Hyperglycemia inhibits osteoblastogenesis of rat bone marrow stromal cells via activation of the Notch2 signaling pathway

Skeletal stem and progenitor cells in bone physiology, ageing and disease

Skeletal stem cells (SSCs) and related progenitors with osteogenic potential, collectively termed skeletal stem and/or progenitor cells (SSPCs), are crucial for providing osteoblasts for bone formation during homeostatic tissue turnover and fracture repair. Besides mediating normal bone physiology, they also have important roles in various metabolic bone diseases, including osteoporosis. SSPCs are of tremendous interest because they represent prime future targets for osteoanabolic therapies and bone regenerative medicine. Remarkable progress has been made in characterizing various SSC and SSPC populations in postnatal bone. SSPCs exist in the periosteum and within the bone marrow stroma, including subsets localizing around arteriolar and sinusoidal blood vessels; they can display osteogenic, chondrogenic, adipogenic and/or fibroblastic potential, and exert critical haematopoiesis-supportive functions. However, much remains to be clarified. By the current markers, bona fide SSCs are commonly contained within broader SSPC populations characterized by considerable heterogeneity and overlap, whose common versus specific functions in health and disease have not been fully unravelled. Here, we review the present knowledge of the identity, fates and relationships of SSPC populations in the postnatal bone environment, their contributions to bone maintenance, the changes observed upon ageing, and the effect of metabolic diseases such as osteoporosis and diabetes mellitus.

Hydrogel Microsphere-Encapsulated Bimetallic Nanozyme for Promoting Diabetic Bone Regeneration via Glucose Consumption and ROS Scavenging

The healing of bone defects among diabetic patients presents a critical challenge due to the pathological microenvironment, characterized by hyperglycemia, excessive reactive oxygen species (ROS) production, and inflammation. Herein, multifunctional composite microspheres, termed GMAP are developed, using a microfluidic technique by incorporating Au@Pt nanoparticles (NPs) and GelMA hydrogel to modulate the diabetic microenvironment for promoting bone regeneration. The GMAP enables the sustained release of Au@Pt NPs, which function as bimetallic nanozymes with dual enzyme-like activities involving glucose oxidase and catalase. The synergistic effect allows for efficient glucose consumption and ROS elimination concurrently. Thus, the GMAP effectively protects the proliferation of bone marrow mesenchymal stem cells (BMSCs) under adverse high-glucose conditions. Furthermore, it also promotes the osteogenic differentiation and paracrine capabilities of BMSCs, and subsequently inhibits inflammation and enhances angiogenesis. In vivo diabetic rats bone defect model, it is demonstrated that GMAP microspheres significantly improve bone regeneration, as verified by micro-computed tomography and histological examinations. This study provides a novel strategy for bone regeneration by modulating the diabetic microenvironment, presenting a promising approach for addressing the complex challenges associated with bone healing in diabetic patients.

Short- and long-term exposure to high glucose induces unique transcriptional changes in osteoblasts in vitro

Bone is increasingly recognized as a target for diabetic complications. In order to evaluate the direct effects of high glucose on bone, we investigated the global transcriptional changes induced by hyperglycemia in osteoblasts in vitro. Rat bone marrow-derived mesenchymal stromal cells were differentiated into osteoblasts for 10 days, and prior to analysis, they were exposed to hyperglycemia (25 mM) for the short-term (1 or 3 days) or long-term (10 days). Genes and pathways regulated by hyperglycemia were identified using mRNA sequencing and verified with qPCR. Genes upregulated by 1-day hyperglycemia were, for example, related to extracellular matrix organization, collagen synthesis and bone formation. This stimulatory effect was attenuated by 3 days. Long-term exposure impaired osteoblast viability, and downregulated, for example, extracellular matrix organization and lysosomal pathways, and increased intracellular oxidative stress. Interestingly, transcriptional changes by different exposure times were mostly unique and only 89 common genes responding to glucose were identified. In conclusion, short-term hyperglycemia had a stimulatory effect on osteoblasts and bone formation, whereas long-term hyperglycemia had a negative effect on intracellular redox balance, osteoblast viability and function.

Diabetic Rats Induced Using a High-Fat Diet and Low-Dose Streptozotocin Treatment Exhibit Gut Microbiota Dysbiosis and Osteoporotic Bone Pathologies

Type 2 diabetes mellitus (T2DM) presents a challenge for individuals today, affecting their health and life quality. Besides its known complications, T2DM has been found to contribute to bone/mineral abnormalities, thereby increasing the vulnerability to bone fragility/fractures. However, there is still a need for appropriate diagnostic approaches and targeted medications to address T2DM-associated bone diseases. This study aims to investigate the relationship between changes in gut microbiota, T2DM, and osteoporosis. To explore this, a T2DM rat model was induced by combining a high-fat diet and low-dose streptozotocin treatment. Our findings reveal that T2DM rats have lower bone mass and reduced levels of bone turnover markers compared to control rats. We also observe significant alterations in gut microbiota in T2DM rats, characterized by a higher relative abundance of Firmicutes (F) and Proteobacteria (P), but a lower relative abundance of Bacteroidetes (B) at the phylum level. Further analysis indicates a correlation between the F/B ratio and bone turnover levels, as well as between the B/P ratio and HbA1c levels. Additionally, at the genus level, we observe an inverse correlation in the relative abundance of Lachnospiraceae. These findings show promise for the development of new strategies to diagnose and treat T2DM-associated bone diseases.

Association of sarcopenia with osteoporosis in Chinese patients with type 2 diabetes

BACKGROUND

People with type 2 diabetes mellitus (T2DM) present a higher tendency to develop sarcopenia and osteoporosis compared with the normal population. Currently, osteoporosis screening has been frequently performed among T2DM patients, but sarcopenia screening is relatively less, and the association between the two diseases remains unclear. Herein, this study aims to determine the association between sarcopenia and osteoporosis in Chinese T2DM patients.

METHODS

This was a retrospective study of 678 patients with T2DM in the First Affiliated Hospital of Wenzhou Medical University. The bone mineral density (BMD) and muscle mass were measured by using dual-energy X-ray absorptiometry scanning. The diagnostic criteria of sarcopenia referred to the consensus by the Asia Working Group for Sarcopenia (AWGS).

RESULT

Among T2DM patients, the proportion of the sarcopenia population complicated with osteoporosis was higher than that of the non-sarcopenia (30.9% vs. 8.6% in men and 46.9% vs. 33.9% in women), but only significantly in men. The BMD of the hip and femoral neck was positively correlated with skeletal muscle mass index (SMI), grip strength, and gait speed (P < 0.01). After adjusting all covariates, the association between sarcopenia and BMD showed odds ratios of 0.43 (95% CI:0.28-0.66) for the femoral neck and 0.49 (95% CI:0.32-0.73) for the hip.

CONCLUSIONS

The BMD of the hip and femoral neck in T2DM patients is related to sarcopenia-related indicators and represents an independent protective factor for sarcopenia. To reduce the risk of falls, fractures, and weakness, it is necessary to take sarcopenia assessment in people with T2DM and osteopenia/osteoporosis.

Epigenetic changes underlie the association between diabetes mellitus and oral diseases

Patients with diabetes mellitus (DM) suffer from oral complications related to oral infections, periodontal diseases, and endodontic lesions. Emerging evidence has revealed the contribution of the epigenetic process as the underlying mechanism of DM complications. DNA methylation, histone modifications, and non-coding RNAs are epigenetic regulators that directly affect gene expression. The present review elaborated on the role of epigenetic dysregulation in the etiology of diabetes-related periodontal and endodontic diseases. The narrative review study was prepared using databases such as PubMed, Google Scholar, Science Direct, and Scopus. The formation of glycation products as a result of hyperglycemic condition increases oxidative stress, and elevates chronic inflammatory mediators that could in turn adversely change the cellular environment and alter the epigenetic status. This process contributes to the alteration of regulatory genes expression, leading to the development of diabetes-induced bone complications and impaired odontogenic capacity of pulp. Indeed, epigenetic mechanisms mediate the interaction between gene expression and DM cellular environment. Further investigations on epigenetic factors involved in DM oral complications may provide novel therapeutic targets.

Reduced High-Density Lipoprotein Cholesterol Is an Independent Determinant of Altered Bone Quality in Women with Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is associated with an increased fracture risk. Our study aimed to explore differences in bone alterations between T2DM women and controls and to assess clinical predictors of bone impairment in T2DM. For this observational case control study, we recruited 126 T2DM female patients and 117 non-diabetic, age- and BMI-comparable women, who underwent clinical examination, routine biochemistry and dual-energy X-ray absorptiometry (DXA) scans for bone mineral density (BMD) and trabecular bone score (TBS) assessment-derived indexes. These were correlated to metabolic parameters, such as glycemic control and lipid profile, by bivariate analyses, and significant variables were entered in multivariate adjusted models to detect independent determinants of altered bone status in diabetes. The T2DM patients were less represented in the normal bone category compared with controls (5% vs. 12%; p = 0.04); T2DM was associated with low TBS (OR: 2.47, C.I. 95%: 1.19–5.16, p = 0.016) in a regression model adjusted for age, menopausal status and BMI. In women with T2DM, TBS directly correlated with plasma high-density lipoprotein cholesterol (HDL-c) (p = 0.029) and vitamin D (p = 0.017) levels. An inverse association was observed with menopausal status (p < 0.001), metabolic syndrome (p = 0.014), BMI (p = 0.005), and waist circumference (p < 0.001). In the multivariate regression analysis, lower HDL-c represented the main predictor of altered bone quality in T2DM, regardless of age, menopausal status, BMI, waist circumference, statin treatment, physical activity, and vitamin D (p = 0.029; R2 = 0.47), which likely underlies common pathways between metabolic disease and bone health in diabetes.

Advanced Glycation End Products Effects on Adipocyte Niche Stiffness and Cell Signaling

Adipose tissue metabolism under hyperglycemia results in Type II diabetes (T2D). To better understand how the adipocytes function, we used a cell culture that was exposed to glycation by adding intermediate carbonyl products, which caused chemical cross-linking and led to the formation of advanced glycation end products (AGEs). The AGEs increased the cells and their niche stiffness and altered the rheological viscoelastic properties of the cultured cells leading to altered cell signaling. The AGEs formed concomitant with changes in protein structure, quantified by spectroscopy using the 8-ANS and Nile red probes. The AGE effects on adipocyte differentiation were viewed by imaging and evidenced in a reduction in cellular motility and membrane dynamics. Importantly, the alteration led to reduced adipogenesis, that is also measured by qPCR for expression of adipogenic genes and cell signaling. The evidence of alteration in the plasma membrane (PM) dynamics (measured by CTxB binding and NP endocytosis), also led to the impairment of signal transduction and a decrease in AKT phosphorylation, which hindered downstream insulin signaling. The study, therefore, presents a new interpretation of how AGEs affect the cell niche, PM stiffness, and cell signaling leading to an impairment of insulin signaling.

Annexin A2 Improves the Osteogenic Differentiation of Mesenchymal Stem Cells Exposed to High-Glucose Conditions through Lessening the Senescence

Osteoporosis is frequently found in chronic diabetic patients, and it results in an increased risk of bone fractures occurring. The underlying mechanism of osteoporosis in diabetic patients is still largely unknown. Annexin A2 (ANXA2), a family of calcium-binding proteins, has been reported to be involved in many biological process including bone remodeling. This study aimed to investigate the role of ANXA2 in mesenchymal stem cells (MSCs) during in vitro osteoinduction under high-glucose concentrations. Osteogenic gene expression, calcium deposition, and cellular senescence were determined. The high-glucose conditions reduced the osteogenic differentiation potential of the MSCs along with the lower expression of ANXA2. Moreover, the high-glucose conditions increased the cellular senescence of the MSCs as determined by senescence-associated β-galactosidase staining and the expression of p16, p21, and p53 genes. The addition of recombinant ANXA2 could recover the glucose-induced deterioration of the osteogenic differentiation of the MSCs and ameliorate the glucose-induced cellular senescence of the MSCs. A Western blot analysis revealed an increase in p53 and phosphorylated p53 (Ser 15), which was decreased by recombinant ANXA2 in MSC osteoblastic differentiation under high-glucose conditions. Our study suggested that the alteration of ANXA2 in high-glucose conditions may be one of the plausible factors in the deterioration of bones in diabetic patients by triggering cellular senescence.

Impaired dental implant osseointegration in rat with streptozotocin-induced diabetes

OBJECTIVE

Few studies have reported on the impact of oxidative stress on the dental implant failure. The aim of this study was to investigate the impact of hyperglycemia-induced oxidative stress on dental implant osseointegration in diabetes mellitus (DM).

METHODS

Acid-treated titanium implants were bilaterally placed in the maxillary alveolar ridge of streptozotocin-induced diabetic (DM group) and control rats after extraction of first molars. Histological analysis and micro-push-out test were performed 4 weeks after surgery. Oxidative stress and osteogenic markers in the surrounding bone were quantified by real-time polymerase chain reaction. In the in vitro study, rat bone marrow-derived mesenchymal stem cells (BMMSCs) were cultured on acid-treated titanium discs in a high-glucose (HG) or normal environment. Intracellular reactive oxygen species (ROS), cell proliferation, alkaline phosphatase (ALP) activity, and extracellular calcification were evaluated following antioxidant treatment with N-acetyl-L-cysteine (NAC).

RESULTS

The implant survival rate was 92.9% and 75.0% in control and DM group, respectively. Bone-implant contact and push-out loads were significantly lower in the DM group. Expression of superoxide dismutase 1 at the mRNA level and on immunohistochemistry was significantly lower in the DM group. In vitro experiments revealed that the HG condition significantly increased ROS expression and suppressed the proliferation and extracellular calcification of BMMSCs, while NAC treatment significantly restored ROS expression, cell proliferation, and calcification. The ALP activity of both groups was not significantly different.

CONCLUSION

In diabetes, high-glucose-induced oxidative stress downregulates proliferation and calcification of BMMSCs, impairing osseointegration and leading to implant failure.

Circulating osteogenic progenitors and osteoclast precursors are associated with long-term glycemic control, sex steroids, and visceral adipose tissue in men with type 2 diabetes mellitus

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is well-known to be associated with normal bone density but, concurrently, low bone turnover and increased risk for fracture. One of the proposed mechanisms is possible derangement in bone precursor cells, which could be represented by deficiencies in circulating osteogenic progenitor (COP) cells and osteoclast precursors (OCP). The objective of our study is to understand whether extent of glycemic control has an impact on these cells, and to identify other factors that may as well.

METHODS

This was a secondary analysis of baseline data from 51 male participants, aged 37-65 in an ongoing clinical trial at Michael E. DeBakey VA Medical Center, Houston, Texas, USA. At study entry serum Hemoglobin A1c was measured by high-performance liquid chromatography osteocalcin (OCN) and C-terminal telopeptide of type 1 collagen (CTx) were measured by ELISA, and testosterone and estradiol by liquid-chromatography/mass-spectrometry. Areal bone mineral density (BMD), trabecular bone score and body composition were measured by dual energy x-ray absorptiometry, while COP and OCP were measured by flow cytometry.

RESULTS

When adjusted for serum testosterone, parathyroid hormone, and 25-hydroxyvitamin D, those with poor long-term glycemic control had significantly higher percentage of COP (p = 0.04). COP correlated positively with visceral adipose tissue (VAT) volume (r = 0.37, p = 0.01) and negatively with free testosterone (r = -0.28, p = 0.05) and OCN (r = -0.28, p = 0.07), although only borderline for the latter. OCP correlated positively with age, FSH, lumbar spine BMD, and COP levels, and negatively with glucose, triglycerides, and free estradiol. Multivariable regression analyses revealed that, in addition to being predictors for each other, another independent predictor for COP was VAT volume while age, glucose, and vitamin D for OCP.

CONCLUSION

Our results suggest that high COP could be a marker of poor metabolic control. However, given the complex nature and the multitude of factors influencing osteoblastogenesis/adipogenesis, it is possible that the increase in COP is a physiologic response of the bone marrow to increased osteoblast apoptosis from poor glycemic control. Alternatively, it is also likely that a metabolically unhealthy profile may retard the development of osteogenic precursors to fully mature osteoblastic cells.

Effects of Incretin-Related Diabetes Drugs on Bone Formation and Bone Resorption

Patients with type 2 diabetes have an increased risk of fracture compared to the general population. Glucose absorption is accelerated by incretin hormones, which induce insulin secretion from the pancreas. The level of the incretin hormone, glucagon-like peptide-1 (GLP-1), shows an immediate postprandial increase, and the circulating level of intact GLP-1 is reduced rapidly by dipeptidyl peptidase-4 (DPP-4)-mediated inactivation. Therefore, GLP-1 receptor agonists and DPP-4 inhibitors are effective in the treatment of type 2 diabetes. However, these incretin-related diabetic agents have been reported to affect bone metabolism, including bone formation and resorption. These agents enhance the expression of bone markers, and have been applied to improve bone quality and bone density. In addition, they have been reported to suppress chronic inflammation and reduce the levels of inflammatory cytokine expression. Previously, we reported that these incretin-related agents inhibited both the expression of inflammatory cytokines and inflammation-induced bone resorption. This review presents an overview of current knowledge regarding the effects of incretin-related diabetes drugs on osteoblast differentiation and bone formation as well as osteoclast differentiation and bone resorption. The mechanisms by which incretin-related diabetes drugs regulate bone formation and bone resorption are also discussed.

Antioxidant Sirt1/Akt axis expression in resveratrol pretreated adipose-derived stem cells increases regenerative capability in a rat model with cardiomyopathy induced by diabetes mellitus

High-glucose (HG) suppresses mesenchymal stem cell (MSC) functions, resulting in a decrease in cardiac regenerative capability for MSC in diabetes mellitus (DM). Resveratrol enhances MSC functions under stress. This study explores if cardiac regenerative capability can be enhanced in MSCs pretreated with resveratrol in DM rats receiving MSCs. In vitro evidence confirms that HG decreases MSCs capability through suppression of survival markers, AMP-activated protein kinase (AMPK)/Sirtuin 1 (Sirt1) axis, and expression of apoptotic markers. All of these markers are improved when MSCs are cocultured with resveratrol. Wistar male rats were randomly divided into Sham, DM (DM rats), DM rats with autologous transplantation of adipose-derived stem cells (DM + ADSC), and DM rats with resveratrol pretreated ADSC (DM + RSVL-ADSC). Compared to the Sham, DM induces pathological pathways (including fibrosis, hypertrophy, and apoptosis) and suppresses survival as well as the AMPK/Sirt1 axis in the DM group. DM + ADSC slightly improves the above pathways whereas DM + RSVL-ADSC significantly improves the above pathways when compared to the DM group. These results illustrate that resveratrol pretreated with MSCs may show clinical potential in the treatment of heart failure in patients with DM.

Exploring the Mechanism of Total Flavonoids of Drynariae Rhizoma to Improve Large Bone Defects by Network Pharmacology and Experimental Assessment

Drynariae Rhizoma (DR) has been demonstrated to be effective in promoting fracture healing in clinical use. In the study, we tried to predicate potential signaling pathways and active ingredients of DR via network pharmacology, uncover its regulation mechanism to improve large bone defects by in vivo and in vitro experiment. We total discovered 18 potential active ingredients such as flavonoids and 81 corresponding targets, in which mitogen-activated protein kinase (MAPK) signaling pathway has the highest correlation with bone defects in pathway and functional enrichment analysis. Therefore, we hypothesized that flavonoids in DR improve large bone defects by activating MAPK signaling pathway. Animal experiments were carried out and all rats randomly divided into TFDR low, medium, and high dosage group, model group and control group. 12 weeks after treatment, according to X-ray and Micro-CT, TFDR medium dosage group significantly promote new bone mineralization compared with other groups. The results of HE and Masson staining and in vitro ALP level of BMSC also demonstrated the formation of bone matrix and mineralization in the TFDR groups. Also, angiographic imaging suggested that flavonoids in DR promoting angiogenesis in the defect area. Consistently, TFDR significantly enhanced the expression of BMP-2, RUNX-2, VEGF, HIF-1 in large bone defect rats based on ELISA and Real-Time PCR. Overall, we not only discover the active ingredients of DR in this study, but also explained how flavonoids in DR regulating MAPK signaling pathway to improve large bone defects.

Enhanced Osteogenic Differentiation of Pluripotent Stem Cells via γ-Secretase Inhibition

Bone healing is a complex, well-organized process. Multiple factors regulate this process, including growth factors, hormones, cytokines, mechanical stimulation, and aging. One of the most important signaling pathways that affect bone healing is the Notch signaling pathway. It has a significant role in controlling the differentiation of bone mesenchymal stem cells and forming new bone. Interventions to enhance the healing of critical-sized bone defects are of great importance, and stem cell transplantations are eminent candidates for treating such defects. Understanding how Notch signaling impacts pluripotent stem cell differentiation can significantly enhance osteogenesis and improve the overall healing process upon transplantation. In Rancourt’s lab, mouse embryonic stem cells (ESC) have been successfully differentiated to the osteogenic cell lineage. This study investigates the role of Notch signaling inhibition in the osteogenic differentiation of mouse embryonic and induced pluripotent stem cells (iPS). Our data showed that Notch inhibition greatly enhanced the differentiation of both mouse embryonic and induced pluripotent stem cells.

Semaphorin3B Promotes Proliferation and Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells in a High-Glucose Microenvironment

Bone marrow mesenchymal stem cells (BMSCs) play an essential role in osteogenesis and bone metabolism and have already been recognized as one of the most popular seed cells for bone tissue engineering for bone diseases. However, high-glucose (HG) conditions in type 2 diabetes mellitus (T2DM) exert deleterious effects on BMSC proliferation and osteogenic differentiation. Semaphorin 3B (Sema3B) increases osteoblast differentiation in bone metabolism. Here, we determined the role of Sema3B in the proliferation and osteogenic differentiation of BMSCs in the HG microenvironment. The HG microenvironment decreased Sema3B expression in BMSCs. Moreover, HG inhibited BMSC proliferation. Furthermore, HG inhibited osteogenic differentiation in BMSCs by decreasing the expression of bone formation markers, alkaline phosphatase (ALP) activity, and mineralization. However, the administration of recombinant Sema3B reversed all of these effects. Moreover, our study found that Sema3B could activate the Akt pathway in BMSCs. Sema3B rescues defects in BMSC proliferation and osteogenic differentiation in the HG microenvironment by activating the Akt pathway. These effects were significantly reduced by treatment with an Akt inhibitor. Together, these findings demonstrate that Sema3B promotes the proliferation and osteogenic differentiation of BMSCs via the Akt pathway under HG conditions. Our study provides new insights into the potential ability of Sema3B to ameliorate BMSC proliferation and osteogenic differentiation in an HG microenvironment.

High glucose inhibits osteogenic differentiation of bone marrow mesenchymal stem cells via regulating miR-493-5p/ZEB2 signalling

Diabetic osteoporosis (DOP) is attributed to the aberrant physiological function of bone marrow mesenchymal stem cells (BMSCs) under high glucose (HG) environment. MicroRNAs (miRNAs) are involved in the pathological processes of DOP. We aimed to explore the underlying mechanism of miRNA in DOP. BMSCs were cultured in osteogenic medium with HG to induce osteogenic differentiation, and the interaction between miR-493-5p and ZEB2 was assessed by luciferase assay. Herein, we found miR-493-5p is gradually reduced during osteogenic differentiation in BMSCs. HG treatment inhibits osteogenic differentiation and induces an up-regulation of miR-493-5p leading to reduced level of its downstream target ZEB2. Inhibition of miR-493-5p attenuates HG-induced osteogenic differentiation defects by upregulation of ZEB2. Mechanistically, miR-493-5p/ZEB2 signalling mediates HG-inhibited osteogenic differentiation by inactivation of Wnt/β-catenin signalling. More importantly, knockdown of miR-493-5p therapeutically alleviated the DOP condition in mice. HG prevents BMSCs osteogenic differentiation via up-regulation of miR-493-5p, which results in reduced level of ZEB2 by directly targeting its 3'-untranslated region of mRNA. Thus, miR-493-5p/ZEB2 is a potential therapeutic target and provides novel strategy for the treatment and management of DOP.

Correlation of Osteoporosis in Patients With Newly Diagnosed Type 2 Diabetes: A Retrospective Study in Chinese Population

This study aimed to explore the risk factors attributed to osteoporosis in newly type 2 diabetes mellitus (T2DM) patients. This study aimed to recruit 244 T2DM patients and 218 non-diabetic controls. We collected demographic characteristics, medical history, bone mineral density and biomarkers including bone specific alkaline phosphatase (BALP), osteocalcin, N-terminal peptide of type I procollagen (P1NP), tartrate-resistant acid phosphatase 5b (TRCAP-5b), β-Cross Laps of type I collagen-containing cross-linked C-telopeptide (β-CTX), 25-hydroxyvitamin D, parathyroid hormone were recorded or detected. Bone mineral density (BMD) was our primary outcome. Based on the result of BMD, we divided both the control group and T2DM group into three subgroups: normal bone mass, osteopenia and osteoporosis. In control group, we found age, sex, menopausal status, BMI, P1NP, BALP, TRACP-5b, osteocalcin, and corrected serum calcium are differential among three subgroups. In T2DM group, we found age, sex, menopausal status, drinking status, BMI, HbA1c, TRACP-5b and OC were differential among three subgroups. In T2DM and control groups, age, female, postmenopausal status, BALP, TRACP-5b and osteocalcin were positively correlated while BMI was negatively correlated with osteoporosis. In control group, β-CTX was positively correlated with osteoporosis. In T2DM group, HbA1c and corrected serum calcium concentration were positively correlated with osteoporosis. After further adjustment of age, BMI in male, TRACP-5b was positively correlated with the risk of osteoporosis in newly diagnosed T2DM. After adjusted of age, BMI and menopausal status in female, OC was positively correlated with the risk of osteoporosis in newly diagnosed T2DM and controls. In female T2DM, BALP and P1NP were positively correlated with the risk of osteoporosis. In conclusion, age, BMI and menopausal status are common risk factors for osteoporosis in diabetic and non-diabetic patients, however TRACP-5b, BALP and osteocalcin are special risk factors for osteoporosis in newly diagnosed T2DM patients but not non-diabetic patients, which may be applied to identify osteoporosis risk in T2DM patients, but this result needs to be proven with fracture data.

Parathyroid hormone ameliorates osteogenesis of human bone marrow mesenchymal stem cells against glucolipotoxicity through p38 MAPK signaling

Diabetes mellitus (DM)-induced glucolipotoxicity is a factor strongly contributing to alveolar bone deficiency. Parathyroid hormone (PTH) has been identified as a main systemic mediator to balance physiological calcium in bone. This study aimed to uncover PTH's potential role in ameliorating the osteogenic capacity of human bone marrow mesenchymal stem cells (HBMSCs) against glucolipotoxicity. Optimal PTH concentrations and high glucose and palmitic acid (GP) were administered to cells, followed by alkaline phosphatase (ALP) staining and ALP activity assay. Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and Immunoblot were carried out for assessing mRNA and protein amounts, respectively. Cell counting kit-8 (CCK-8) and flow cytometry were performed for quantitating cell proliferation. Osteogenesis and oxidative stress were determined, and the involvement of mitogen-activated protein kinase (MAPK) signaling was further verified. About 1-50 mmol/ml GP significantly inhibited the osteogenic differentiation of HBMSCs. 10^-9 mol/L PTH was found to be the optimal concentration for HBMSC induction. PTH had no effects on HBMSC proliferation, with or without GP treatment. PTH reversed inadequate osteogenesis and excessive oxidative stress in GP-treated HBMSCs. Mechanistically, PTH activated p38 MAPK signaling, while inhibiting p38 MAPK-suppressed PTH's beneficial impacts on HBMSCs. Collectively, PTH promotes osteogenic differentiation in HBMSCs against glucolipotoxicity via p38 MAPK signaling.

Proteomic study of in vitro osteogenic differentiation of mesenchymal stem cells in high glucose condition

Patients with diabetes have been widely reported to be at an increased risk of secondary osteoporosis. Osteoporosis is caused by an imbalance in bone remodeling due to increased bone resorption and/or decreased osteoblast-dependent bone formation. In this study, mesenchymal stem cells (MSCs) were used as a disease model to determine the effects of high glucose levels on MSC-osteoblast development. The results indicated that under high glucose conditions, MSCs had reduced cell viability and increased number of β-galactosidase-positive cells. Furthermore, in vitro osteogenesis was shown to be reduced in MSCs cultured in osteogenic differentiation medium at 10, 25, and 40 mM glucose as demonstrated by Alizarin red S staining and alkaline phosphatase activity assay. Moreover, a proteomic study was performed in MSCs cultured with 25 and 40 mM glucose. The proteomic results demonstrated that 12 proteins were up- and downregulated in bone marrow-derived mesenchymal stem cells cultured with high glucose in a dose-dependent manner. The findings presented here contribute to our understanding of the mechanism of diabetes mellitus responsible for bone loss. However, the exact mechanism of action of hyperglycemia on bone deformability requires additional studies.

Bone marrow fat: friend or foe in people with diabetes mellitus?

Global trends in the prevalence of overweight and obesity put the adipocyte in the focus of huge medical interest. This review highlights a new topic in adipose tissue biology, namely the emerging pathogenic role of fat accumulation in bone marrow (BM). Specifically, we summarize current knowledge about the origin and function of BM adipose tissue (BMAT), provide evidence for the association of excess BMAT with diabetes and related cardiovascular complications, and discuss potential therapeutic approaches to correct BMAT dysfunction. There is still a significant uncertainty about the origins and function of BMAT, although several subpopulations of stromal cells have been suggested to have an adipogenic propensity. BM adipocytes are higly plastic and have a distinctive capacity to secrete adipokines that exert local and endocrine functions. BM adiposity is abundant in elderly people and has therefore been interpreted as a component of the whole-body ageing process. BM senescence and BMAT accumulation has been also reported in patients and animal models with Type 2 diabetes, being more pronounced in those with ischaemic complications. Understanding the mechanisms responsible for excess and altered function of BMAT could lead to new treatments able to preserve whole-body homeostasis.

Expression of Notch family is altered in non‑alcoholic fatty liver disease

The aim of the present study was to explore the dynamic relationship between Notch and non‑alcoholic fatty liver disease (NAFLD), both in vitro and in vivo. The LX2, Huh7 and MIHA hepatic cell lines were used to establish a cell steatosis model induced by palmitic acid (PA) at different concentrations (0.1, 0.25 and 0.5 mM). Cell proliferation and migration were assessed using a 5‑bromo‑2'‑deoxyuridine kit and a wound healing assay. The dosage of 0.25 mM PA for 36‑48 h treatment was chosen for subsequent experiments. Steatotic cells were identified by Oil Red O staining. Feeding mice a methionine‑choline‑deficient (MCD) diet is known induce a model of NAFLD, compared with a methionine‑choline‑sufficient (MCS) diet. Therefore, Notch family mRNA expression was evaluated in the liver of MCD‑fed mice at varying time points (days 5, 10, 21 and 70) using reverse transcription‑quantitative PCR. Notch expression levels were also assessed in cell lines at 12, 24, 36 and 48 h after PA treatment. Notch signaling molecules changed in the PA or MCD model over time. In vitro, the mRNA levels of Notch1, ‑2 and ‑4 increased in all cell lines after 12‑h PA treatment. At 24 h, these genes were upregulated only in LX2 cells, while showing a 'down‑up' pattern in MIHA cells (i.e. these genes were downregulated at 24 h but upregulated at 36 h). However, expression of Notch1, ‑2, ‑3 and ‑4 mRNA rose significantly in the early stage (day 10) of NAFLD. At week 3, the levels of Notch1 and ‑2 were higher in the MCD group than in the MCS group, while the reverse was observed for Notch3 and ‑4. Expression of these four genes increased again in the late stage (day 70) of NAFLD. Therefore, these results indicated that Notch family members Notch1‑4 were involved in the development of NAFLD and played an important role in steatosis in this model.

Impact of Type 2 Diabetes Mellitus on Human Bone Marrow Stromal Cell Number and Phenotypic Characteristics

Human bone marrow-derived mesenchymal stromal cells (MSCs) have been investigated in numerous disease settings involving impaired regeneration because of the crucial role they play in tissue maintenance and repair. Considering the number of comorbidities associated with type 2 diabetes mellitus (T2DM), the hypothesis that MSCs mediate these comorbidities via a reduction in their native maintenance and repair activities is an intriguing line of inquiry. Here, it is demonstrated that the number of bone marrow-derived MSCs in people with T2DM was reduced compared to that of age-matched control (AMC) donors and that this was due to a specific decrease in the number of MSCs with osteogenic capacity. There were no differences in MSC cell surface phenotype or in MSC expansion, differentiation, or angiogenic or migratory capacity from donors living with T2DM as compared to AMCs. These findings elucidate the basic biology of MSCs and their potential as mediators of diabetic comorbidities, especially osteopathies, and provide insight into donor choice for MSC-based clinical trials. This study suggests that any role of bone marrow MSCs as a mediator of T2DM comorbidity is likely due to a reduction in the osteoprogenitor population size and not due to a permanent alteration to the MSCs' capacity to maintain tissue homeostasis through expansion and differentiation.

Current Knowledge Regarding the Interaction Between Oral Bone Metabolic Disorders and Diabetes Mellitus

Diabetes mellitus, a major chronic disease affecting human health, has been increasing in prevalence in recent years. Diabetes mellitus can cause bone metabolic disorders in patients, leading to osteoporosis, a higher risk of traumatic fracture, and other bone diseases. Bone metabolic disorders in the oral cavity principally manifest as periodontitis, loss of alveolar bone, and failure of implant osseointegration. In recent years, numerous studies have shown that there is a complex interaction between bone metabolic disorders and diabetes mellitus. This paper reviews the adverse effects of diabetes on oral bone metabolism disorders such as alveolar osteoporosis and bone loss in patients with periodontitis, discusses the potential mechanisms of diabetic bone loss, and suggests potential ways to prevent and treat oral bone loss in patients with diabetes mellitus.

Impact of Diabetes Mellitus on Bone Health

Long-term exposure to a diabetic environment leads to changes in bone metabolism and impaired bone micro-architecture through a variety of mechanisms on molecular and structural levels. These changes predispose the bone to an increased fracture risk and impaired osseus healing. In a clinical practice, adequate control of diabetes mellitus is essential for preventing detrimental effects on bone health. Alternative fracture risk assessment tools may be needed to accurately determine fracture risk in patients living with diabetes mellitus. Currently, there is no conclusive model explaining the mechanism of action of diabetes mellitus on bone health, particularly in view of progenitor cells. In this review, the best available literature on the impact of diabetes mellitus on bone health in vitro and in vivo is summarised with an emphasis on future translational research opportunities in this field.