly extract supernatant (WJS), which improved cell proliferation, mobilisation and suppressive effects on activated osteoclasts in OVX-MSCs. Bone volume, RANK and TRACP expression of osteoclasts, as well as proinflammatory cytokine expression in bone tissues, were ameliorated by OVX-MSCs activated with WJS (OVX-MSCs-WJ) in OVX rats. Fusion and bone resorption activity of osteoclasts were suppressed in macrophage-induced and primary mouse bone marrow cell-induced osteoclasts via suppression of osteoclast-specific genes, such as Nfatc1, Clcn7, Atp6i and Dc-stamp, by co-culture with OVX-MSCs-WJ in vitro. In this study, we developed a new activator, WJS, which improved the functional abnormalities and therapeutic effects of BM-MSCs on postmenopausal osteoporosis.

The synergistic effect of strontium-substituted hydroxyapatite and microRNA-21 on improving bone remodeling and osseointegration

Surgical failure, mainly caused by loosening implants, causes great mental and physical trauma to patients.

BMSCs protect against liver injury via suppressing hepatocyte apoptosis and activating TGF-β1/Bax singling pathway

Many factors cause liver injury, including chronic consumption of alcohol, irregular use of drugs, excessive levels of arsenic in water. This study aims to investigate role of bone marrow-derived mesenchymal stem cells (BMSCs) in liver injury recovery and to explore mechanism. BMSCs and primary hepatocytes were isolated, cultured and identified. Hepatocyte model and hepatic fibrosis (HF) model were established using carbon tetrachloride (CCL-4). The role of BMSCs were investigated in both in vitro and in vivo levels. Cell proliferation was examined using MTT assay. Transforming growth factor-β1 (TGF-β1), Bcl-2 and Bax expression were detected using western blot and real-time PCR, respectively. Results indicated that BMSCs and primary hepatocytes were successfully isolated and identified, and hepatocyte model was successfully established. BMSCs and HGF treatment enhance viability of normal hepatocytes and hepatocyte injury model. Cell viability in BMSCs treatment and Bax-1 inhibitor treatment group was higher significantly compared to normal hepatocyte control and injury hepatocyte model, respectively (P<0.05). Bax-1 expression was significantly lower and Bcl-2 was significantly higher in Bax-1 inhibitor treatment and BMSCs treatment group compared to normal hepatocyte control (normal rats) and injury hepatocyte model (HF model), respectively (P<0.05). BMSCs significantly decreased ALT and AST levels compared to Saline group (P<0.05). In conclusion, function of BMSCs in liver injury was triggered by inhibiting hepatocyte apoptosis and leading cell proliferation through TGF-β1/Bax singling pathway. Our study proved protective role of BMSCs against liver injury via TGF-β1/Bax pathway, which would enrich application of BMSC in clinical.

MicroRNA-21 promotes bone mesenchymal stem cells migration in vitro by activating PI3K/Akt/MMPs pathway

MicroRNA-21 (miR-21) contributes to anti-apoptosis in bone marrow mesenchymal stem cells (BMSC), but its role in the migration of BMSCs remains vague. The aim of this study was to determine the possible effect of miR-21 on regulating BMSCs directional migration and the expression of MMP-2/MMP-9 in BMSCs in vitro. BMSCs were successfully infected with miR-21-up lentivirus. Cell migration using Transwell assay indicated that upregulated expression of miR-21 could significantly promote BMSCs migration. Western blot analysis indicated that miR-21 significantly upregulated the expression of MMP-2 and MMP-9, which were related to metastasis-associated genes. GM6001, the specific MMPs inhibitor, abrogated the upregulated expression of MMP-2/MMP-9 and abolished the positive effect of miR-21 on promoting BMSCs migration. Meanwhile, miR-21 significantly enhanced Akt phosphorylation, as measured by Western blot analysis. LY294002, an inhibitor of Akt activation, abrogated the phosphorylation of Akt and abolished the positive effect of miR-21 on promoting BMSCs migration and upregulating MMP-2/MMP-9 expression. These results suggest that miR-21 contributes to BMSCs migration by upregulating MMP-2/MMP-9, potentially via the PI3K/Akt pathway.

Overexpression of miR-21 in stem cells improves ovarian structure and function in rats with chemotherapy-induced ovarian damage by targeting PDCD4 and PTEN to inhibit granulosa cell apoptosis

BACKGROUND

Chemotherapy-induced premature ovarian failure (POF) is a severe complication affecting tumor patients at a childbearing age. Mesenchymal stem cells (MSCs) can partially restore the ovarian structure and function damaged by chemotherapy. miR-21 is a microRNA that can regulate cell apoptosis. This study discusses the repair effect and mechanism of MSCs overexpressing miR-21 on chemotherapy-induced POF.

METHODS

Rat MSCs and granulosa cells (GCs) were isolated in vitro. MSCs were transfected with miR-21 lentiviral vector (LV-miR-21) to obtain MSCs stably expressing miR-21 (miR-21-MSCs). The microenvironment of an ovary receiving chemotherapy was mimicked by adding phosphamide mustard (PM) into the cellular culture medium. The apoptosis rate and the mRNA and protein expression of target genes PTEN and PDCD4 were detected in MSCs. Apoptosis was induced by adding PM into the culture medium for GCs, which were cocultured with miR-21-MSCs. The apoptosis rate and the mRNA and protein expression of PTEN and PDCD4 were detected. The chemotherapy-induced POF model was built into rats by intraperitoneal cyclophosphamide injection. miR-21-MSCs were transplanted into the bilateral ovary. The rats were sacrificed at 15, 30, 45, and 60 days after the last injection. The ovarian weights, follicle count, estrous cycle, and sex hormone levels (estradiol (E2) and follicle-stimulating hormone (FSH)) were detected. Apoptosis of GCs was determined by TUNEL assay. The miR-21 and mRNA and protein expression of PTEN and PDCD4 were determined.

RESULTS

The apoptosis decreased in MSCs transfected with miR-21. The mRNA and protein expression of target genes PTEN and PDCD4 was downregulated. GCs cocultured with miR-21-MSCs showed a decreased apoptosis, an upregulation of miR-21, and a downregulation of PTEN and PDCD4. Following the injection of miR-21-MSCs, the ovarian weight and follicle counts increased; E₂ levels increased while FSH levels decreased, with less severe apoptosis of GCs. The miR-21 expression in the ovaries was upregulated, while the mRNA expression and protein expression of PTEN and PDCD4 were downregulated.

CONCLUSIONS

Overexpression of miR-21 in MSCs promoted efficacy against chemotherapy-induced POF and its improvement of the repair effect was related to the inhibition of GC apoptosis by targeting PTEN and PDCD4.

miR-21 increases c-kit+ cardiac stem cell proliferation in vitro through PTEN/PI3K/Akt signaling

The low survival rate of cardiac stem cells (CSCs) in the ischemic myocardium is one of the obstacles in ischemic cardiomyopathy cell therapy. The MicroRNA (miR)-21 and one of its target protein, the tensin homolog deleted on chromosome ten (PTEN), contributes to the proliferation of many kinds of tissues and cell types. It is reported that miR-21 promotes proliferation through PTEN/PI3K/Akt pathway, but its effects on c-kit⁺ CSC remain unclear. The authors hypothesized that miR-21 promotes the proliferation in c-kit ⁺ CSC, and evaluated the involvement of PTEN/PI3K/Akt pathway in vitro. miR-21 up-regulation with miR-21 efficiently mimics accelerated cell viability and proliferation in c-kit ⁺ CSC, which was evidenced by the CCK-8, EdU and cell cycle analyses. In addition, the over-expression of miR-21 in c-kit ⁺ CSCs notably down-regulated the protein expression of PTEN although the mRNA level of PTEN showed little change. Gain-of-function of miR-21 also increased the phosphor-Akt (p-Akt) level. Phen, the selective inhibitor of PTEN, reproduced the pro-proliferation effects of miR-21, while PI3K inhibitor, LY294002, totally attenuated the pro-survival effect of miR-21. These results indicate that miR-21 is efficient in promoting proliferation in c-kit⁺ CSCs, which is contributed by the PTEN/PI3K/Akt pathway. miR-21 holds the potential to facilitate CSC therapy in ischemic myocardium.

miR-21 Reduces Hydrogen Peroxide-Induced Apoptosis in c-kit+ Cardiac Stem Cells In Vitro through PTEN/PI3K/Akt Signaling

The low survival rate of cardiac stem cells (CSCs) in the infarcted myocardium hampers cell therapy for ischemic cardiomyopathy. MicroRNA-21 (miR-21) and one of its target proteins, PTEN, contribute to the survival and proliferation of many cell types, but their prosurvival effects in c-kit⁺ CSC remain unclear. Thus, we hypothesized that miR-21 reduces hydrogen peroxide- (H₂O₂-) induced apoptosis in c-kit⁺ CSC and estimated the contribution of PTEN/PI3K/Akt signaling to this oxidative circumstance. miR-21 mimics efficiently reduced H₂O₂-induced apoptosis in c-kit⁺ CSC, as evidenced by the downregulation of the proapoptosis proteins caspase-3 and Bax and upregulation of the antiapoptotic Bcl-2. In addition, the gain of function of miR-21 in c-kit⁺ CSC downregulated the protein level of PTEN although its mRNA level changed slightly; in the meantime, miR-21 overexpression also increased phospho-Akt (p-Akt). The antiapoptotic effects of miR-21 were comparable with Phen (bpV), the selective inhibitor of PTEN, while miR-21 inhibitor or PI3K's inhibitor LY294002 efficiently attenuated the antiapoptotic effect of miR-21. Taken together, these results indicate that the anti-H₂O₂-induced apoptosis effect of miR-21 in c-kit⁺ CSC is contributed by PTEN/PI3K/Akt signaling. miR-21 could be a potential molecule to facilitate the c-kit⁺ CSC therapy in ischemic myocardium.