MSM enhances GH signaling via the Jak2/STAT5b pathway in osteoblast-like cells and osteoblast differentiation through the activation of STAT5b in MSCs

Methylsulfonylmethane Improves Knee Quality of Life in Participants with Mild Knee Pain: A Randomized, Double-Blind, Placebo-Controlled Trial

Methylsulfonylmethane (MSM) is a food ingredient present in small amounts in many foods, and its anti-inflammatory effects have been reported. We conducted a randomized, double-blind, placebo-controlled trial of oral consumption of MSM on mild pain of the knee joint in healthy Japanese participants. A total of 88 participants were enrolled in this study and randomly assigned to MSM consumption (n = 44) and placebo control (n = 44) groups. Both groups of participants took 10 tablets, each containing 200 mg MSM or lactose, per day for 12 weeks. The primary outcome of this study was measured values of the total score of the Japanese Knee Osteoarthritis Measure (JKOM) at 12 weeks after the test sample consumption. Safety evaluation was performed through physical examination, urine analysis, peripheral blood test, and medical interview. The total scores at 12 weeks in the MSM and placebo groups as the primary outcome were significantly different (p = 0.046). The health condition of JKOM also improved after MSM consumption (p = 0.032). The questionnaire results also suggested improvement in the knee and systemic health. This study indicated that MSM oral consumption improved both knee and systemic health conditions in healthy participants who experienced mild pain in the knee joint.

Additive Effects of Dietary Supplementation with Zeolite and Methyl-Sulfonyl-Methane on Growth Performance and Interleukin Levels of Broiler Chickens

Silicate minerals are common additives in poultry feed. To assess their effects, we added zeolite (ZEO) and methyl-sulfonyl-methane (MSM) to broiler chicken diets. A total of 960 one-day-old Ross broiler chicks were randomly divided into four dietary groups with six replicates. Each broiler was maintained until it reached 35 days of age. A completely randomized 2 × 2 experimental design was used, with two ZEO (0 and 1.0%) and two MSM (0 and 0.10%) levels. We observed an additive effect (P<0.05) on interleukin-2 (IL-2) concentrations in broiler bursa and serum when both ZEO and MSM were present. Both ZEO or MSM produced significant (P<0.05) increases in body weight, weight gain, and feed intake. Both increased IL-2 and IL-6 levels in the bursa and serum. Neither affected the serum concentrations of albumin, AST, cholesterol, HDL cholesterol, glucose, total protein, or triglycerides. In summary, these results support supplementation with ZEO and MSM in broiler diets, both separately and in combination.

Sustained Delivery of Methylsulfonylmethane from Biodegradable Scaffolds Enhances Efficient Bone Regeneration

Introduction

As a popular dietary supplement containing sulfur compound, methylsulfonylmethane (MSM) has been widely used as an alternative oral medicine to relieve joint pain, reduce inflammation and promote collagen protein synthesis. However, it is rarely used in developing bioactive scaffolds in bone tissue engineering.

Methods

Three-dimensional (3D) hydroxyapatite/poly (lactide-co-glycolide) (HA/PLGA) porous scaffolds with different doping levels of MSM were prepared using the phase separation method. MSM loading efficiency, in vitro drug release as well as the biological activity of MSM-loaded scaffolds were investigated by incubating mouse pre-osteoblasts (MC3T3-E1) in the uniform and interconnected porous scaffolds.

Results

Sustained release of MSM from the scaffolds was observed, and the total MSM release from 1% and 10% MSM/HA/PLGA scaffolds within 16 days was up to 64.9% and 68.2%, respectively. Cell viability, proliferation, and alkaline phosphatase (ALP) activity were significantly promoted by incorporating 0.1% of MSM in the scaffolds. In vivo bone formation ability was significantly enhanced for 1% MSM/HA/PLGA scaffolds indicated by the repair of rabbit radius defects which might be affected by a stimulated release of MSM by enzyme systems in vivo.

Discussion

Finding from this study revealed that the incorporation of MSM would be effective in improving the osteogenesis activity of the HA/PLGA porous scaffolds.

Cell-Based Double-Screening Method to Identify a Reliable Candidate for Osteogenesis-Targeting Compounds

Small-molecule compounds strongly affecting osteogenesis can form the basis of effective therapeutic strategies in bone regenerative medicine. A cell-based high-throughput screening system might be a powerful tool for identifying osteoblast-targeting candidates; however, this approach is generally limited with using only one molecule as a cell-based sensor that does not always reflect the activation of the osteogenic phenotype. In the present study, we used the MC3T3-E1 cell line stably transfected with the green fluorescent protein (GFP) reporter gene driven by a fragment of type I collagen promoter (Col-1a1GFP-MC3T3-E1) to evaluate a double-screening system to identify osteogenic inducible compounds using a combination of a cell-based reporter assay and detection of alkaline phosphatase (ALP) activity. Col-1a1GFP-MC3T3-E1 cells were cultured in an osteogenic induction medium after library screening of 1280 pharmacologically active compounds (Lopack¹²⁸⁰). After 7 days, GFP fluorescence was measured using a microplate reader. After 14 days of osteogenic induction, the cells were stained with ALP. Library screening using the Col-1a1/GFP reporter and ALP staining assay detected three candidates with significant osteogenic induction ability. Furthermore, leflunomide, one of the three detected candidates, significantly promoted new bone formation in vivo. Therefore, this double-screening method could identify candidates for osteogenesis-targeting compounds more reliably than conventional methods.

Nutraceutical Approach to Chronic Osteoarthritis: From Molecular Research to Clinical Evidence

Osteoarthritis (OA) is a degenerative inflammatory condition of the joint cartilage that currently affects approximately 58 million adults in the world. It is characterized by pain, stiffness, and a reduced range of motion with regard to the arthritic joints. These symptoms can cause in the long term a greater risk of overweight/obesity, diabetes mellitus, and falls and fractures. Although the current guidelines for the treatment of OA suggest, as the gold standard for this condition, pharmacological treatment characterized by non-steroidal anti-inflammatory drugs (NSAID), opioids, and cyclooxygenase (COX)-2-specific drugs, a great interest has been applied to nutraceutical supplements, which include a heterogeneous class of molecules with great potential to reduce inflammation, oxidative stress, pain, and joint stiffness and improve cartilage formation. The purpose of this review is to describe the potential application of nutraceuticals in OA, highlighting its molecular mechanisms of actions and data of efficacy and safety (when available).

Methylsulfonylmethane Increases the Alveolar Bone Density of Mandibles in Aging Female Mice

Methylsulfonylmethane (MSM) is a naturally occurring anti-inflammatory compound that effectively treats multiple degenerative diseases such as osteoarthritis and acute pancreatitis. Our previous studies have demonstrated the ability of MSM to differentiate stem cells from human exfoliated deciduous (SHED) teeth into osteoblast-like cells. This study examined the systemic effect of MSM in 36-week-old aging C57BL/6 female mice in vivo by injecting MSM for 13 weeks. Serum analyses showed an increase in expression levels of bone formation markers [osteocalcin (OCN) and procollagen type 1 intact N-terminal propeptide (P1NP)] and a reduction in bone resorption markers [tartrate-resistant acid phosphatase (TRAP) and C-terminal telopeptide of type I collag (CTX-I)] in MSM-injected animals. Micro-computed tomographic images demonstrated an increase in trabecular bone density in mandibles. The trabecular bone density tended to be higher in the femur, although the increase was not significantly different between the MSM- and phosphate-buffered saline (PBS)-injected mice. In mandibles, an increase in bone density with a corresponding decrease in the marrow cavity was observed in the MSM-injected mice. Furthermore, immunohistochemical analyses of the mandibles for the osteoblast-specific marker - OCN, and the mesenchymal stem cell-specific marker - CD105 showed a significant increase and decrease in OCN and CD105 positive cells, respectively. Areas of bone loss were observed in the inter-radicular region of mandibles in control mice. However, this loss was considerably decreased due to stimulation of bone formation in response to MSM injection. In conclusion, our study has demonstrated the ability of MSM to induce osteoblast formation and function in vivo, resulting in increased bone formation in the mandible. Hence, the application of MSM and stem cells of interest may be the right combination in alveolar bone regeneration under periodontal or other related diseases that demonstrate bone loss.

Biological Functions of Let-7e-5p in Promoting the Differentiation of MC3T3-E1 Cells

MicroRNAs let-7c and let-7f, two members of the let-7 family, were involved in regulating osteoblast differentiation and have an important role in bone formation. Let-7e-5p, which also belonged to the let-7 family, presented in the differentiation of adipose-derived stem cells and mouse embryonic stem cells. However, the role of let-7e-5p in osteoblast differentiation was unclear. Thus, this study aimed to elucidate the function of let-7e-5p in osteoblast differentiation and its mechanism. Firstly, we found that the let-7e-5p mimic promoted osteoblast differentiation but not the proliferation of MC3T3-E1 cells by positively regulating the expression levels of osteogenic-associated genes (RUNX2, OCN, OPN, and OSX), the activity of ALP, and formation of mineralized nodules. Moreover, we ascertained that the let-7e-5p mimic downregulated the post-transcriptional expression of SOCS1 by specifically binding to the 3′ untranslated region of SOCS1 mRNA. Also, let-7e-5p-induced SOCS1 downregulation increased the protein levels of p-STAT5 and IGF-1, which were both modulated by SOCS1 molecules. Furthermore, let-7e-5p abrogated the inhibition of osteogenic differentiation mediated by SOCS1 overexpression. Therefore, these results suggested that let-7e-5p regulated the differentiation of MC3T3-E1 cells through the JAK2/STAT5 pathway to upregulate IGF-1 gene expression by inhibiting SOCS1. These findings may provide a new insight into the regulatory role of let-7e-5p in osteogenic differentiation and imply the existence of a novel mechanism underlying let-7e-5p-mediated osteogenic differentiation.

Methylsulfonylmethane enhances MSC chondrogenic commitment and promotes pre-osteoblasts formation

BACKGROUND

Methylsulfonylmethane (MSM) is a nutraceutical compound which has been indicated to counteract osteoarthritis, a cartilage degenerative disorder. In addition, MSM has also been shown to increase osteoblast differentiation. So far, few studies have investigated MSM role in the differentiation of mesenchymal stem cells (MSCs), and no study has been performed to evaluate its overall effects on both osteogenic and chondrogenic differentiation. These two mutually regulated processes share the same progenitor cells.

METHODS

Therefore, with the aim to evaluate the effects of MSM on chondrogenesis and osteogenesis, we analyzed the expression of SOX9, RUNX2, and SP7 transcription factors in vitro (mesenchymal stem cells and chondrocytes cell lines) and in vivo (zebrafish model). Real-time PCR as well Western blotting, immunofluorescence, and specific in vitro and in vivo staining have been performed. Student's paired t test was used to compare the variation between the groups.

RESULTS

Our data demonstrated that MSM modulates the expression of differentiation-related genes both in vitro and in vivo. The increased SOX9 expression suggests that MSM promotes chondrogenesis in treated samples. In addition, RUNX2 expression was not particularly affected by MSM while SP7 expression increased in all MSM samples/model analyzed. As SP7 is required for the final commitment of progenitors to preosteoblasts, our data suggest a role of MSM in promoting preosteoblast formation. In addition, we observed a reduced expression of the osteoclast-surface receptor RANK in larvae and in scales as well as a reduced pERK/ERK ratio in fin and scale of MSM treated zebrafish.

CONCLUSIONS

In conclusion, our study provides new insights into MSM mode of action and suggests that MSM is a useful tool to counteract skeletal degenerative diseases by targeting MSC commitment and differentiation.

Regulation and Role of Transcription Factors in Osteogenesis

Bone is a dynamic tissue constantly responding to environmental changes such as nutritional and mechanical stress. Bone homeostasis in adult life is maintained through bone remodeling, a controlled and balanced process between bone-resorbing osteoclasts and bone-forming osteoblasts. Osteoblasts secrete matrix, with some being buried within the newly formed bone, and differentiate to osteocytes. During embryogenesis, bones are formed through intramembraneous or endochondral ossification. The former involves a direct differentiation of mesenchymal progenitor to osteoblasts, and the latter is through a cartilage template that is subsequently converted to bone. Advances in lineage tracing, cell sorting, and single-cell transcriptome studies have enabled new discoveries of gene regulation, and new populations of skeletal stem cells in multiple niches, including the cartilage growth plate, chondro-osseous junction, bone, and bone marrow, in embryonic development and postnatal life. Osteoblast differentiation is regulated by a master transcription factor RUNX2 and other factors such as OSX/SP7 and ATF4. Developmental and environmental cues affect the transcriptional activities of osteoblasts from lineage commitment to differentiation at multiple levels, fine-tuned with the involvement of co-factors, microRNAs, epigenetics, systemic factors, circadian rhythm, and the microenvironments. In this review, we will discuss these topics in relation to transcriptional controls in osteogenesis.

Osteogenic Properties of Novel Methylsulfonylmethane-Coated Hydroxyapatite Scaffold

Despite numerous advantages of using porous hydroxyapatite (HAp) scaffolds in bone regeneration, the material is limited in terms of osteoinduction. In this study, the porous scaffold made from nanosized HAp was coated with different concentrations of osteoinductive aqueous methylsulfonylmethane (MSM) solution (2.5, 5, 10, and 20%) and the corresponding MH scaffolds were referred to as MH2.5, MH5, MH10, and MH20, respectively. The results showed that all MH scaffolds resulted in burst release of MSM for up to 7 d. Cellular experiments were conducted using MC3T3-E1 preosteoblast cells, which showed no significant difference between the MH2.5 scaffold and the control with respect to the rate of cell proliferation (p > 0.05). There was no significant difference between each group at day 4 for alkaline phosphatase (ALP) activity, though the MH2.5 group showed higher level of activity than other groups at day 10. Calcium deposition, using alizarin red staining, showed that cell mineralization was significantly higher in the MH2.5 scaffold than that in the HAp scaffold (p < 0.0001). This study indicated that the MH2.5 scaffold has potential for both osteoinduction and osteoconduction in bone regeneration.

A novel role of FKN/CX3CR1 in promoting osteogenic transformation of VSMCs and atherosclerotic calcification

Fractalkine (FKN) and its specific receptor CX3CR1 play a critical role in the pathogenesis of atherosclerosis including recruitment of vascular cells and the development of inflammation. However, its contribution to regulating the development of atherosclerotic calcification has not been well documented. Osteogenic transformation of vascular smooth muscle cells (VSMCs) is critical in the development of calcification in atherosclerotic lesions. In this study, for the first time, we evaluated the effect of FKN/CX3CR1 on the progression of VSMCs calcification and defined molecular signaling that is operative in the FKN/CX3CR1-induced osteogenic transformation of VSMCs. We found that high-fat diet induced atherosclerotic calcification in vivo was markedly inhibited in the Apolipoprotein E (ApoE) and CX3CR1 deficient (ApoE^-/-/CX3CR1^-/-) mice compared with their control littermates. FKN and CX3CR1 were both expressed in VSMCs and up-regulated by oxidized low-density lipoprotein (ox-LDL). FKN/CX3CR1 promoted the expression of osteogenic markers, including osteopontin (OPN), bone morphogenetic protein (BMP)-2 and alkaline phosphatase (ALP) and decreased VSMCs markers, including smooth muscle (SM) α-actin and SM22-α in a dose-dependent manner. The essential role of FKN/CX3CR1 in VSMCs calcification was further confirmed by lentivirus-mediated knockdown or overexpression of CX3CR1 blocked or accelerated osteogenic transformation of VSMCs. This response was associated with reciprocal up- and down-regulation of osteogenic factor, runt-related transcription factor 2 (RUNX2), transcription factors in osteoclast differentiation, receptor activator of nuclear factor-κB (RANK), RANK ligand (RNAKL) and osteoprotegerin (OPG), respectively. Inhibition of FKN/CX3CR1-activated Jak2/Stat3 signaling by the Jak/Stat inhibitor AG490 blocked osteogenic transformation of VSMCs and RUNX2 induction concurrently. Taken together, our data uncovered novel roles of FKN/CX3CR1 in promoting VSMC osteogenic transformation and atherosclerotic calcification by activating RUNX2 through Jak2/Stat3 signaling pathway and suppressing OPG. Our findings suggest that targeting FKN/CX3CR1 may provide new strategies for the prevention and treatment of atherosclerotic calcification.

Potential Biomarkers of the Turnover, Mineralization, and Volume Classification: Results Using NMR Metabolomics in Hemodialysis Patients

Bone biopsy is still the gold standard to assess bone turnover (T), mineralization (M), and volume (V) in CKD patients, and serum biomarkers are not able to replace histomorphometry. Recently, metabolomics has emerged as a new technique that could allow for the identification of new biomarkers useful for disease diagnosis or for the understanding of pathophysiologic mechanisms, but it has never been assessed in the chronic kidney disease-mineral and bone disorder (CKD-MBD) scenario. In this study, we investigated the association between serum metabolites and the bone TMV classification in patients with end-stage renal disease by using serum NMR spectroscopy and bone biopsy of 49 hemodialysis patients from a single center in Brazil. High T was identified in 21 patients and was associated with higher levels of dimethylsulfone, glycine, citrate, and N-acetylornithine. The receiver-operating characteristic curve for the combination of PTH and these metabolites provided an area under the receiver-operating characteristic curve (AUC) of 0.86 (0.76 to 0.97). Abnormal M was identified in 30 patients and was associated with lower ethanol. The AUC for age, diabetes mellitus, and ethanol was 0.83 (0.71 to 0.96). Low V was identified in 17 patients and was associated with lower carnitine. The association of age, phosphate, and carnitine provided an AUC of 0.83 (0.70 to 0.96). Although differences among the curves by adding selected metabolites to traditional models were not statistically significant, the accuracy of the diagnosis according to the TMV classification seemed to be improved. This is the first study to evaluate the TMV classification system in relation to the serum metabolome assessed by NMR spectroscopy, showing that selected metabolites may help in the evaluation of bone phenotypes in CKD-MBD. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Methylsulfonylmethane Exhibits Bacteriostatic Inhibition of Vancomycin-Resistant Enterococcus faecium, In Vitro

The aim of this study was to evaluate the antibacterial properties of methylsulfonylmethane (MSM) on vancomycin-resistant Enterococcus faecium (VRE). Bacterial proliferation was measured spectrophotometrically during growth in brain heart infusion broth with 0%, 3%, 5%, 7%, 10%, 12%, and 16% MSM. To assess the mechanism of inhibition, VRE was grown overnight with 0-16% MSM and enumerated on unmedicated and medicated (3-16% MSM) brain heart infusion agar (BHIA). Viability studies were performed to evaluate the impact of 10-16% MSM on VRE over 7 days. Absorbance data indicated a dose-dependent inhibition from 0% to 7% MSM and no increase in optical density in 10-16% MSM. VRE enumerated on unmedicated BHIA from overnight cultures with 10-16% MSM partially recovered. No growth was observed when BHIA contained 10-16% MSM. There was little effect on VRE growth in 10% MSM over 7 days. VRE displayed a population rebound on day 6 when exposed to 12% MSM, and elimination by day 6 in 16% MSM. Regrowth after MSM removal may be indicative of a bacteriostatic mechanism of inhibition. Cell elimination in 16% MSM suggests inhibition of an essential metabolic function from which the bacterium could not recover.

The potential function of miR-135b-mediated JAK2/STAT3 signaling pathway during osteoblast differentiation

MC3T3-E1 cells were divided into Blank, miR-135b mimics, miR-135b inhibitors, AG490, and miR-135b inhibitors + AG490 groups. Cell viability was determined by MTT, alkaline phosphatase (ALP) activity by the corresponding kit, and mineralization by alizarin red staining. Furthermore, miR-135b, osteoblast-specific genes, and JAK2/STAT3 were detected through quantitative real-time polymerase chain reaction and Western blotting. MiR-135b downregulation was identified with increased JAK2 during osteoblast differentiation. JAK2 was confirmed as a target gene of miR-135b by dual-luciferase reporter assay. MC3T3-E1 cells in both miR-135b mimics and AG490 groups manifested decrease in cell viability, ALP activity, and mineralized nodes, as well as reductions in osteoblast-specific genes and proteins of JAK2, p-JAK2, and p-STAT3, but increase in cell apoptosis. However, opposite changes of the above factors were shown in cells from miR-135b inhibitors group. Notably, AG490 could reverse promotion effects of miR-135b inhibitors on osteoblast differentiation. Inhibiting miR-135b could activate the JAK2/STAT3 signaling pathway, thereby improving the cell viability and promoting the osteoblast differentiation.

TGFβ1 induces bone formation from BMP9-activated Bone Mesenchymal Stem Cells, with possible involvement of non-canonical pathways

Reconstruction of bone defects is one of the most substantial and difficult clinical challenges in orthopedics. Transforming growth factor beta 1 (TGFβ1) might play an important role in stimulating osteogenic differentiation of bone morphogenetic protein 9 (BMP9)-induced C3H10T1/2 mesenchymal stem cells. In our current study, we examined the potential synergy between TGFβ1 and BMP9 in promoting the osteogenesis of C3H10T1/2 cells, and whether such effects could contribute to bone formation in vivo. Our experiment data indicated that TGFβ1 could increase the expression of osteogenic markers and the formation of mineralized calcium nodules in, while suppressing the proliferation of, BMP9-induced C3H10T1/2 cells. Furthermore, mice intramuscularly injected with BMP9/TGFβ1-transduced C3H10T1/2 cells into the gastrocnemius muscle on their tibiae developed ectopic bone masses with more mature osteoid structures, compared to those grafted with cells expressing BMP9/RFP. Subsequent mechanistic studies found that TGFβ1-induced enhancement of osteogenesis in BMP9-overexpressing C3H10T1/2 cells was accompanied by augmented expression of heat shock protein 47 (HSP47), a collagen-specific molecular chaperone essential for collagen biosynthesis, and can be attenuated by pirfenidone, a known anti-fibrotic inhibitor. Interestingly, protein microarray analysis suggested that TGFβ1/BMP9-dependent osteogenesis of C3H10T1/2 cells seemed to involve several non-canonical signaling pathways such as Janus kinase-signal transducer and activator of transcription, phosphoinositide-3-kinase-protein kinase B, and mitogen-activated protein kinase. These results provided further evidence that TGFβ1 could promote bone formation from BMP9-induced C3H10T1/2 cells and shed important light on the underlying molecular mechanisms.

Non‑toxic sulfur enhances growth hormone signaling through the JAK2/STAT5b/IGF‑1 pathway in C2C12 cells

Insulin‑like growth factor‑1 (IGF‑1) regulates cell growth, glucose uptake and protein metabolism, and is required for growth hormone (GH) signaling‑mediated insulin production and secretion. IGF1 expression is associated with STAT5, which binds to a region (TTCNNNGAA) of the gene. Although sulfur is used in various fields, the toxicity of this element is a significant disadvantage as it causes indigestion, vomiting, diarrhea, pain and migraine. Therefore, it is difficult to conduct in vitro experiments to directly determine the effects of dietary sulfur. Additionally, it is difficult to dissolve non‑toxic sulfur (NTS). The present study aimed to identify the role of NTS in GH signaling as a Jak2/STAT5b/IGF‑1 pathway regulator. MTT assay was used to identify an optimum NTS concentration for C2C12 mouse muscle cells. Western blotting, RT‑PCR, chromatin immunoprecipitation, overexpression and small interfering RNA analyses were performed. NTS was dissolved in 1 mg/ml DMSO and could be used in vitro. Therefore, the present study determined whether NTS induced mouse muscle cell growth via GH signaling. NTS notably increased STAT5b binding to the Igf1 promoter. NTS also promoted GH signaling by upregulating GH receptor expression, similar to GH treatment. NTS enhanced GH signaling by regulating Jak2/STAT5b/IGF‑1 signaling pathway factor expression in C2C12 mouse muscle cells. Thus, NTS may be used as a GH‑enhancing growth stimulator.

Methylsulfonylmethane increases osteogenesis and regulates the mineralization of the matrix by transglutaminase 2 in SHED cells

Methylsulfonylmethane (MSM) is a naturally occurring, sulfate-containing, organic compound. It has been shown to stimulate the differentiation of mesenchymal stem cells into osteoblast-like cells and bone formation. In this study, we investigated whether MSM influences the differentiation of stem cells from human exfoliated deciduous teeth (SHED) into osteoblast-like cells and their osteogenic potential. Here, we report that MSM induced osteogenic differentiation through the expression of osteogenic markers such as osterix, osteopontin, and RUNX2, at both mRNA and protein levels in SHED cells. An increase in the activity of alkaline phosphatase and mineralization confirmed the osteogenic potential of MSM. These MSM-induced effects were observed in cells grown in basal medium but not osteogenic medium. MSM induced transglutaminase-2 (TG2), which may be responsible for the cross-linking of extracellular matrix proteins (collagen or osteopontin), and the mineralization process. Inhibition of TG2 ensued a significant decrease in the differentiation of SHED cells and cross-linking of matrix proteins. A comparison of mineralization with the use of mineralized and demineralized bone particles in the presence of MSM revealed that mineralization is higher with mineralized bone particles than with demineralized bone particles. In conclusion, these results indicated that MSM could promote differentiation and osteogenic potential of SHED cells. This osteogenic property is more in the presence of mineralized bone particles. TG2 is a likely cue in the regulation of differentiation and mineral deposition of SHED cells in response to MSM.

Methylsulfonylmethane inhibits cortisol-induced stress through p53-mediated SDHA/HPRT1 expression in racehorse skeletal muscle cells: A primary step against exercise stress

Cortisol is a hormone involved in stress during exercise. The application of natural compounds is a new potential approach for controlling cortisol-induced stress. Tumour suppressor protein p53 is activated during cellular stress. Succinate dehydrogenase complex subunit A (SDHA) and hypoxanthine phosphoribosyl transferase 1 (HPRT1) are considered to be two of the most stable reference genes when measuring stress during exercise in horses. In the present study cells were considered to be in a 'stressed state' if the levels of these stable genes and the highly stress responsive gene p53 were altered. It was hypothesized that a natural organic sulphur-containing compound, methylsulfonylmethane (MSM), could inhibit cortisol-induced stress in racing horse skeletal muscle cells by regulating SDHA, HPRT1 and p53 expression. After assessing cell viability using MTT assays, 20 µg/ml cortisol and 50 mM MSM were applied to horse skeletal muscle cell cultures. Reverse transcription-quantitative PCR and western blot analysis demonstrated increases in SDHA, HPRT1 and p53 expression in cells in response to cortisol treatment, which was inhibited or normalized by MSM treatment. To determine the relationship between p53 and SDHA/HPRT1 expression at a transcriptional level, horse gene sequences of SDHA and HPRT1 were probed to identify novel binding sites for p53 in the gene promoters, which were confirmed using a chromatin immunoprecipitation assay. The relationship between p53 and SDHA/HPRT1 expression was confirmed using western blot analysis following the application of pifithrin-α, a p53 inhibitor. These results suggested that MSM is a potential candidate drug for the inhibition of cortisol-induced stress in racehorse skeletal muscle cells.

RNA-binding protein PUM2 regulates mesenchymal stem cell fate via repression of JAK2 and RUNX2 mRNAs

The differentiation of mesenchymal stem cells (MSCs) into unwanted lineages can generate potential problems in clinical trials. Thus, understanding the molecular mechanisms, involved in this process, would help prevent unexpected complications. Regulation of gene expression, at the posttranscriptional level, is a new approach in cell therapies. PUMILIO is a conserved posttranscriptional regulator. However, the underlying mechanisms of PUMILIO, in vertebrate stem cells, remain elusive. Here, we show that depletion of PUMILIO2 (PUM2) blocks MSC adipogenesis and enhances osteogenesis. We also demonstrate that PUM2 works as a negative regulator on the 3'-untranslated regions of JAK2 and RUNX2 via direct binding. CRISPR/Cas9-mediated gene silencing of Pum2 inhibited lipid accumulation and induced excessive bone formation in zebrafish larvae. Our findings reveal novel roles of PUM2 in MSCs and provide potential therapeutic targets for related diseases.

Methylsulfonylmethane exhibits bacteriostatic inhibition of Escherichia coli, and Salmonella enterica Kinshasa, in vitro

AIMS

To evaluate antibacterial properties of methylsulfonylmethane (MSM) on Escherichia coli (MDRE21) and Salmonella enterica serovar Kinshasa (SK132).

METHODS AND RESULTS

Bacterial proliferation analysis was measured spectrophotometrically during log phase growth with 0, 3, 5, 7, 10, 12 and 16% MSM. To assess the mechanism of inhibition, cultures were grown overnight with 0-16% MSM and enumerated on unmedicated brain-heart infusion agar (BHIA) or BHIA with 0-16% MSM. The long-term viability studies were done to evaluate the impact of 10% MSM. Absorbance data indicated a dose-dependent inhibition from 0 to 16% MSM. There was no growth of MDRE21 or SK132 on BHIA in 10-16% MSM. Both strains enumerated on unmedicated BHIA from overnight cultures with 10-16% MSM were able to partially recover.

CONCLUSIONS

Recovery after MSM removal may be indicative of a bacteriostatic mechanism of inhibition. The long-term viability studies illustrated that neither MDRE21 nor SK132 could be rescued from 10% MSM after 5 or 6 days respectively.

SIGNIFICANCE AND IMPACT OF THE STUDY

Methylsulfonylmethane antibacterial activity may prove useful during pre or postharvest food safety as a disinfectant. The primary benefit being, its clinical safety to humans. Comparisons to other disinfectants would also need to be done to determine if MSM was superior to those already on the market and would be cost effective.

Immunoregulatory role of exosomes derived from differentiating mesenchymal stromal cells on inflammation and osteogenesis

Bone marrow-derived mesenchymal stem/stromal cells (BMSCs) can differentiate into bone-forming osteoblasts, playing a crucial role in bone regeneration. Exosomes are naturally cell-secreted nanovesicles and are lately regraded as an emerging mediator of cellular communication in physiological and pathological conditions. The present study aimed at investigating the complex cellular communications, especially those among the differentiating BMSCs, immune cells (e.g., macrophages), and newly recruited BMSCs via exosome-mediated pathways. Exosomes were first isolated from osteogenically differentiating BMSCs at various stages (Day 0, Day 3, Day 7, and Day 14, respectively). The cellular uptake of isolated exosomes was examined in macrophages and human BMSCs (hBMSCs). The exosomes collected at various osteogenic differentiation stages (0d-exo, 3d-exo, 7d-exo, and 14d-exo) had no effect on the viability of hBMSCs. The uptake of exosomes (0d-exo, 3d-exo, and 7d-exo) significantly decreased proinflammatory-gene expression and the level of an M1 phenotypic marker. Our results then revealed that 3d-exo, 7d-exo, and 14d-exo led to a remarkable increase in mesenchymal stem/stromal cell migration. In addition, 0d-exo significantly promoted the expression of early osteogenic markers, such as alkaline phosphatase and bone morphogenetic protein 2, indicating a pro-osteogenic role of hBMSC-derived exosomes. Collectively, these results suggest that exosomes derived from differentiating mesenchymal stem/stromal cells play a unique osteoimmunomodulatory role in the regulation of bone dynamics.

Hypoxia-responsive miRNA-21-5p inhibits Runx2 suppression by targeting SMAD7 in MC3T3-E1 cells

Sustained hypoxia inhibits osteogenesis and osteoblast differentiation by downregulating the expression of runt‐related transcription factor 2 (Runx2). MicroRNAs (miRNAs) have been shown to regulate osteogenesis and osteoblast differentiation. In the present study, we profiled miRNAs, with microRNA array and quantitative real‐time polymerase chain reaction (RT‐PCR) methods, in mouse osteoblast (MC3T3‐E1) cells under hypoxia. Then, we investigated regulation by miRNA‐21‐5p on the expression of Runx2 and other osteoblast differentiation‐associated markers via gain‐of‐function and loss‐of‐function strategies. We found that expression of miRNA‐21‐5p, miRNA‐210‐5p, and other eight miRNAs was upregulated significantly in hypoxia‐treated MC3T3‐E1 cells. miRNA‐21‐5p overexpression downregulated the expression of the mRNA and protein of suppressor of mothers against decapentaplegic (SMAD7) markedly, the 3′‐untranslated region (3′‐UTR) of which was highly homologous with the miRNA‐21‐5p sequence. miRNA‐21‐5p overexpression upregulated the protein expression of Runx2 in hypoxia‐treated MC3T3‐E1 cells, although mRNA expression of Runx2 and other osteoblast differentiation‐associated molecules (eg, osteocalcin, procollagen type 1 amino‐terminal propeptide, P1NP) were not regulated by it; such upregulation was SMAD7‐dependent. In conclusion, hypoxia‐responsive miRNA‐21‐5p promoted Runx2 expression (at least in part) by targeting the 3′‐UTR and downregulating SMAD7 expression. Our study suggests a protective role of miRNA‐21‐5p in promoting osteoblast differentiation under hypoxia.

A non-canonical JAGGED1 signal to JAK2 mediates osteoblast commitment in cranial neural crest cells

During craniofacial development, cranial neural crest (CNC) cells migrate into the developing face and form bone through intramembranous ossification. Loss of JAGGED1 (JAG1) signaling in the CNC cells is associated with maxillary hypoplasia or maxillary bone deficiency (MBD) in mice and recapitulates the MBD seen in humans with Alagille syndrome. JAGGED1, a membrane-bound NOTCH ligand, is required for normal craniofacial development, and Jagged1 mutations in humans are known to cause Alagille Syndrome, which is associated with cardiac, biliary, and bone phenotypes and these children experience increased bony fractures. Previously, we demonstrated deficient maxillary osteogenesis in Wnt1-cre;Jagged1^f/f (Jag1CKO) mice by conditional deletion of Jagged1 in maxillary CNC cells. In this study, we investigated the JAG1 signaling pathways in a CNC cell line. Treatment with JAG1 induced osteoblast differentiation and maturation markers, Runx2 and Ocn, respectively, Alkaline Phosphatase (ALP) production, as well as classic NOTCH1 targets, Hes1 and Hey1. While JAG1-induced Hes1 and Hey1 expression levels were predictably decreased after DAPT (NOTCH inhibitor) treatment, JAG1-induced Runx2 and Ocn levels were surprisingly constant in the presence of DAPT, indicating that JAG1 effects in the CNC cells are independent of the canonical NOTCH pathway. JAG1 treatment of CNC cells increased Janus Kinase 2 (JAK2) phosphorylation, which was refractory to DAPT treatment, highlighting the importance of the non-canonical NOTCH pathway during CNC cells osteoblast commitment. Pharmacologic inhibition of JAK2 phosphorylation, with and without DAPT treatment, upon JAG1 induction reduced ALP production and, Runx2 and Ocn gene expression. Collectively, these data suggest that JAK2 is an essential component downstream of a non-canonical JAG1-NOTCH1 pathway through which JAG1 stimulates expression of osteoblast-specific gene targets in CNC cells that contribute to osteoblast differentiation and bone mineralization.

Growth hormone facilitates 5'-azacytidine-induced myogenic but inhibits 5'-azacytidine-induced adipogenic commitment in C3H10T1/2 mesenchymal stem cells

The C3H10T1/2 cells are considered mesenchymal stem cells (MSCs) because they can be induced to become the progenitor cells for myocytes, adipocytes, osteoblasts, and chondrocytes by the DNA methyltransferase inhibitor 5'-azacytidine. In this study, we determined the effect of growth hormone (GH) on the myogenic and adipogenic lineage commitment in C3H10T1/2 cells. The C3H10T1/2 cells were treated with recombinant bovine GH in the presence or absence of 5'-azacytidine for 4 days. The myogenic commitment in C3H10T1/2 cells was assessed by immunostaining them for MyoD, the marker for myoblasts, and by determining their capacity to differentiate into the multinucleated myotubes. The adipogenic commitment in C3H10T1/2 cells was assessed by determining their ability to differentiate into adipocytes. Myotubes and adipocyteswere identified by immunocytochemistry and Oil Red O staining, respectively. C3H10T1/2 cells treated with 5'-azacytidine and GH for 4 days contained a greater percentage of MyoD-positive cells than those treated with 5'-axacytidine alone (P < 0.05). The former generated more myotubes than the latter upon induced myoblast differentiation (P < 0.05). However, C3H10T1/2 cells treated with GH alone did not form any myotubes. C3H10T1/2 cells treated with 5'-azacytidine formed adipocytes upon adipocyte differentiation induction, whereas C3H10T1/2 cells treated with GH alone did not form any adipocytes. C3H10T1/2 cells treated with both 5'-azacytidine and GH formed fewer adipocytes than those treated with 5'-azacytidine alone (P < 0.05). Both GHR and IGF-I mRNA expression in C3H10T1/2 cells were increased by 5'-azacytidine (P < 0.05), but neither was affected by GH. Overall, this study showed that GH enhanced 5'-azacytidine-induced commitment in C3H10T1/2 cells to myoblasts but inhibited 5'-azacytidine-induced commitment to preadipocytes. These results support the possibility that GH stimulates skeletal muscle growth and inhibits adipose tissue growth in part by stimulating the myogenic commitment and inhibiting the adipogenic commitment, respectively, in mesenchymal stem cells.

Hsa-let-7c controls the committed differentiation of IGF-1-treated mesenchymal stem cells derived from dental pulps by targeting IGF-1R via the MAPK pathways

The putative tumor suppressor microRNA let-7c is extensively associated with the biological properties of cancer cells. However, the potential involvement of let-7c in the differentiation of mesenchymal stem cells has not been fully explored. In this study, we investigated the influence of hsa-let-7c (let-7c) on the proliferation and differentiation of human dental pulp-derived mesenchymal stem cells (DPMSCs) treated with insulin-like growth factor 1 (IGF-1) via flow cytometry, CCK-8 assays, alizarin red staining, real-time RT-PCR, and western blotting. In general, the proliferative capabilities and cell viability of DPMSCs were not significantly affected by the overexpression or deletion of let-7c. However, overexpression of let-7c significantly inhibited the expression of IGF-1 receptor (IGF-1R) and downregulated the osteo/odontogenic differentiation of DPMSCs, as indicated by decreased levels of several osteo/odontogenic markers (osteocalcin, osterix, runt-related transcription factor 2, dentin sialophosphoprotein, dentin sialoprotein, alkaline phosphatase, type 1 collagen, and dentin matrix protein 1) in IGF-1-treated DPMSCs. Inversely, deletion of let-7c resulted in increased IGF-1R levels and enhanced osteo/odontogenic differentiation. Furthermore, the ERK, JNK, and P38 MAPK pathways were significantly inhibited following the overexpression of let-7c in DPMSCs. Deletion of let-7c promoted the activation of the JNK and P38 MAPK pathways. Our cumulative findings indicate that Let-7c can inhibit the osteo/odontogenic differentiation of IGF-1-treated DPMSCs by targeting IGF-1R via the JNK/P38 MAPK signaling pathways.

Sexual Dimorphism and the Origins of Human Spinal Health

Recent observations indicate that the cross-sectional area (CSA) of vertebral bodies is on average 10% smaller in healthy newborn girls than in newborn boys, a striking difference that increases during infancy and puberty and is greatest by the time of sexual and skeletal maturity. The smaller CSA of female vertebrae is associated with greater spinal flexibility and could represent the human adaptation to fetal load in bipedal posture. Unfortunately, it also imparts a mechanical disadvantage that increases stress within the vertebrae for all physical activities. This review summarizes the potential endocrine, genetic, and environmental determinants of vertebral cross-sectional growth and current knowledge of the association between the small female vertebrae and greater risk for a broad array of spinal conditions across the lifespan.

Astragalus Extract Mixture HT042 Increases Longitudinal Bone Growth Rate by Upregulating Circulatory IGF-1 in Rats

Astragalus extract mixture HT042 is a standardized ingredient of health functional food approved by Korean FDA with a claim of “height growth of children.” HT042 stimulates bone growth rate and increases local IGF-1 expression in growth plate of rats which can be considered as direct stimulation of GH and its paracrine/autocrine actions. However, it remains unclear whether HT042 stimulates circulatory IGF-1 which also plays a major role to stimulate bone growth. To determine the effects on circulatory IGF-1, IGF-1 and IGFBP-3 expressions and phosphorylation of JAK2/STAT5 were evaluated in the liver after 10 days of HT042 administration. HT042 upregulated liver IGF-1 and IGFBP-3 mRNA expression, IGF-1 protein expression, and phosphorylation of JAK2/STAT5. HT042 also increased bone growth rate and proliferative zonal height in growth plate. In conclusion, HT042 stimulates bone growth rate via increment of proliferative rate by upregulation of liver IGF-1 and IGFBP-3 mRNA followed by IGF-1 protein expression through phosphorylation of JAK2/STAT5, which can be regarded as normal functioning of GH-dependent endocrine pathway.

Liuwei Dihuang Pill () Treats Postmenopausal Osteoporosis with Shen (Kidney) Yin Deficiency via Janus Kinase/Signal Transducer and Activator of Transcription Signal Pathway by Up-regulating Cardiotrophin-Like Cytokine Factor 1 Expression

OBJECTIVES

To investigate the mechanism of Liuwei Dihuang Pill (, LDP) in treating postmenopausal osteoporosis (PMOP) with Shen (Kidney) yin deficiency.

METHODS

In this study, 205 cases of PMOP were divided into the PMOP Shen-yin deficiency group (Group A), PMOP Shen-yang deficiency group (Group B), PMOP without Shen deficiency group (Group C), and control group (Group N). Real-time polymerase chain reaction (RT-PCR) and Western blot techniques were used to observe the effects of LDP treatment on the cardiotrophin-like cytokine factor 1 (CLCF1), ankyrin repeat and SOCS box containing 1 (ASB1), and prokineticin 2 (PROK2) genes and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway.

RESULTS

The mRNA (P<0.05) and protein (P<0.01) expression levels of the CLCF1 gene in Group A were significantly lower than the corresponding levels in Group N. After LDP treatment for 3 months, the mRNA expression levels of the CLCF1 gene were obviously up-regulated (P<0.01). After 6-month treatment, the expression levels of CLCF1 mRNA and protein were significantly up-regulated (both P<0.01), and the average bone density of the top femur had significantly increased (P<0.05). In vitro, CLCF1 overexpression resulted in a significant increase in the total protein and phosphorylated protein levels of JAK2 and STAT3.

CONCLUSIONS

The CLCF1 gene is an important gene associated with PMOP Shen-yin deficiency and the therapeutic effects of LDP may be mediated by up-regulation of CLCF1 gene expression and activation of the JAK/STAT signaling pathway.

Methylsulfonylmethane Inhibits RANKL-Induced Osteoclastogenesis in BMMs by Suppressing NF-κB and STAT3 Activities

Osteoclast differentiation is dependent on the activities of receptor activator NF-kB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). Given that RANKL plays a critical role in osteoclast formation and bone resorption, any new compounds found to alter its activity would be predicted to have therapeutic potential for disorders associated with bone loss. Methylsulfonylmethane (MSM) is a naturally occurring sulfur compound with well-documented anti-oxidant and anti-inflammatory properties; currently its effects on osteoclast differentiation are unknown. We sought to investigate whether MSM could regulate osteoclastogenesis, and if so, its mechanism of action. In this study, we investigated the effects of MSM on RANKL-induced osteoclast differentiation, together with STAT3’s involvement in the expression of osteoclastic gene markers. These experiments were conducted using bone marrow derived macrophages (BMMs) and cell line material, together with analyses that interrogated both protein and mRNA levels, as well as signaling pathway activity. Although MSM was not toxic to osteoclast precursors, MSM markedly inhibited RANKL-induced TRAP activity, multinucleated osteoclast formation, and bone resorptive activity. Additionally, the expression of several osteoclastogenesis-related marker genes, including TRAF6, c-Fos, NFATc1, cathepsin K, and OSCAR were suppressed by MSM. MSM mediated suppression of RANKL-induced osteoclastogenesis involved inhibition of ITAM signaling effectors such as PLCγ and Syk, with a blockade of NF-kB rather than MAPK activity. Furthermore, MSM inhibited RANKL-induced phosphorylation of STAT3 Ser⁷²⁷. Knockdown of STAT3 using shRNAs resulted in reduced RANKL-mediated phosphorylation of Ser⁷²⁷ STAT3, and TRAF6 in cells for which depletion of STAT3 was confirmed. Additionally, the expression of RANKL-induced osteoclastogenic marker genes were significantly decreased by MSM and STAT3 knockdown. Taken together, these results indicate that STAT3 plays a pivotal role in RANKL-induced osteoclast formation, and that MSM can attenuate RANKL-induced osteoclastogenesis by blocking both NF-kB and STAT3 activity.

Methylsulfonylmethane enhances BMP‑2‑induced osteoblast differentiation in mesenchymal stem cells

As human lifespans have increased, the incidence of osteoporosis has also increased. Methylsulfonylmethane (MSM) affects the process of mesenchymal stem cell (MSC) differentiation into osteoblasts via the Janus kinase 2 (Jak2)/signal transducer and activator of transcription (STAT)5b signaling pathway, and bone morphogenetic protein 2 (BMP‑2) is also known to significantly affect bone health. In addition, the phosphorylation of small mothers against decapentaplegic (Smad)1/5/8 regulates the Runt‑related transcription factor 2 (Runx2) gene, which encodes a transcription factor for osteoblast differentiation markers. In the present study, the differentiation of MSCs treated with MSM, BMP‑2, and their combination were examined. The differentiation of osteoblasts was demonstrated through observation of morphological changes and mineralization, using alizarin red and Von Kossa staining. Western blotting analysis demonstrated that the combination of MSM and BMP-2 increased the phosphorylation of the BMP signaling-associated protein, Smad1/5/8. Combination of MSM and BMP-2 significantly increased osteogenic differentiation and mineralization of the MSCs compared with either MSM or BMP-2 alone. Additionally, reverse transcription-polymerase chain reaction analysis demonstrated that combination of MSM and BMP-2 increased the expression level of the Runx2 gene and the osteoblast differentiation marker genes, alkaline phosphatase, bone sialoprotein and osteocalcin, in MSCs compared with controls. Thus, the combination of MSM and BMP-2 may promote the differentiation of MSCs into osteoblasts.

miR-223 contributes to the AGE-promoted apoptosis via down-regulating insulin-like growth factor 1 receptor in osteoblasts

miR-223 inhibits the advanced glycation end product (AGE)-promoted apoptosis in osteoblasts.

Advanced glycation end products (AGEs) have been confirmed to induce bone quality deterioration in diabetes mellitus (DM), and to associate with abnormal expression of miRNAs in DM patients or in vitro. Recently, miRNAs have been recognized to mediate the onset or progression of DM. In the present study, we investigated the regulation on miR-223 level by AGE-BSA treatment in osteoblast-like MC3T3-E1 cells, with real-time quantitative PCR assay. And then we examined the inhibition of insulin-like growth factor 1 receptor (IGF-1R) expression by miR-223, via targeting of the 3′ UTR of IGF-1R with real-time quantitative PCR, western blotting and luciferase reporter assay. Then we explored the regulation of miR-223 and IGF-1R levels, via the lentivirus-mediated miR-223 inhibition and IGF-1R overexpression in the AGE-BSA-induced apoptosis in MC3T3-E1 cells. It was demonstrated that AGE-BSA treatment with more than 100 μg/ml significantly up-regulated miR-223 level, whereas down-regulated IGF-1R level in MC3T3-E1 cells. And the up-regulated miR-223 down-regulated IGF-1R expression in both mRNA and protein levels, via targeting the 3′ UTR of IGF-1R. Moreover, though the AGE-BSA treatment promoted apoptosis in MC3T3-E1 cells, the IGF-1R overexpression or the miR-223 inhibition significantly attenuated the AGE-BSA-promoted apoptosis in MC3T3-E1 cells. In summary, our study recognized the promotion of miR-223 level by AGE-BSA treatment in osteoblast-like MC3T3-E1 cells. The promoted miR-223 targeted IGF-1R and mediated the AGE-BSA-induced apoptosis in MC3T3-E1 cells. It implies that miR-223 might be an effective therapeutic target to antagonize the AGE-induced damage to osteoblasts in DM.

Methylsulfonylmethane inhibits HER2 expression through STAT5b in breast cancer cells

Breast cancer is the most common cancer in women globally. The factors that increase risk include: late age at first birth, alcohol, radiation exposure, family history of breast cancer, and postmenopausal hormone therapy. Numerous drugs are being developed to treat breast cancer. Among them, Herceptin is used for the treatment of human epidermal growth factor receptor 2 (HER2)-positive cases and targets HER2 effectively and efficiently, but it is very expensive. Methylsulfonylmethane (MSM) is an organic sulfur-containing natural compound having no reported toxicity. We examined MSM in breast cancer cell lines and found it inhibited the proliferation of estrogen receptor-positive and HER2-positive breast cancer cells in a dose-dependent manner. It also suppressed the activation of STAT5b and expression of HER2 in breast cancer cells. We determined the STAT5b binding site (GAS element) in the HER2 gene. Detailed analysis showed that MSM decreased the ability of STAT5b to bind the promoter of the HER2 gene and a luciferase assay demonstrated reduced activity. We confirmed that MSM can effectively regulate STAT5b, and thereby decrease HER2 expression. Therefore, we recommend the use of MSM as an inhibitor for the management of HER2-positive breast cancers.

Protective effects of Tougu Xiaotong capsule on tumor necrosis factor-α-injured UMR-106 cells

Tumor necrosis factor-α (TNF-α) plays an important role in the abnormal metabolism of osteoblasts (OBs), which leads to subchondral bone (SB) alterations in osteoarthritis. In the present study, Tougu Xiaotong capsule (TXC), a traditional Chinese medicine, was used to treat TNF-α-injured OB-like cells. The cellular viability, mortality and ultramicroscopic morphology were evaluated. Thereafter, the activity of alkaline phosphatase (ALP), secretion of osteocalcin (OCN) and mineralization of nodules were analyzed. The results showed that TXC treatment significantly promoted cell proliferation, reduced cellular mortality and improved cellular ultrastructure, particularly that of the endoplasmic reticulum and nucleus. These data indicate that TXC is able to promote cell growth, as well as prevent inflammation in OB-like cells. Furthermore, the activity of ALP, secretion of OCN and mineralization of nodules were accelerated, and the calcium content of the TNF-α-injured OB-like cells was promoted by TXC treatment. These results indicate that TXC protected the OB-like cells from TNF-α-induced injuries. This may be a potential mechanism through which TXC regulates SB remodeling in the clinical treatment of osteoarthritis.

MicroRNAs in Bone Balance and Osteoporosis

Preclinical Research Bone is a rigid and dynamic organ that undergoes continuous turnover. Bone homeostasis is maintained by osteoclast-mediated bone resorption and osteoblast-mediated bone formation. The interruption of this balance can cause various diseases, including osteoporosis a public health issue due to the rate of hip fracture, the most serious outcome of osteoporosis. The bone loss in osteoporosis results from an increase in bone resorption versus bone formation. Thus, regulation of osteoblast and osteoclast activity is a main focus in the treatment of osteoporosis. MicroRNAs (miRNAs) are a class of single stranded noncoding RNAs consisting of 18-22 nucleotides that have an important role in cell differentiation, cell fate, apoptosis, and pathogenesis in various disease states. The potential therapeutic and biomarker function of miRNAs in treating bone disorders is receiving more attention. The current review summarizes the role of miRNAs in bone function at a cellular level in the context of their therapeutic potential.

MicroRNA expression profile of dexamethasone-induced human bone marrow-derived mesenchymal stem cells during osteogenic differentiation

MiRNAs have been identified in various plants and animals where they function in post-transcriptional regulation. Although studies revealed that dexamethasone play a pivotal role in the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs), the identification of specific miRNAs and their regulatory roles in this process remain poorly defined. In this study, microarrays were used to analyze the miRNA expression profile of dexamethasone-induced hBMSCs derived from three donors, and RT-PCRs were used to confirm the microarray results. Nine upregulated miRNAs and seven downregulated miRNAs were identified. The putative target genes of these miRNAs were predicted using bioinformatics analysis. Subsequently, we focused our attention on the functional analysis of an upregulated miRNA, miR-23a. Overexpression of miR-23a inhibited osteogenic differentiation of hBMSCs at the cellular, mRNA, and protein levels. The results of our study provide an experimental basis for further research on miRNAs functions during osteogenic differentiation of dexamethasone-induced hBMSCs.

Taurine, a major amino acid of oyster, enhances linear bone growth in a mouse model of protein malnutrition

Oysters (Oys) contain various beneficial components, such as, antioxidants and amino acids. However, the effects of Oys or taurine (Tau), a major amino acid in Oys on bone growth have not been determined. In the present study, we evaluated the effects of Oys or Tau on linear bone growth in a mouse model of protein malnutrition. To make the protein malnutrition in a mouse, we used a low protein diet. Growth plate thickness was increased by Oys or Tau. Bone volume/tissue volume, trabecular thickness, trabecular number, connection density, and total porosity were also improved by Oys or Tau. Oys or Tau increased insulin-like growth factor-1 (IGF-1) levels in serum, liver, and tibia-growth plate. Phosphorylations of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 5 (STAT5) were increased by Oys and by Tau. These findings show that Oys or Tau may increase growth plate thickness by elevating IGF-1 levels and by promoting the phosphorylations of JAK2-STAT5, and suggest that Oys or Tau are growth-promoting substances of potential use in the food and pharmaceutical industries.

Methylsulfonylmethane-loaded electrospun poly(lactide-co-glycolide) mats for cartilage tissue engineering

The electrospun MSM-loaded PLGA mat is a promising candidate for cartilage regeneration.

Promotion of osteoblast differentiation in mesenchymal cells through Cbl-mediated control of STAT5 activity

The identification of the molecular mechanisms controlling the degradation of regulatory proteins in mesenchymal stromal cells (MSC) may provide clues to promote MSC osteogenic differentiation and bone regeneration. Ubiquitin ligase-dependent degradation of proteins is an important process governing cell fate. In this study, we investigated the role of the E3 ubiquitin ligase c-Cbl in MSC osteoblast differentiation and identified the mechanisms involved in this effect. Using distinct shRNA targeting c-Cbl, we showed that c-Cbl silencing promotes osteoblast differentiation in murine and human MSC, as demonstrated by increased alkaline phosphatase activity, expression of phenotypic osteoblast marker genes (RUNX2, ALP, type 1 collagen), and matrix mineralization in vitro. Coimmunoprecipitation analyses showed that c-Cbl interacts with the transcription factor STAT5, and that STAT5 forms a complex with RUNX2, a master transcription factor controlling osteoblastogenesis. Silencing c-Cbl decreased c-Cbl-mediated STAT5 ubiquitination, increased STAT5 protein level and phosphorylation, and enhanced STAT5 and RUNX2 transcriptional activity. The expression of insulin like growth factor-1 (IGF-1), a target gene of STAT5, was increased by c-Cbl silencing in MSC and in bone marrow stromal cells isolated from c-Cbl deficient mice, suggesting that IGF-1 contributes to osteoblast differentiation induced by c-Cbl silencing in MSC. Consistent with these findings, pharmacological inhibition of STAT5 activity, or neutralization of IGF-1 activity, abrogated the positive effect of c-Cbl knockdown on MSC osteogenic differentiation. Taken together, the data provide a novel functional mechanism by which the ubiquitin ligase c-Cbl regulates the osteoblastic differentiation program in mesenchymal cells by controlling Cbl-mediated STAT5 degradation and activity.

Skeletal response of male mice to anabolic hormone therapy in the absence of the Igfals gene

IGF-I is a critical regulator of skeletal acquisition, which acts in endocrine and autocrine/paracrine modes. In serum, IGF-I is carried by the IGF-binding proteins in binary complexes. Further stabilization of these complexes is achieved by binding to the acid labile subunit (ALS) in a ternary complex (of IGF-I-IGF-binding protein 3/5-ALS). Ablation of the Igfals gene in humans (ALS deficiency) and mice (ALS knockout [ALSKO]) leads to markedly decreased serum IGF-I levels, growth retardation, and impaired skeletal acquisition. To investigate whether hormonal replacement therapy would improve the skeletal phenotype in cases of Igfals gene ablation, we treated male ALSKO mice with GH, IGF-I, or a combination of both. Treatments were administered to animals between 4 and 16 weeks of age or from 8 to 16 weeks of age. Although all treatment groups showed an increase (20%) in serum IGF-I levels, there was no increase in body weight, weight gain, or bone length in either age group. Despite the blunted linear growth in response to hormone therapy, ALSKO mice treated with GH showed radial bone growth, which contributed to bone strength tested by 4-point bending. We found that ALSKO mice treated with GH showed increased total cross-sectional area, cortical bone area, and cortical thickness by microtomography. Dynamic histomorphometry showed that although GH and double treatment groups resulted in trends towards increased bone formation parameters, these did not reach significance. However, bone resorption parameters were significantly increased in all treatment groups. ALSKO mice treated between 4 and 16 weeks of age showed minor differences in bone traits compared with vehicle-treated mice. In conclusion, treatment with GH and IGF-I do not work synergistically to rescue the stunted growth found in mice lacking the Igfals gene. Although GH alone appears to increase bone parameters slightly, it does not affect body weight or linear growth.

JAK2-STAT5B pathway and osteoblast differentiation

Osteoblast differentiation is a critical step in the maintenance of bone homeostasis. Osteoblast differentiation is generally maintained by growth hormone (GH) and various other endocrine and autocrine/paracrine factors. JAK2-STAT5B pathway is a central axis in the mechanism of GH signaling. Similarly, the autocrine/paracrine signaling factor IGF-1 also mediates its effects through this pathway. Analysis on JAK2-STAT5B pathway showed its importance in the IGF-1/IGF-1R mediated regulation of gene expression and osteoblast differentiation. Persistent activation of STAT5B and inhibition of STAT5B degradation showed increased osteoblastic differentiation and STAT5B/Runx-2 activities. Conditional gene silencing studies showed the importance of the JAK2-STAT5B pathway in stimulation of other transcription factors and expression of various differentiation markers.

Effects of growth hormone replacement therapy on bone mineral density in growth hormone deficient adults: a meta-analysis

Objectives. Growth hormone deficiency patients exhibited reduced bone mineral density compared with healthy controls, but previous researches demonstrated uncertainty about the effect of growth hormone replacement therapy on bone in growth hormone deficient adults. The aim of this study was to determine whether the growth hormone replacement therapy could elevate bone mineral density in growth hormone deficient adults. Methods. In this meta-analysis, searches of Medline, Embase, and The Cochrane Library were undertaken to identify studies in humans of the association between growth hormone treatment and bone mineral density in growth hormone deficient adults. Random effects model was used for this meta-analysis. Results. A total of 20 studies (including one outlier study) with 936 subjects were included in our research. We detected significant overall association of growth hormone treatment with increased bone mineral density of spine, femoral neck, and total body, but some results of subgroup analyses were not consistent with the overall analyses. Conclusions. Our meta-analysis suggested that growth hormone replacement therapy could have beneficial influence on bone mineral density in growth hormone deficient adults, but, in some subject populations, the influence was not evident.