Investigation for GSK3β expression in diabetic osteoporosis and negative osteogenic effects of GSK3β on bone marrow mesenchymal stem cells under a high glucose microenvironment

Unraveling the mechanism in l-Caldesmon regulating the osteogenic differentiation of PDLSCs: An innovative perspective

Maxillofacial bone defect is one of the common symptoms in maxillofacial, which affects the function and aesthetics of maxillofacial region. Periodontal ligament stem cells (PDLSCs) are extensively used in bone tissue engineering. The mechanism that regulates the osteogenic differentiation of PDLSCs remains not fully elucidated. Previous studies demonstrated that l-Caldesmon (l-CALD, or CALD1) might be involved in the osteogenic differentiation of PDLSCs. Here, the mechanism by which CALD1 regulates the osteogenic differentiation of PDLSCs is investigated. The osteogenic differentiation of PDLSCs is enhanced with Cald1 knockdown. Whole transcriptome sequencing (RNA-seq) analysis shows that bone morphogenetic proteins (BMP) signaling pathway and Wingless type (Wnt) pathway have significant change with Cald1 knockdown, and the expressions of Wnt-induced secreted protein 1 (WISP1), BMP2, Smad1/5/9, and p-Smad1/5/9 are significantly upregulated, while Glycogen synthase kinase 3β (GSK3β) and p-GSK3β are downregulated. In addition, subcutaneous implantation in nude mice shows that knockdown of Cald1 enhances the osteogenic differentiation of PDLSCs in vivo. Taken together, this study demonstrates that knockdown of Cald1 enhances the osteogenic differentiation of PDLSCs by BMP and Wnt signaling pathways, and provides a novel approach for subsequent clinical treatment.

3D printing and bioprinting in the battle against diabetes and its chronic complications

Diabetes is a metabolic disorder characterized by high blood sugar. Uncontrolled blood glucose affects the circulatory system in an organism by intervening blood circulation. The high blood glucose can lead to macrovascular (large blood vessels) and microvascular (small blood vessels) complications. Due to this, the vital organs (notably brain, eyes, feet, heart, kidneys, lungs and nerves) get worsen in diabetic patients if not treated at the earliest. Therefore, acquiring treatment at an appropriate time is very important for managing diabetes and other complications that are caused due to diabetes. The root cause for the occurrence of various health complications in diabetic patients is the uncontrolled blood glucose levels. This review presents a consolidated account of the applications of various types of three-dimensional (3D) printing and bioprinting technologies in treating diabetes as well as the complications caused due to impaired blood glucose levels. Herein, the development of biosensors (for the diagnosis), oral drug formulations, transdermal drug carriers, orthotic insoles and scaffolds (for the treatment) are discussed. Next to this, the fabrication of 3D bioprinted organs and cell-seeded hydrogels (pancreas engineering for producing insulin and bone engineering for managing bone defects) are explained. As the final application, 3D bioprinting of diabetic disease models for high-throughput screening of ant-diabetic drugs are discussed. Lastly, the challenges and future perspective associated with the use of 3D printing and bioprinting technologies against diabetes and its related chronic complications have been put forward.

Bone canonical Wnt signaling is downregulated in type 2 diabetes and associates with higher advanced glycation end-products (AGEs) content and reduced bone strength

Type 2 diabetes (T2D) is associated with higher fracture risk, despite normal or high bone mineral density. We reported that bone formation genes (SOST and RUNX2) and advanced glycation end-products (AGEs) were impaired in T2D. We investigated Wnt signaling regulation and its association with AGEs accumulation and bone strength in T2D from bone tissue of 15 T2D and 21 non-diabetic postmenopausal women undergoing hip arthroplasty. Bone histomorphometry revealed a trend of low mineralized volume in T2D (T2D 0.249% [0.156-0.366]) vs non-diabetic subjects 0.352% [0.269-0.454]; p=0.053, as well as reduced bone strength (T2D 21.60 MPa [13.46-30.10] vs non-diabetic subjects 76.24 MPa [26.81-132.9]; p=0.002). We also showed that gene expression of Wnt agonists LEF-1 (p=0.0136) and WNT10B (p=0.0302) were lower in T2D. Conversely, gene expression of WNT5A (p=0.0232), SOST (p<0.0001), and GSK3B (p=0.0456) were higher, while collagen (COL1A1) was lower in T2D (p=0.0482). AGEs content was associated with SOST and WNT5A (r=0.9231, p<0.0001; r=0.6751, p=0.0322), but inversely correlated with LEF-1 and COL1A1 (r=-0.7500, p=0.0255; r=-0.9762, p=0.0004). SOST was associated with glycemic control and disease duration (r=0.4846, p=0.0043; r=0.7107, p=0.00174), whereas WNT5A and GSK3B were only correlated with glycemic control (r=0.5589, p=0.0037; r=0.4901, p=0.0051). Finally, Young's modulus was negatively correlated with SOST (r=-0.5675, p=0.0011), AXIN2 (r=-0.5523, p=0.0042), and SFRP5 (r=-0.4442, p=0.0437), while positively correlated with LEF-1 (r=0.4116, p=0.0295) and WNT10B (r=0.6697, p=0.0001). These findings suggest that Wnt signaling and AGEs could be the main determinants of bone fragility in T2D.

Proteomic Analysis of the Supernatant from Bone Marrow Mesenchymal Stem Cells under High Glucose Conditions

Diabetes mellitus hinders the process of bone regeneration by inhibiting the function of mesenchymal stem cells (MSCs) through elevated glucose levels, thereby impeding osteointegration. The stem cell niche (SCN) plays a crucial role in determining the fate of stem cells by integrating various signals. However, the precise mechanism by which high glucose levels affect the SCN and subsequently influence the function of MSCs remains unclear. In this study, we employed proteomic analysis to identify proteins with altered expression in the extracellular matrix (ECM), aiming to elucidate the underlying mechanism. Three cell supernatants were collected from bone marrow mesenchymal stem cells (BMSCs) or BMSCs stimulated with high glucose (BMSCs+Hg). A total of 590 differentially expressed proteins were identified, which were found to be associated with the ECM, including aging, autophagy, and osteogenic differentiation. The findings of our study indicate that elevated glucose levels exert an influence on the molecular aspects of the SCN, potentially contributing to a better comprehension of the underlying mechanism.

Osteogenesis of bone marrow mesenchymal stem cell in hyperglycemia

Diabetes mellitus (DM) has been shown to be a clinical risk factor for bone diseases including osteoporosis and fragility. Bone metabolism is a complicated process that requires coordinated differentiation and proliferation of bone marrow mesenchymal stem cells (BMSCs). Owing to the regenerative properties, BMSCs have laid a robust foundation for their clinical application in various diseases. However, mounting evidence indicates that the osteogenic capability of BMSCs is impaired under high glucose conditions, which is responsible for diabetic bone diseases and greatly reduces the therapeutic efficiency of BMSCs. With the rapidly increasing incidence of DM, a better understanding of the impacts of hyperglycemia on BMSCs osteogenesis and the underlying mechanisms is needed. In this review, we aim to summarize the current knowledge of the osteogenesis of BMSCs in hyperglycemia, the underlying mechanisms, and the strategies to rescue the impaired BMSCs osteogenesis.

Iron metabolism and ferroptosis in diabetic bone loss: from mechanism to therapy

Osteoporosis, one of the most serious and common complications of diabetes, has affected the quality of life of a large number of people in recent years. Although there are many studies on the mechanism of diabetic osteoporosis, the information is still limited and there is no consensus. Recently, researchers have proven that osteoporosis induced by diabetes mellitus may be connected to an abnormal iron metabolism and ferroptosis inside cells under high glucose situations. However, there are no comprehensive reviews reported. Understanding these mechanisms has important implications for the development and treatment of diabetic osteoporosis. Therefore, this review elaborates on the changes in bones under high glucose conditions, the consequences of an elevated glucose microenvironment on the associated cells, the impact of high glucose conditions on the iron metabolism of the associated cells, and the signaling pathways of the cells that may contribute to diabetic bone loss in the presence of an abnormal iron metabolism. Lastly, we also elucidate and discuss the therapeutic targets of diabetic bone loss with relevant medications which provides some inspiration for its cure.

Enhancers of mesenchymal stem cell stemness and therapeutic potency

Mesenchymal stem cells (MSCs) are multipotent stromal cells that can differentiate into a range of cell types, including osteoblasts, chondrocytes, myocytes, and adipocytes. Multiple preclinical investigations and clinical trials employed enhanced MSCs-dependent therapies in treatment of inflammatory and degenerative diseases. They have demonstrated considerable and prospective therapeutic potentials even though the large-scale use remains a problem. Several strategies have been used to improve the therapeutic potency of MSCs in cellular therapy. Treatment of MSCs utilizing pharmaceutical compounds, cytokines, growth factors, hormones, and vitamins have shown potential outcomes in boosting MSCs' stemness. In this study, we reviewed the current advances in enhancing techniques that attempt to promote MSCs' therapeutic effectiveness in cellular therapy and stemness in vivo with potential mechanisms and applications.

Exposure to famine in every stage of life and the risk of osteoporosis and fractures later in life: A cross-sectional study

BACKGROUND AND OBJECTIVE

Data on the association between early-life famine exposure and osteoporosis and fractures remain limited and inconclusive. The aim of this study was to investigate the correlation between famine exposure and osteoporosis and fractures.

METHODS

We performed a cross-sectional analysis using the first follow-up survey data from the China Cardiometabolic Disease and Cancer Cohort Study from 2014 to 2016. We classified 4807 Lanzhou participants into seven groups based on their birthday (non-exposed or exposed in the fetal stage, early childhood, mid-childhood, late childhood, adolescence, or early adulthood). And we combined the non-exposed and early-adulthood exposed groups as a control group, which was called "age balanced group". This age-balanced group was used as the control group to further evaluate the risk of osteoporosis and fracture. We used multiple logistic regression to estimate the association between famine exposure and the risk of osteoporosis (T-score ≤ -1.8 by QUS) and self-reported fracture.

RESULTS

In women, compared to the age-balanced group, the odds ratios (95 % CI) for the risk of osteoporosis were 1.400(1.034, 1.897), 1.630(1.268, 2.095), 1.707(1.314, 2.218), 2.150(1.732.2.668) and 2.885(2.286,3.641) in the fetal stage, early childhood, mid-childhood, late childhood and adolescence famine-exposed cohorts. In men, no association between famine and osteoporosis was noted with exposed cohort compared with the age-balanced control cohort (p > 0.05). Interestingly, the association between famine exposure and fractures was slightly different from the above results: in women, the odds ratios (95 % CI) for fractures in mid-childhood famine exposure was 1.461(1.082,1.973), in late childhood famine exposure was 1.333(1.035,1.718) and in adolescence famine exposure was 1.607(1.239,2.085). However, compared to the age-balanced control cohort, men exposed to famine in early childhood (OR: 1.801, 95 % CI: 1.010,3.211) had a higher risk of fracture.

CONCLUSION

Famine exposure in different life stage has adverse effects on bone health. Famine exposure in not only the period from gestation to infancy, but also childhood and adolescence was associated with an increased risk of osteoporosis, especially in women. Exposure to famine in childhood- (mid and late) and adolescence- life period is associated with fracture in women. But, in men early-childhood famine exposure was only associated with fracture.

Transcriptomic analysis provides a new insight: Oleuropein reverses high glucose-induced osteogenic inhibition in bone marrow mesenchymal stem cells via Wnt10b activation

Adverse events of diabetes mellitus (DM) include bone damages, such as the increased incidence of osteoporosis and bone fractures, which are known as diabetic osteopathy. The pathogenic mechanism of diabetic osteopathy is complex, and hyperglycemia is a vital cause involved in it. Bone marrow mesenchymal stem cells (BMSCs) exert a significant effect on bone formation. Therefore, in this paper, transcriptomic changes of BMSCs cultured in high glucose (35 mM) for 30 days are mainly investigated. In addition, 794 up-regulated genes and 1,162 down-regulated genes were identified. Then, biological functions of the differentially expressed genes in the high glucose microenvironment were investigated by two kinds of functional analyses. Gene Set Enrichment Analysis was also applied to focus on the significant gene sets and it is found that Wnt10b expression witnessed a remarkable decrease in BMSCs under the high glucose microenvironment. At last, in vitro experiments revealed that oleuropein effectively reversed high glucose-induced osteogenic inhibition via activating Wnt10b in BMSCs.

High glucose mediates apoptosis and osteogenesis of MSCs via downregulation of AKT-Sirt1-TWIST

BACKGROUND

Mesenchymal stem cells have been widely used in the treatment of diabetes mellitus. However, hyperglycemia associated with DM promotes cell apoptosis and affects osteogenic differentiation of MSCs in varying degrees, leading to osteoporosis in DM patients. Therefore, in this paper, the effect of high glucose on apoptosis and osteogenesis of MSCs was investigated and underlying mechanism was further determined.

METHODS AND RESULTS

Intracellular ROS levels were determined using probe DCFH-DA. MMP was detected using JC-1 staining. Cell apoptosis was detected using Annexin V-FITC/PI and Flow Cytometer. The expression of genes and protein was detected by qRT-PCR and Western blot respectively. The results showed high glucose induced MSC apoptosis but promoted its osteogenesis. Western blot analysis revealed that high glucose downregulated AKT-Sirt1-TWIST pathway. Activation of Sirt1 via SRT1720 increased TWIST expression, alleviated MSC apoptosis and promoted osteogenesis of MSCs. TWIST knockdown studies demonstrated that inhibition of TWIST intensified high glucose-induced apoptosis but promoted osteogenesis differentiation of MSCs. TWIST is likely to be a new regulator for cross talk between Sirt1 and its downstream targets.

CONCLUSION

Our data demonstrates that high glucose induces MSC apoptosis and enhances osteogenesis differentiation via downregulation of AKT-Sirt1-TWIST.

Challenges to Improve Bone Healing Under Diabetic Conditions

Diabetes mellitus (DM) can affect bone metabolism and the bone microenvironment, resulting in impaired bone healing. The mechanisms include oxidative stress, inflammation, the production of advanced glycation end products (AGEs), etc. Improving bone healing in diabetic patients has important clinical significance in promoting fracture healing and improving bone integration. In this paper, we reviewed the methods of improving bone healing under diabetic conditions, including drug therapy, biochemical cues, hyperbaric oxygen, ultrasound, laser and pulsed electromagnetic fields, although most studies are in preclinical stages. Meanwhile, we also pointed out some shortcomings and challenges, hoping to provide a potential therapeutic strategy for accelerating bone healing in patients with diabetes.