EGCG ameliorates the hypoxia-induced apoptosis and osteogenic differentiation reduction of mesenchymal stem cells via upregulating miR-210

Natural compounds and mesenchymal stem cells: implications for inflammatory-impaired tissue regeneration

Inflammation is a common and important pathological process occurring in any part of the body and relating to a variety of diseases. Effective tissue repair is critical for the survival of impaired organisms. Considering the side effects of the currently used anti-inflammatory medications, new therapeutic agents are urgently needed for the improvement of regenerative capacities of inflammatory-impaired tissues. Mesenchymal stromal stem/progenitor cells (MSCs) are characterized by the capabilities of self-renewal and multipotent differentiation and exhibit immunomodulatory capacity. Due to the ability to modulate inflammatory phenotypes and immune responses, MSCs have been considered as a potential alternative therapy for autoimmune and inflammatory diseases. Natural compounds (NCs) are complex small multiple-target molecules mostly derived from plants and microorganisms, exhibiting therapeutic effects in many disorders, such as osteoporosis, diabetes, cancer, and inflammatory/autoimmune diseases. Recently, increasing studies focused on the prominent effects of NCs on MSCs, including the regulation of cell survival and inflammatory response, as well as osteogenic/adipogenic differentiation capacities, which indicate the roles of NCs on MSC-based cytotherapy in several inflammatory diseases. Their therapeutic effects and fewer side effects in numerous physiological processes, compared to chemosynthetic drugs, made them to be a new therapeutic avenue combined with MSCs for impaired tissue regeneration. Here we summarize the current understanding of the influence of NCs on MSCs and related downstream signaling pathways, specifically in pathological inflammatory conditions. In addition, the emerging concepts through the combination of NCs and MSCs to expand the therapeutic perspectives are highlighted. A promising MSC source from oral/dental tissues is also discussed, with a remarkable potential for MSC-based therapy in future clinical applications.

The Emerging Role of Non-Coding RNAs in Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells

Autologous bone marrow-derived mesenchymal stem cells (BMSCs) are more easily available and frequently used for bone regeneration in clinics. Osteogenic differentiation of BMSCs involves complex regulatory networks affecting bone formation phenomena. Non-coding RNAs (ncRNAs) refer to RNAs that do not encode proteins, mainly including microRNAs, long non-coding RNAs, circular RNAs, piwi-interacting RNAs, transfer RNA-derived small RNAs, etc. Recent in vitro and in vivo studies had revealed the regulatory role of ncRNAs in osteogenic differentiation of BMSCs. NcRNAs had both stimulatory and inhibitory effects on osteogenic differentiation of BMSCs. During the physiological condition, osteo-stimulatory ncRNAs are upregulated and osteo-inhibitory ncRNAs are downregulated. The opposite effects might occur during bone degenerative disease conditions. Intracellular ncRNAs and ncRNAs from neighboring cells delivered via exosomes participate in the regulatory process of osteogenic differentiation of BMSCs. In this review, we summarize the recent advances in the regulatory role of ncRNAs on osteogenic differentiation of BMSCs during physiological and pathological conditions. We also discuss the prospects of the application of modulation of ncRNAs function in BMSCs to promote bone tissue regeneration in clinics.

The Role of Flavonoids in the Osteogenic Differentiation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) play an important role in developing bone tissue engineered constructs due to their osteogenic and chondrogenic differentiation potential. MSC-based tissue engineered constructs are generally considered a safe procedure, however, the long-term results obtained up to now are far from satisfactory. The main causes of these therapeutic limitations are inefficient homing, engraftment, and directional differentiation. Flavonoids are a secondary metabolite, widely existed in nature and have many biological activities. For a long time, researchers have confirmed the anti-osteoporosis effect of flavonoids through in vitro cell experiments, animal studies. In recent years the regulatory effects of flavonoids on mesenchymal stem cells (MSCs) differentiation have been received increasingly attention. Recent studies revealed flavonoids possess the ability to modulate self-renewal and differentiation potential of MSCs. In order to facilitate further research on MSCs osteogenic differentiation of flavonoids, we surveyed the literature published on the use of flavonoids in osteogenic differentiation of MSCs, and summarized their pharmacological activities as well as the underlying mechanisms, aimed to explore their promising therapeutic application in bone disorders and bone tissue engineered constructs.

Hypoxia-Induced miR-210 Overexpression Promotes the Differentiation of Human-Induced Pluripotent Stem Cells to Hepatocyte-Like Cells on Random Nanofiber Poly-L-Lactic Acid/Poly (ε-Caprolactone) Scaffolds

An alternative treatment to liver transplantation includes the use of differentiated stem cells. Hypoxia has been shown to endow human-induced pluripotent stem cells (hiPSCs) with enhanced hepatic differentiation. We have investigated a new strategy for hepatocyte differentiation from hiPSCs using a three-step differentiation protocol with lentiviral overexpression of hypoxia-microRNA-210 of cells grown on a hybrid scaffold. We analyzed the transduction of the miR-210 lentiviral and definitive endoderm and pluripotency gene markers, including SRY-box 17 (SOX17), forkhead box A2 (FOXA2), and octamer-binding transcription factor 4 (OCT-4) by Real-Time PCR and fluorescent microscope. The scanning electron microscopy (SEM) examined the 3D cell morphological changes. Immunocytochemistry staining was used together with assays for aspartate aminotransferase, alanine aminotransferase, and urea secretion to analyze hepatocyte biomarkers and functional markers consisting of α-fetoprotein (AFP), low-density lipoprotein (LDL) uptake, fat accumulation, and glycogen. The flow cytometry analyzed the generation of reactive oxygen species (ROS). Compared to cells transfected with the blank lentiviral vectors as a control, overexpressing miR-210 was at higher levels in hiPSCs. The expression of endodermal genes and glycogen synthesis significantly increased in the differentiated lentiviral miR-210 cells without any differences regarding lipid storage level. Additionally, cells containing miR-210 showed a greater expression of ALB, LDL, AST, ALT, urea, and insignificant lower AFP and ROS levels after 18 days. However, SEM showed no significant differences between cells under the differentiation process and controls. In conclusion, the differentiation of hiPSCs to hepatocyte-like cells under hypoxia miR-210 may be a suitable method for cell therapy and regenerative medicine.

Size-controlled human adipose-derived stem cell spheroids hybridized with single-segmented nanofibers and their effect on viability and stem cell differentiation

BACKGROUND

Fabrication of three-dimensional stem cell spheroids have been studied to improve stem cell function, but the hypoxic core and limited penetration of nutrients and signaling cues to the interior of the spheroid were challenges. The incorporation of polymers such as silica and gelatin in spheroids resulted in relatively relaxed assembly of composite spheroids, and enhancing transport of nutrient and biological gas. However, because of the low surface area between cells and since the polymers were heterogeneously distributed throughout the spheroid, these polymers cannot increase the cell to extracellular matrix interactions needed to support differentiation.

METHODS

We developed the stem cell spheroids that incorporate poly(ι-lactic acid) single-segmented fibers synthesized by electrospinning and physical and chemical fragmentation. The proper mixing ratio was 2000 cells/μg fibers (average length of the fibers was 50 μm - 100 μm). The SFs were coated with polydopamine to increase cell binding affinity and to synthesize various-sized spheroids. The function of spheroids was investigated by in vitro analysis depending on their sizes. For statistical analysis, Graphpad Prism 5 software (San Diego, CA, USA) was used to perform one-way analysis of variance ANOVA with Tukey's honest significant difference test and a Student's t-test (for two variables) (P < 0.05).

RESULTS

Spheroids of different sizes were created by modulating the amount of cells and fibers (0.063 mm2-0.322 mm2). The fibers in the spheroid were homogenously distributed and increased cell viability, while cell-only spheroids showed a loss of DNA contents, internal degradation, and many apoptotic signals. Furthermore, we investigated stemness and various functions of various-sized fiber-incorporated spheroids. In conclusion, the spheroid with the largest size showed the greatest release of angiogenic factors (released VEGF: 0.111 ± 0.004 pg/ng DNA), while the smallest size showed greater effects of osteogenic differentiation (mineralized calcium: 18.099 ± 0.271 ng/ng DNA).

CONCLUSION

The spheroids incorporating polydopamine coated single-segmented fibers showed enhanced viability regardless of sizes and increased their functionality by regulating the size of spheroids which may be used for various tissue reconstruction and therapeutic applications.

Osteoprotective Roles of Green Tea Catechins

Osteoporosis is the second most common disease only secondary to cardiovascular disease, with the risk of fracture increasing with age. Osteoporosis is caused by an imbalance between osteoblastogenesis and osteoclastogenesis processes. Osteoclastogenesis may be enhanced, osteoblastogenesis may be reduced, or both may be evident. Inflammation and high reactive oxygen enhance osteoclastogenesis while reducing osteoblastogenesis by inducing osteoblast apoptosis and suppressing osteoblastic proliferation and differentiation. Catechins, the main polyphenols found in green tea with potent anti-oxidant and anti-inflammatory properties, can counteract the deleterious effects of the imbalance of osteoblastogenesis and osteoclastogenesis caused by osteoporosis. Green tea catechins can attenuate osteoclastogenesis by enhancing apoptosis of osteoclasts, hampering osteoclastogenesis, and prohibiting bone resorption in vitro. Catechin effects can be directly exerted on pre-osteoclasts/osteoclasts or indirectly exerted via the modulation of mesenchymal stem cells (MSCs)/stromal cell regulation of pre-osteoclasts through activation of the nuclear factor kB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system. Catechins also can enhance osteoblastogenesis by enhancing osteogenic differentiation of MSCs and increasing osteoblastic survival, proliferation, differentiation, and mineralization. The in vitro effects of catechins on osteogenesis have been confirmed in several animal models, as well as in epidemiological observational studies on human subjects. Even though randomized control trials have not shown that catechins provide anti-fracture efficacy, safety data in the trials are promising. A large-scale, placebo-controlled, long-term randomized trial with a tea regimen intervention of optimal duration is required to determine anti-fracture efficacy.

Regulation of osteogenesis via miR-101-3p in mesenchymal stem cells by human gingival fibroblasts

INTRODUCTION

Mesenchymal stem cells (MSCs) can differentiate into various types of cells and can thus be used for periodontal regenerative therapy. However, the mechanism of differentiation is still unclear. Transplanted MSCs are, via their transcription factors or microRNAs (miRNAs), affected by periodontal cells with direct contact or secretion of humoral factors. Therefore, transplanted MSCs are regulated by humoral factors from human gingival fibroblasts (HGF). Moreover, insulin-like growth factor (IGF)-1 is secreted from HGF and regulates periodontal regeneration. To clarify the regulatory mechanism for MSC differentiation by humoral factors from HGF, we identified key genes, specifically miRNAs, involved in this process, and determined their function in MSC differentiation.

MATERIALS AND METHODS

Mesenchymal stem cells were indirectly co-cultured with HGF in osteogenic or growth conditions and then evaluated for osteogenesis, undifferentiated MSC markers, and characteristic miRNAs. MSCs had their miRNA expression levels adjusted or were challenged with IGF-1 during osteogenesis, or both of which were performed, and then, MSCs were evaluated for osteogenesis or undifferentiated MSC markers.

RESULTS

Mesenchymal stem cells co-cultured with HGF showed suppression of osteogenesis and characteristic expression of ETV1, an undifferentiated MSC marker, as well as miR-101-3p. Over-expression of miR-101-3p regulated osteogenesis and ETV1 expression as well as indirect co-culture with HGF. IGF-1 induced miR-101-3p and ETV1 expression. However, IGF-1 did not suppress osteogenesis.

CONCLUSIONS

Humoral factors from HGF suppressed osteogenesis in MSCs. The effect was regulated by miRNAs and undifferentiated MSC markers. miR-101-3p and ETV1 were the key factors and were regulated by IGF-1.

Green Tea Catechin (-)-Epigallocatechin-3-Gallate (EGCG) Facilitates Fracture Healing

Green tea drinking can ameliorate postmenopausal osteoporosis by increasing the bone mineral density. (-)-Epigallocatechin-3-gallate (EGCG), the abundant and active compound of tea catechin, was proven to be able to reduce bone loss and ameliorate microarchitecture in female ovariectomized rats. EGCG can also enhance the osteogenic differentiation of murine bone marrow mesenchymal stem cells and inhibit the osteoclastogenesis in RAW264.7 cells by modulation of the receptor activator of nuclear factor-kB (RANK)/RANK ligand (RANKL)/osteoprotegrin (OPG) (RANK/RANKL/OPG) pathway. Our previous study also found that EGCG can promote bone defect healing in the distal femur partially via bone morphogenetic protein-2 (BMP-2). Considering the osteoinduction property of BMP-2, we hypothesized that EGCG could accelerate the bone healing process with an increased expression of BMP-2. In this manuscript, we studied whether the local use of EGCG can facilitate tibial fracture healing. Fifty-six 4-month-old rats were randomly assigned to two groups after being weight-matched: a control group with vehicle treatment (Ctrl) and a study group with 10 µmol/L, 40 µL, EGCG treatment (EGCG). Two days after the operation, the rats were treated daily with EGCG or vehicle by percutaneous local injection for 2 weeks. The application of EGCG enhanced callus formation by increasing the bone volume and subsequently improved the mechanical properties of the tibial bone, including the maximal load, break load, stiffness, and Young’s modulus. The results of the histology and BMP-2 immunohistochemistry staining showed that EGCG treatment accelerated the bone matrix formation and produced a stronger expression of BMP-2. Taken together, this study for the first time demonstrated that local treatment of EGCG can accelerate the fracture healing process at least partly via BMP-2.

Epigallocatechin-3-gallate protects Wharton's jelly derived mesenchymal stem cells against in vitro heat stress

The deteriorating effects of heat stress abrogate the therapeutic implications of human Wharton's jelly derived mesenchymal stem cells (hWJMSCs) transplanted in burn wounds. Topically applied green tea extract comprising epigallocatechin-3-gallate (EGCG) is known to repair burn wounds. Here, we investigated the protective role of EGCG priming of hWJMSCs against heat-induced stress in vitro along with the involved underlying mechanism. EGCG ameliorated heat-induced injuries as demonstrated by significantly improved cell morphology, viability, triggered cell migration and enhanced expression of heat shock proteins. In addition, decreased lactate dehydrogenase release and reduced percentage of senescent and apoptotic cells were observed. EGCG priming alleviated the detrimental effects of thermal stress in hWJMSCs as observed by significant down-regulation in expression of BCL2 associated X (BAX), interleukin 6 (IL6), and interleukin 1 beta (IL1β) genes, while proliferating cell nuclear antigen (PCNA), BCL2 like 1 (BCL2L1), vascular endothelial growth factor (VEGF), transforming growth factor beta 1 (TGFβ1), hepatocyte growth factor (HGF) and interleukin 4 (IL4) genes were up-regulated. Accompanying gene expression data, EGCG primed cells exposed to heat stress also exhibited remarkably increased secretion of VEGF, HGF, epidermal growth factor (EGF), stromal-derived factor 1 (SDF1) proteins while the reduced release of IL-6, and tumor necrosis factor-alpha (TNF-α) proteins. Further, synergistic activation of extracellular-signal-regulated kinase (ERK) and protein kinase B (PKB/AKT) proteins was observed. These findings suggest that EGCG priming might enhance the therapeutic efficacy of hWJMSCs in the burnt tissue through regulation of ERK and AKT signaling pathways, and improved cellular responses.

(-)-Epigallocatechin-3-gallate (EGCG) enhances healing of femoral bone defect

BACKGROUND

Previously, we found that (-)-epigallocatechin-3-gallate (EGCG) enhanced osteogenic differentiation of murine bone marrow mesenchymal stem cells by increasing the mRNA expression of osteogenesis-related genes, alkaline phosphatase activity and eventually mineralization. We further found EGCG supplementation preserved bone mass and microarchitecture in female rats during estrogen deficiency in the proximal tibia and lumbar spine at least in part by increasing bone morphogenetic protein-2 (BMP2). BMP2 can enhance de novo bone formation.

PURPOSE

In this study, we evaluate the effect of local EGCG application in de novo bone formation in bone defect healing.

METHODS

Twenty-four rats aged 4 months were weight-matched and randomly allocated to 2 groups: defect control with vehicle treatment (control) and defect with 10 µM EGCG treatment (EGCG). Daily vehicle and EGCG were applied locally by percutaneous local injection 2 days after defect creation for 2 weeks. Four weeks after treatment, animals were sacrificed for micro-computed tomography (μ-CT) and biomechanical analysis.

RESULTS

Local EGCG at femoral defect can enhance de novo bone formation by increasing bone volume and subsequently improve mechanical properties including max load, break point, stiffness, area under the max load curve, area under the break point curve and ultimate stress.

CONCLUSIONS

Local EGCG may enhance bone defect healing via at least partly by the de novo bone formation of BMP-2.

Upregulation of miR-210 promotes differentiation of mesenchymal stem cells (MSCs) into osteoblasts

Numerous studies indicated that microRNAs are critical in the regulation of cellular differentiation, by controlling the expression of underlying genes. The aim of this study was to investigate the effect of miR-210 upregulation on differentiation of human umbilical cord blood (HUCB)-derived mesenchymal stem cells (MSCs) into osteoblasts. MSCs were isolated from HUCB and confirmed by their adipogenic/osteogenic differentiation and flow cytometric analysis of surface markers. Pre-miR-210 was amplified from human DNA, digested and ligated with plenti-III-mir-green fluorescent protein (GFP) vector, and cloned in STBL4 bacteria. After confirmation with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), the plenti-III-GFP segment bearing pre-miR-210 was transfected into MSCs by electroporation. Two control vectors, pmaxGFP and Scramble, were transfected separately into MSCs. The expression of miR-210 and genes related to osteoblast differentiation, i.e., runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP) and osteocalcin gene, in the three groups of transfected MSCs was analyzed 0, 7, 14, and 21 days of transfection by quantitative reverse transcription PCR (qRT-PCR). Overexpression of miR-210 was observed in MSCs transfected with miR-210-bearing plasmid, and this was significantly different compared to Scramble group (p < 0.05). Significantly increased expression of Runx2 (at day 7 and 14), ALP and osteocalcin genes (at all time points for both genes) was observed in MSCs with miR-210-bearing plasmid compared to controls. Overall, the overexpression of miR-210 in MSCs led to MSC differentiation into osteoblasts, most probably by upregulating the Runx2, ALP, and osteocalcin genes at different stages of cell differentiation. Our study confirms the potential of miRNAs in developing novel therapeutic strategies that could target regulatory mechanisms of cellular differentiation in various disease states.

Preparation and in vitro evaluation of novel cross-linked chondroitin sulphate nanoparticles by aluminium ions for encapsulation of green tea flavonoids

Chondroitin sulphate is a sulphated glycosaminoglycan biopolymer composed over 100 individual sugars. Chondroitin sulphate nanoparticles (NPs) loaded with catechin were prepared by an ionic gelation method using AlCl₃ and optimised for polymer and cross-linking agent concentration, curing time and stirring speed. Zeta potential, particle size, loading efficiency, and release efficiency over 24 h (RE₂₄%) were evaluated. The surface morphology of NPs was investigated by scanning electron microscopy and their thermal behaviour by differential scanning calorimetric. Antioxidant effect of NPs was determined by chelating activity of iron ions. The cell viability of mesenchymal stem cells was determined by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide assay and the calcification of osteoblasts was studied by Alizarin red staining. The optimised NPs showed particle size of 176 nm, zeta potential of -20.8 mV, loading efficiency of 93.3% and RE₂₄% of 80.6%. The chatechin loaded chondroitin sulphate NPs showed 70-fold more antioxidant activity, 3-fold proliferation effect and higher calcium precipitation in osteoblasts than free catechin.

Potential Non-neoplastic Applications for Polyphenols in Stem Cell Utilization

While polyphenols may have important effects on pluripotential stem cells that make them noteworthy as potential antineoplastic agents, their action on stem cells may portend other health benefits, such as treatments for cardiovascular and neurocognitive disorders. Resveratrol, the beststudied polyphenol, has been found to enable stem cells to differentiate into cardiomyocytes, neurons, osteocytes, and pancreatic beta cells, as well as facilitating augmentation of stem cell populations and protecting them from toxic injury. Curcumin protects mesenchymal stem cells from toxicity, and prevents them from facilitating chondrocytic hypertrophy. Quercetin enabled osteocytic and pancreatic beta cell differentiation, and protected neuronal stem cells from injury. Epigallocatechin gallate prevented damage to osteocyte precursors and averted differentiation into undesirable adipocytes. Genistein facilitated osteogenesis while preventing adipogenesis. Several other polyphenols, daidzein, caffeic and chlorogenic acid, kaempferol, and piceatannol, protect stems cells from reactive oxygen species and foster stem cells differentiation away from adipocytic and toward osteocytic lineages. Further research should better elucidate the pharmacokinetic profiles of each polyphenol, explore novel delivery systems, and expand investigation beyond rodent models to additional species.

Functional reconstruction of critical-sized load-bearing bone defects using a Sclerostin-targeting miR-210-3p-based construct to enhance osteogenic activity

A considerable amount of research has focused on improving regenerative therapy strategies for repairing defects in load-bearing bones. The enhancement of tissue regeneration with microRNAs (miRNAs) is being developed because miRNAs can simultaneously regulate multiple signaling pathways in an endogenous manner. In this study, we developed a miR-210-based bone repair strategy. We identified a miRNA (miR-210-3p) that can simultaneously up-regulate the expression of multiple key osteogenic genes in vitro. This process resulted in enhanced bone formation in a subcutaneous mouse model with a miR-210-3p/poly-l-lactic acid (PLLA)/bone marrow-derived stem cell (BMSC) construct. Furthermore, we constructed a model of critical-sized load-bearing bone defects and implanted a miR-210-3p/β-tricalcium phosphate (β-TCP)/bone mesenchymal stem cell (BMSC) construct into the defect. We found that the load-bearing defect was almost fully repaired using the miR-210-3p construct. We also identified a new mechanism by which miR-210-3p regulates Sclerostin protein levels. This miRNA-based strategy may yield novel therapeutic methods for the treatment of regenerative defects in vital load-bearing bones by utilizing miRNA therapy for tissue engineering.

STATEMENT OF SIGNIFICANCE

The destroyed maxillofacial bone reconstruction is still a real challenge for maxillofacial surgeon, due to that functional bone reconstruction involved load-bearing. Base on the above problem, this paper developed a novel miR-210-3p/β-tricalcium phosphate (TCP)/bone marrow-derived stem cell (BMSC) construct (miR-210-3p/β-TCP/BMSCs), which lead to functional reconstruction of critical-size mandible bone defect. We found that the load-bearing defect was almost fully repaired using the miR-210-3p construct. In addition, we also found the mechanism of how the delivered microRNA activated the signaling pathways of endogenous stem cells, leading to the defect regeneration. This miRNA-based strategy can be used to regenerate defects in vital load-bearing bones, thus addressing a critical challenge in regenerative medicine by utilizing miRNA therapy for tissue engineering.

The yerba mate intake has a neutral effect on bone: A case-control study in postmenopausal women

Nutritional factors have been associated with osteoporosis and fractures. The intake of coffee may increase the risk of fracture whereas the intake of black and green tea is associated with its reduction. Recently, consumption of yerba mate was associated with increased bone mineral density in postmenopausal women. Nonetheless, its influence on fracture is not known. The aim of this study was to evaluate the effect of yerba mate tea intake on fractures, bone markers, calcium homeostasis, and oxidative stress in postmenopausal women. A case-control study was carried out in South Brazil, 46 women with fractures and 49 controls completed the study. There was no significant difference between the frequency of fractures in women who drank mate tea and women who did not (48.3% vs. 48.5%, p = .99). Moreover, there was no significant difference concerning the serum levels of total calcium, phosphorus, PTH, vitamin D, P1NP, and CTX in the subjects with the history of yerba mate use when compared to controls. Higher serum levels of NOx were found in women who drank the yerba mate infusion. In conclusion, the yerba mate intake is not associated with fracture, and it appears to have a neutral effect on the bone metabolism.

MicroRNA-210 is increased and it is required for dedifferentiation of osteosarcoma cell line

Osteosarcoma (OS) is the most common malignant bone tumor and is prevalent in adolescents. In clinical studies, miR-210 has been reported to be tightly correlated to the poor prognosis of OS. Nevertheless, its roles in OS have not been fully elucidated. In view of the central role played by OS stem cells (OSCs) in the malignant progression of OS, this study investigated the influence of miR-210 on the formation of OSCs. Our previous findings suggested that the microenvironment of bone, abundant TGF-β1 and hypoxia, could induce OS cells to dedifferentiate into OSCs. In this study, we found that miR-210 participated in the dedifferentiation of OS cells into OSCs, and inhibiting it significantly suppressed the formation of OSCs. Further results suggested that miR-210 promoted the expression of TGF-β1 and its downstream effectors Snail1 and Slug which were highly elevated in the process of OS dedifferentiation. Additionally, the target gene of miR-210 was also investigated. It was found that NFIC was significantly reduced by miR-210 treatment and also during OS dedifferentiation. Therefore, this study suggested that miR-210 promoted OS cells dedifferentiation and uncovered its role in the malignant progress of OS.

Precise Regulation of miR-210 Is Critical for the Cellular Homeostasis Maintenance and Transplantation Efficacy Enhancement of Mesenchymal Stem Cells in Acute Liver Failure Therapy

Stem cell transplantation is a promising clinical strategy to cure acute liver failure. However, a low cell survival ratio after transplantation significantly impairs its therapeutic efficacy. This is partly due to insufficient resistance of transplanted stem cells to severe oxidative and inflammatory stress at the injury sites. In the current study, we demonstrated that a small molecule zeaxanthin dipalmitate (ZD) could enhance the defensive abilities against adverse stresses of human adipose-derived mesenchymal stem cells (hADMSCs) in vitro and increase their therapeutic outcomes of acute liver failure after transplantation in vivo. Treatment with ZD dramatically improved cell survival and suppressed apoptosis, inflammation, and reactive oxygen species (ROS) production of hADMSCs through the PKC/Raf-1/MAPK/NF-κB pathway to maintain a reasonably high expression level of microRNA-210 (miR-210). The regulation loop between miR-210 and cellular/mitochondrial ROS production was found to be linked by the ROS inhibitor iron-sulfur cluster assembly proteins (ISCU). Pretreatment with ZD and stable knockdown of miR-210 significantly improved and impaired the stem cell transplantation efficacy through the alteration of hepatic cell expansion and injury amelioration, respectively. Vehicle treatment with ZD did not pose any adverse effect on cell homeostasis or healthy animal. In conclusion, elevating endogenous antioxidant level of hADMSCs with ZD significantly enhances their hepatic tissue-repairing capabilities. Maintenance of a physiological level of miR-210 is critical for hADMSC homeostasis.