Effects of Type 2 Diabetic Serum on Proliferation and Osteogenic Differentiation of Mesenchymal Stem Cells

Stem cell secretome restore the adipo-osteo differentiation imbalance in diabetic dental pulp-derived mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) from type 2 diabetes mellitus (T2DM) individuals exhibit increased adipogenesis and decreased osteogenesis. We investigated the potential of adipose tissue-derived MSCs (ADMSCs) secretome obtained from healthy individuals in restoring the tumor necrosis factor-α (TNF-α) mediated imbalance in the adipo/osteogenic differentiation in the dental pulp-derived MSCs obtained from T2DM individuals (dDPMSCs).

Methods

dDPMSCs were differentiated into adipocytes and osteocytes using a standard cocktail in the presence of (a) induction cocktail, (b) induction cocktail + TNF-α, and (c) induction cocktail+ TNF-α + ADMSCs-secretome (50%) for 15 and 21 days resp. Differentiated adipocytes and osteocytes were stained by oil red O and alizarin red and analyzed by using ImageJ software. Molecular expression of the key genes involved was analyzed by using reverse-transcription polymerase chain reaction (RT-PCR).

Results

Treatment of TNF-α augmented the adipogenesis (9571 ± 765 vs. 19,815 ± 1585 pixel, p < 0.01) and decreased the osteogenesis (15,603 ± 1248 vs. 11,894 ± 951 pixel, p < 0.05) of dDPMSCs as evidenced by the oil red O and alizarin red staining respectively. Interestingly, dDPMSCs differentiated along with TNF-α and 50% ADMSCs secretome exhibited enhanced osteogenesis (11,894 ± 951 vs. 41,808 ± 3344 pixel, p < 0.01) and decreased adipogenesis (19,815 ± 1585 vs. 4480 ± 358 pixel, p < 0.01). Additionally, dDPMSCs differentiated along with ADMSCs secretome exhibited decreased expression of PPARg (p < 0.01), C/EBPa (p < 0.05), and FAS (p < 0.01) whereas mRNA expression of Runx2 (p < 0.05), Osterix (p < 0.01), and OCN (p < 0.05) was upregulated as revealed by the RT-PCR analysis.

Conclusion

ADMSCs secretome from healthy individuals restore the TNF-α influenced differentiation fate of dDPMSCs and therefore can be explored for T2DM clinical management in the future.

Extracellular Vesicles Derived from H2O2-Stimulated Adipose-Derived Stem Cells Alleviate Senescence in Diabetic Bone Marrow Mesenchymal Stem Cells and Restore Their Osteogenic Capacity

Introduction

Autologous stem cell transplantation has emerged as a promising strategy for bone repair. However, the osteogenic potential of mesenchymal stem cells derived from diabetic patients is compromised, possibly due to hyperglycemia-induced senescence. The objective of this study was to assess the preconditioning effects of extracellular vesicles derived from H2O2-stimulated adipose-derived stem cells (ADSCs) and non-modified ADSCs on the osteogenic potential of diabetic bone marrow mesenchymal stem cells (BMSCs).

Methods

Sprague-Dawley (SD) rats were experimentally induced into a diabetic state through a high-fat diet followed by an injection of streptozotocin, and diabetic BMSCs were collected from the bone marrow of these rats. Extracellular vesicles (EVs) were isolated from the conditioned media of ADSCs, with or without hydrogen peroxide (H2O2) preconditioning, using density gradient centrifugation. The effects of H2O2 preconditioning on the morphology, marker expression, and particle size of the EVs were analyzed. Furthermore, the impact of EV-pretreatment on the viability, survivability, migration ability, osteogenesis, cellular senescence, and oxidative stress of diabetic BMSCs was examined. Moreover, the expression of the Nrf2/HO-1 pathway was also assessed to explore the underlying mechanism. Additionally, we transplanted EV-pretreated BMSCs into calvarial defects in diabetic rats to assess their in vivo bone formation and anti-senescence capabilities.

Results

Our study demonstrated that pretreatment with EVs from ADSCs significantly improved the viability, senescence, and osteogenic differentiation potential of diabetic BMSCs. Moreover, in-vitro experiments revealed that diabetic BMSCs treated with H2O2-activated EVs exhibited increased viability, reduced senescence, and enhanced osteogenic differentiation compared to those treated with non-modified EVs. Furthermore, when transplanted into rat bone defects, diabetic BMSCs treated with H2O2-activated EVs showed improved bone regeneration potential and enhanced anti-senescence function t compared to those treated with non-modified EVs. Both H2O2-activated EVs and non-modified EVs upregulated the expression of the Nrf2/HO-1 pathway in diabetic BMSCs, however, the promoting effect of H2O2-activated EVs was more pronounced than that of non-modified EVs.

Conclusion

Extracellular vesicles derived from H2O2-preconditioned ADSCs mitigated senescence in diabetic BMSCs and enhanced their bone regenerative functions via the activation of the Nrf2/HO-1 pathway.

Type 2 diabetic mellitus related osteoporosis: focusing on ferroptosis

With the aging global population, type 2 diabetes mellitus (T2DM) and osteoporosis(OP) are becoming increasingly prevalent. Diabetic osteoporosis (DOP) is a metabolic bone disorder characterized by abnormal bone tissue structure and reduced bone strength in patients with diabetes. Studies have revealed a close association among diabetes, increased fracture risk, and disturbances in iron metabolism. This review explores the concept of ferroptosis, a non-apoptotic cell death process dependent on intracellular iron, focusing on its role in DOP. Iron-dependent lipid peroxidation, particularly impacting pancreatic β-cells, osteoblasts (OBs) and osteoclasts (OCs), contributes to DOP. The intricate interplay between iron dysregulation, which comprises deficiency and overload, and DOP has been discussed, emphasizing how excessive iron accumulation triggers ferroptosis in DOP. This concise overview highlights the need to understand the complex relationship between T2DM and OP, particularly ferroptosis. This review aimed to elucidate the pathogenesis of ferroptosis in DOP and provide a prospective for future research targeting interventions in the field of ferroptosis.

The treatment efficacy of bone tissue engineering strategy for repairing segmental bone defects under diabetic condition

Background

Diabetes mellitus is a systematic disease which exert detrimental effect on bone tissue. The repair and reconstruction of bone defects in diabetic patients still remain a major clinical challenge. This study aims to investigate the potential of bone tissue engineering approach to improve bone regeneration under diabetic condition.

Methods

In the present study, decalcified bone matrix (DBM) scaffolds were seeded with allogenic fetal bone marrow-derived mesenchymal stem cells (BMSCs) and cultured in osteogenic induction medium to fabricate BMSC/DBM constructs. Then the BMSC/DBM constructs were implanted in both subcutaneous pouches and large femoral bone defects in diabetic (BMSC/DBM in DM group) and non-diabetic rats (BMSC/DBM in non-DM group), cell-free DBM scaffolds were implanted in diabetic rats to serve as the control group (DBM in DM group). X-ray, micro-CT and histological analyses were carried out to evaluate the bone regenerative potential of BMSC/DBM constructs under diabetic condition.

Results

In the rat subcutaneous implantation model, quantitative micro-CT analysis demonstrated that BMSC/DBM in DM group showed impaired bone regeneration activity compared with the BMSC/DBM in non-DM group (bone volume: 46 ± 4.4 mm3 vs 58.9 ± 7.15 mm3, *p < 0.05). In the rat femoral defect model, X-ray examination demonstrated that bone union was delayed in BMSC/DBM in DM group compared with BMSC/DBM in non-DM group. However, quantitative micro-CT analysis showed that after 6 months of implantation, there was no significant difference in bone volume and bone density between the BMSC/DBM in DM group (199 ± 63 mm3 and 593 ± 65 mg HA/ccm) and the BMSC/DBM in non-DM group (211 ± 39 mm3 and 608 ± 53 mg HA/ccm). Our data suggested that BMSC/DBM constructs could repair large bone defects in diabetic rats, but with delayed healing process compared with non-diabetic rats.

Conclusion

Our study suggest that biomaterial sacffolds seeded with allogenic fetal BMSCs represent a promising strategy to induce and improve bone regeneration under diabetic condition.

Characterisation and Expression of Osteogenic and Periodontal Markers of Bone Marrow Mesenchymal Stem Cells (BM-MSCs) from Diabetic Knee Joints

Type 2 diabetes mellitus (T2DM) represents a significant health problem globally and is linked to a number of complications such as cardiovascular disease, bone fragility and periodontitis. Autologous bone marrow mesenchymal stem cells (BM-MSCs) are a promising therapeutic approach for bone and periodontal regeneration; however, the effect of T2DM on the expression of osteogenic and periodontal markers in BM-MSCs is not fully established. Furthermore, the effect of the presence of comorbidities such as diabetes and osteoarthritis on BM-MSCs is also yet to be investigated. In the present study, BM-MSCs were isolated from osteoarthritic knee joints of diabetic and nondiabetic donors. Both cell groups were compared for their clonogenicity, proliferation rates, MSC enumeration and expression of surface markers. Formation of calcified deposits and expression of osteogenic and periodontal markers were assessed after 1, 2 and 3 weeks of basal and osteogenic culture. Diabetic and nondiabetic BM-MSCs showed similar clonogenic and growth potentials along with comparable numbers of MSCs. However, diabetic BM-MSCs displayed lower expression of periostin (POSTN) and cementum protein 1 (CEMP-1) at Wk3 osteogenic and Wk1 basal cultures, respectively. BM-MSCs from T2DM patients might be suitable candidates for stem cell-based therapeutics. However, further investigations into these cells' behaviours in vitro and in vivo under inflammatory environments and hyperglycaemic conditions are still required.

P53 negatively regulates the osteogenic differentiation in jaw bone marrow MSCs derived from diabetic osteoporosis

Patients with diabetic osteoporosis (DOP) often suffer from poor osseointegration of artificial implants, which is a challenge that affects implant outcomes. The osteogenic differentiation ability of human jaw bone marrow mesenchymal stem cells (JBMMSCs) is the key to implant osseointegration. Studies have shown that the microenvironment of hyperglycemia affects the osteogenic differentiation of mesenchymal stem cells (MSC), but the mechanism is still unclear. Therefore, the aim of this study was to isolate and culture JBMMSCs from surgically derived bone fragments from DOP patients and control patients to investigate the differences in their osteogenic differentiation ability and to elucidate its mechanisms. The results showed that the osteogenic ability of hJBMMSCs was significantly decreased in the DOP environment. Mechanism study showed that the expression of senescence marker gene P53 was significantly increased in DOP hJBMMSCs compared to control hJBMMSCs according to RNA-sequencing result. Further, DOP hJBMMSCs were found to display significant senescence using β-galactosidase staining, mitochondrial membrane potential and ROS assay, qRT-PCR and WB analysis. Overexpression of P53 in hJBMMSCs, knockdown of P53 in DOP hJBMMSCs, and knockdown followed by overexpression of P53 significantly affected the osteogenic differentiation ability of hJBMMSCs. These results suggest that MSC senescence is an important reason for decreasing osteogenic capacity in DOP patients. P53 is a key target in regulating hJBMMSCs aging, and knocking down P53 can effectively restore the osteogenic differentiation ability of DOP hJBMMSCs and promote osteosynthesis in DOP dental implants. It provided a new idea to elucidate the pathogenesis and treatment of diabetic bone metabolic diseases.

Effects of SIRT1 on Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells in Type 2 Diabetic Patients

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) are at high risk for osteoporosis. SIRT1 plays an important regulatory role in the occurrence and development of diabetes mellitus; however, it is still not clear whether SIRT1 is directly related to the osteogenic ability of bone marrow mesenchymal stem cells (BMSCs) in T2DM patients.

METHODS

We obtained BMSCs from patients with T2DM and healthy volunteers to determine the effect of SIRT1 expression on the osteogenic capacity of BMSCs. As a result, SIRT1 expression in BMSCs in T2DM was significantly lower compared to healthy volunteers, but the proliferative capacity of BMSCs in the T2DM group was not significantly different from that of healthy volunteers.

RESULTS

During osteogenic differentiation, the expression of SIRT1 in MSCs from T2DM patients was significantly decreased, and the osteogenic differentiation ability of MSCs from T2DM patients was significantly lower than healthy volunteers. After intervention with resveratrol, the expression of SIRT1 increased significantly, and the apoptotic rate of MSCs in T2DM patients decreased significantly. Moreover, resveratrol promoted osteoblast differentiation of MSCs.

CONCLUSION

Our study confirmed that the expression of SIRT1 is directly related to the osteogenic potential of BMSCs in patients with T2DM. Resveratrol promoted the osteogenic differentiation of BMSCs by increasing the expression of SIRT1. The increased expression of SIRT1 significantly reduced BMSC apoptosis during osteogenic differentiation, which is one of the important mechanisms by which SIRT1 regulates the osteogenic ability of BMSCs. Our data also provide strong evidence that resveratrol may be used in the treatment of osteoporosis in patients with T2DM.

MicroRNA-139-5p mediates BMSCs impairment in diabetes by targeting HOXA9/c-Fos

The properties and functions of BMSCs were altered by the diabetic microenvironment, and its mechanism was not very clear. In recent years, the regulation of the function of BMSCs by microRNA has become a research hotspot, meanwhile, HOX genes also have been focused on and involved in multiple functions of stem cells. In this study, we investigated the role of miR-139-5p in diabetes-induced BMSC impairment. Since HOXA9 may be a target gene of miR-139-5p, we speculated that miR-139-5p/HOXA9 might be involved in regulating the biological characteristics and the function of BMSCs in diabetes. We demonstrated that the miR-139-5p expression was increased in BMSCs derived from STZ-induced diabetic rats. MiR-139-5p mimics were able to inhibit cell proliferation, and migration and promoted senescence and apoptosis in vitro. MiR-139-5p induced the down-regulated expression of HOXA9 and c-Fos in BMSCs derived from normal rats. Moreover, miR-139-5p inhibitors reversed the tendency in diabetic-derived BMSCs. Further, gain-and-loss function experiments indicated that miR-139-5p regulated the functions of BMSCs by targeting HOXA9 and c-Fos. In vivo wound model experiments showed that the downregulation of miR-139-5p further promoted the epithelialization and angiogenesis of diabetic BMSC-mediated skin. In conclusion, induction of miR-139-5p upregulation mediated the impairment of BMSCs through the HOXA9/c-Fos pathway in diabetic rats. Therefore, miR-139-5p/HOXA9 might be an important therapeutic target in treating diabetic BMSCs and diabetic complications in the future.

Recovering Osteoblast Functionality on TiO2 Nanotube Surfaces Under Diabetic Conditions

Introduction

Titanium (Ti) and its alloys (eg, Ti₆Al₄V) are exceptional treatments for replacing or repairing bones and damaged surrounding tissues. Although Ti-based implants exhibit excellent osteoconductive performance under healthy conditions, the effectiveness and successful clinical achievements are negatively altered in diabetic patients. Concernedly, diabetes mellitus (DM) contributes to osteoblastic dysfunctionality, altering efficient osseointegration. This work investigates the beneficial osteogenic activity conducted by nanostructured TiO₂ under detrimental microenvironment conditions, simulated by human diabetic serum.

Methods

We evaluated the bone-forming functional properties of osteoblasts on synthesized TiO₂ nanotubes (NTs) by anodization and Ti6Al4V non-modified alloy surfaces under detrimental diabetic conditions. To simulate the detrimental environment, MC3T3E-1 preosteoblasts were cultured under human diabetic serum (DS) of two diagnosed and metabolically controlled patients. Normal human serum (HS) was used to mimic health conditions and fetal bovine serum (FBS) as the control culture environment. We characterized the matrix mineralization under the detrimental conditions on the control alloy and the NTs. Moreover, we applied immunofluorescence of osteoblasts differentiation markers on the NTs to understand the bone-expression stimulated by the biochemical medium conditions.

Results

The diabetic conditions depressed the initial osteoblast growth ability, as evidenced by altered early cell adhesion and reduced proliferation. Nonetheless, after three days, the diabetic damage was suppressed by the NTs, enhancing the osteoblast activity. Therefore, the osteogenic markers of bone formation and the differentiation of osteoblasts were reactivated by the nanoconfigured surfaces. Far more importantly, collagen secretion and bone-matrix mineralization were stimulated and conducted to levels similar to those of the control of FBS conditions, in comparison to the control alloy, which was not able to reach similar levels of bone functionality than the NTs.

Conclusion

Our study brings knowledge for the potential application of nanostructured biomaterials to work as an integrative platform under the detrimental metabolic status present in diabetic conditions.

A gene expression profile for the lower osteogenic potent of bone-derived MSCs from osteoporosis with T2DM and the potential mechanism

Background

Osteoporosis (OP) patients complicated with type II diabetes mellitus (T2DM) has a higher fracture risk than the non-diabetic patients, and mesenchymal stem cells (MSCs) from T2DM patients also show a weaker osteogenic potent. The present study aimed to provide a gene expression profile in MSCs from diabetic OP and investigated the potential mechanism.

Methods

The bone-derived MSC (BMSC) was isolated from OP patients complicated with or without T2DM (CON-BMSC, T2DM-BMSC). Osteogenic differentiation was evaluated by qPCR analysis of the expression levels of osteogenic markers, ALP activity and mineralization level. The differentially expressed genes (DEGs) in T2DM-BMSC was identified by RNA-sequence, and the biological roles of DEGs was annotated by bioinformatics analyses. The role of silencing the transcription factor (TF), Forkhead box Q1 (FOXQ1), on the osteogenic differentiation of BMSC was also investigated.

Results

T2DM-BMSC showed a significantly reduced osteogenic potent compare to the CON-BMSC. A total of 448 DEGs was screened in T2DM-BMSC, and bioinformatics analyses showed that many TFs and the target genes were enriched in various OP- and diabetes-related biological processes and pathways. FOXQ1 had the highest verified fold change (abs) among the top 8 TFs, and silence of FOXQ1 inhibited the osteogenic differentiation of CON-BMSC.

Conclusions

Our study provided a comprehensive gene expression profile of BMSC in diabetic OP, and found that downregulated FOXQ1 was responsible for the reduced osteogenic potent of T2DM-BSMC. This is of great importance for the special mechanism researches and the treatment of diabetic OP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03291-2.

Impaired bone fracture healing in type 2 diabetes is caused by defective functions of skeletal progenitor cells

The mechanisms of obesity and type 2 diabetes (T2D)-associated impaired fracture healing are poorly studied. In a murine model of T2D reflecting both hyperinsulinemia induced by high fat diet (HFD) and insulinopenia induced by treatment with streptozotocin (STZ), we examined bone healing in a tibia cortical bone defect. A delayed bone healing was observed during hyperinsulinemia as newly formed bone was reduced by – 28.4±7.7% and was associated with accumulation of marrow adipocytes at the defect site +124.06±38.71%, and increased density of SCA1+ (+74.99± 29.19%) but not Runx2 +osteoprogenitor cells. We also observed increased in reactive oxygen species production (+101.82± 33.05%), senescence gene signature (≈106.66± 34.03%) and LAMIN B1 - senescent cell density (+225.18± 43.15%), suggesting accelerated senescence phenotype. During insulinopenia, a more pronounced delayed bone healing was observed with decreased newly formed bone to -34.9± 6.2% which was inversely correlated with glucose levels (R 2=0.48, p&lt;0.004) and callus adipose tissue area (R 2=0.3711, p&lt;0.01). Finally, to investigate the relevance to human physiology, we observed that sera from obese and T2D subjects had disease state-specific inhibitory effects on osteoblast related gene signatures in human bone marrow stromal cells which resulted in inhibition of osteoblast and enhanced adipocyte differentiation. Our data demonstrate that T2D exerts negative effects on bone healing through inhibition of osteoblast differentiation of skeletal stem cells and induction of accelerated bone senescence and that the hyperglycaemia per se and not just insulin levels is detrimental for bone healing.

Fracture risk assessment in diabetes mellitus

Growing evidence suggests that diabetes mellitus is associated with an increased risk of fracture. Bone intrinsic factors (such as accumulation of glycation end products, low bone turnover, and bone microstructural changes) and extrinsic factors (such as hypoglycemia caused by treatment, diabetes peripheral neuropathy, muscle weakness, visual impairment, and some hypoglycemic agents affecting bone metabolism) probably contribute to damage of bone strength and the increased risk of fragility fracture. Traditionally, bone mineral density (BMD) measured by dual x-ray absorptiometry (DXA) is considered to be the gold standard for assessing osteoporosis. However, it cannot fully capture the changes in bone strength and often underestimates the risk of fracture in diabetes. The fracture risk assessment tool is easy to operate, giving it a certain edge in assessing fracture risk in diabetes. However, some parameters need to be regulated or replaced to improve the sensitivity of the tool. Trabecular bone score, a noninvasive tool, indirectly evaluates bone microstructure by analyzing the texture sparsity of trabecular bone, which is based on the pixel gray level of DXA. Trabecular bone score combined with BMD can effectively improve the prediction ability of fracture risk. Quantitative computed tomography is another noninvasive examination of bone microstructure. High-resolution peripheral quantitative computed tomography can measure volume bone mineral density. Quantitative computed tomography combined with microstructure finite element analysis can evaluate the mechanical properties of bones. Considering the invasive nature, the use of microindentation and histomorphometry is limited in clinical settings. Some studies found that the changes in bone turnover markers in diabetes might be associated with fracture risk, but further studies are needed to confirm this. This review focused on summarizing the current development of these assessment tools in diabetes so as to provide references for clinical practice. Moreover, these tools can reduce the occurrence of fragility fractures in diabetes through early detection and intervention.

The Effect of Diabetes Mellitus on IGF Axis and Stem Cell Mediated Regeneration of the Periodontium

Periodontitis and diabetes mellitus (DM) are two of the most common and challenging health problems worldwide and they affect each other mutually and adversely. Current periodontal therapies have unpredictable outcome in diabetic patients. Periodontal tissue engineering is a challenging but promising approach that aims at restoring periodontal tissues using one or all of the following: stem cells, signalling molecules and scaffolds. Mesenchymal stem cells (MSCs) and insulin-like growth factor (IGF) represent ideal examples of stem cells and signalling molecules. This review outlines the most recent updates in characterizing MSCs isolated from diabetics to fully understand why diabetics are more prone to periodontitis that theoretically reflect the impaired regenerative capabilities of their native stem cells. This characterisation is of utmost importance to enhance autologous stem cells based tissue regeneration in diabetic patients using both MSCs and members of IGF axis.

The Fate Status of Stem Cells in Diabetes and its Role in the Occurrence of Diabetic Complications

Diabetes mellitus (DM) is becoming a growing risk factor for public health worldwide. It is a very common disease and is widely known for its susceptibility to multiple complications which do great harm to the life and health of patients, some even lead to death. To date, there are many mechanisms for the complications of diabetes, including the generation of reactive oxygen species (ROS) and the abnormal changes of gas transmitters, which ultimately lead to injuries of cells, tissues and organs. Normally, even if injured, the body can quickly repair and maintain its homeostasis. This is closely associated with the repair and regeneration ability of stem cells. However, many studies have demonstrated that stem cells happen to be damaged under DM, which may be a nonnegligible factor in the occurrence and progression of diabetic complications. Therefore, this review summarizes how diabetes causes the corresponding complications by affecting stem cells from two aspects: stem cells dysfunctions and stem cells quantity alteration. In addition, since mesenchymal stem cells (MSCs), especially bone marrow mesenchymal stem cells (BMMSCs), have the advantages of strong differentiation ability, large quantity and wide application, we mainly focus on the impact of diabetes on them. The review also puts forward the basis of using exogenous stem cells to treat diabetic complications. It is hoped that through this review, researchers can have a clearer understanding of the roles of stem cells in diabetic complications, thus promoting the process of using stem cells to treat diabetic complications.

microRNA-491-5p regulates osteogenic differentiation of bone marrow stem cells in type 2 diabetes

OBJECTIVES

Osseointegration of oral implants has a low success rate in patients with type 2 diabetes. This is because of the inhibition of osteogenic differentiation in the jawbone marrow mesenchymal stem cells, in which the expression of microRNA(miR)-491-5p is significantly downregulated, as ascertained through gene chip screening. However, the underlying mechanisms are unclear. Here, we aimed to clarify the mechanisms involved in the influence of miR-491-5p on osteogenic differentiation.

SUBJECTS AND METHODS

Jawbone marrow mesenchymal stem cells were isolated from jawbones of patients with type 2 diabetes and subjected to bioinformatics and functional analyses. Osteogenesis experiments were conducted using the isolated cells and an in vivo model.

RESULTS

Knockdown and overexpression experiments revealed the positive effects of miR-491-5p expression on osteogenic differentiation in vivo and in vitro. Additionally, a dual-luciferase assay revealed that miR-491-5p targeted the SMAD/RUNX2 pathway by inhibiting the expression of epidermal growth factor receptor.

CONCLUSIONS

miR-491-5p is vital in osteogenic differentiation of jawbone mesenchymal stem cells; its downregulation in type 2 diabetes could be a major cause of decreased osteogenic differentiation. Regulation of miR-491-5p expression could improve osteogenic differentiation of jawbone mesenchymal stem cells in patients with type 2 diabetes.

Pre-conditioning of Mesenchymal Stem Cells with Piper longum L. augments osteogenic differentiation

ETHNOPHARMACOLOGICAL RELEVANCE

The Indian Traditional Medicine, Ayurveda prescribes Piper longum L. popularly known as Long Pepper (Pippali) for the treatment of inflammatory and degenerative diseases. Therapeutic benefits of Piper longum L. are mainly attributed to the anti-inflammatory and arthritic potential.

AIM OF THE STUDY

This study was aimed to explore the activity of Piper longum L. fruit extract on proliferation and osteogenic differentiation of human Wharton's Jelly Mesenchymal Stem Cells (WJMSCs) to find out it's possible role as anti-osteoporotic agent.

MATERIALS AND METHODS

Proliferation of WJMSCs treated with Piper longum L. fruit extract was assessed by MTT assay and Cell Cycle Analysis. Effect of Piper longum L. preconditioning on osteogenic differentiation was performed. Ca2+ accumulation and matrix mineralization (Von Kossa and Alizarin Red Staining), alkaline phosphatase (ALP) activity and gene expression of key mRNA (RT PCR) was analyzed.

RESULTS

Significant increase in the proliferation of WJMSCs was observed upon treatment of Piper longum L. at 5 μg/mL (P < 0.001) which can be attributed to the significant decrease in apoptotic cells (P < 0.05) as evidenced by cell cycle analysis. Preconditioning of Piper longum L. (10-100 μg/mL) enhanced Ca2+ accumulation and matrix mineralization as observed by Von Kossa and Alizarin Red staining where ALP activity was elevated 3.6 folds as compared to untreated WJMSCs (P < 0.001). RT-PCR analysis exhibited up regulation of Runx2, Osterix, ALP and OPN mRNAs.

CONCLUSIONS

We demonstrate for the first time that Piper longum L. fruit extract enhanced osteogenic differentiation of WJMSCs. This finding can be clinically translated into development of an anti-osteoporotic agent.

Fundamental changes in endogenous bone marrow mesenchymal stromal cells during Type I Diabetes is a pre-neuropathy event

Deficiency of angiogenic and neurotrophic factors under long term diabetes is known to lead to Schwann cell degeneration, clinically manifested as Diabetic Neuropathy (DN). While the transplantation of exogenous allogenic Mesenchymal Stromal Cells (MSCs) has shown amelioration of DN through paracrine action, it is not known what functional changes occur in endogenous bone-marrow MSCs under chronic diabetes in terms of homing, migration and/or paracrine signalling with reference to the end-point clinical manifestation of Diabetic Neuropathy. We thus aimed at determining the changes in BM-MSCs under Type 1 Diabetes with respect to survival, self-renewal, oxidative status, paracrine activity, intracellular Ca²⁺ response and migration in response to pathological cytokine/chemokine, in reference to the time-point of decline in Nerve Conduction Velocity (NCV) in a rat model. Within one week of diabetes induction, BM-MSCs underwent apoptosis, and compromised their self-renewal capacity, antioxidant defence mechanism and migration toward cytokine/chemokine; whereas epineurial blood vessel thickening and demyelination resulting in NCV decline were observed only after three weeks. By two- and three-weeks post diabetes induction, BM-MSC apoptosis reduced and proliferative ability was restored; however, their self-renewal, migration and intracellular Ca²⁺ response toward pathological cytokine/chemokine remained impaired. These results indicate that T1D induced intrinsic functional impairments in endogenous BM-MSCs occur before neuropathy onset. This timeline of functional alterations in BM-MSCs also suggest that treatment strategies that target the bone marrow niche early on may help to modulate BM-MSC functional impairments and thus slow down the progression of neuropathy.

Type 2 diabetes mellitus duration and obesity alter the efficacy of autologously transplanted bone marrow-derived mesenchymal stem/stromal cells

Human bone marrow-derived mesenchymal stem/stromal cells (BM-MSCs) represent promising stem cell therapy for the treatment of type 2 diabetes mellitus (T2DM), but the results of autologous BM-MSC administration in T2DM patients are contradictory. The purpose of this study was to test the hypothesis that autologous BM-MSC administration in T2DM patient is safe and that the efficacy of the treatment is dependant on the quality of the autologous BM-MSC population and administration routes. T2DM patients were enrolled, randomly assigned (1:1) by a computer-based system into the intravenous and dorsal pancreatic arterial groups. The safety was assessed in all the treated patients, and the efficacy was evaluated based on the absolute changes in the hemoglobin A1c, fasting blood glucose, and C-peptide levels throughout the 12-month follow-up. Our data indicated that autologous BM-MSC administration was well tolerated in 30 T2DM patients. Short-term therapeutic effects were observed in patients with T2DM duration of <10 years and a body mass index <23, which is in line with the phenotypic analysis of the autologous BM-MSC population. T2DM duration directly altered the proliferation rate of BM-MSCs, abrogated the glycolysis and mitochondria respiration of BM-MSCs, and induced the accumulation of mitochondria DNA mutation. Our data suggest that autologous administration of BM-MSCs in the treatment of T2DM should be performed in patients with T2DM duration <10 years and no obesity. Prior to further confirming the effects of T2DM on BM-MSC biology, future work with a larger cohort focusing on patients with different T2DM history is needed to understand the mechanism underlying our observation.

Uncarboxylated osteocalcin alleviates the inhibitory effect of high glucose on osteogenic differentiation of mouse bone marrow-derived mesenchymal stem cells by regulating TP63

BACKGROUND

Progressive population aging has contributed to the increased global prevalence of diabetes and osteoporosis. Inhibition of osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) by hyperglycemia is a potential pathogenetic mechanism of osteoporosis in diabetic patients. Uncarboxylated osteocalcin (GluOC), a protein secreted by mature osteoblasts, regulates bone development as well as glucose and lipid metabolism. In our previous studies, GluOC was shown to promote osteoblastic differentiation of BMSCs; however, the underlying mechanisms are not well characterized. Tumor protein 63 (TP63), as a  transcription factor, is closely related to bone development and glucose metabolism.

RESULTS

In this study, we verified that high glucose suppressed osteogenesis and upregulated adipogenesis in BMSCs, while GluOC alleviated this phenomenon. In addition, high glucose enhanced TP63 expression while GluOC diminished it. Knock-down of TP63 by siRNA transfection restored the inhibitory effect of high glucose on osteogenic differentiation. Furthermore, we detected the downstream signaling pathway PTEN/Akt/GSK3β. We found that diminishing TP63 decreased PTEN expression and promoted the phosphorylation of Akt and GSK3β. We then applied the activator and inhibitor of Akt, and concluded that PTEN/Akt/GSK3β participated in regulating the differentiation of BMSCs.

CONCLUSIONS

Our results indicate that GluOC reduces the inhibitory effect of high glucose on osteoblast differentiation by regulating the TP63/PTEN/Akt/GSK3β pathway. TP63 is a potential novel target for the prevention and treatment of diabetic osteoporosis.

Impact of Type 2 Diabetes Mellitus and Antidiabetic Medications on Bone Metabolism

PURPOSE OF REVIEW

This review focuses on the complex interactions between hyperglycemia and bone fragility and the effects of antidiabetic medications on bone metabolism.

RECENT FINDINGS

Type 2 diabetes (T2D) is associated with increased risk of bone fracture even in those with increased or normal bone mineral density (BMD). The pathophysiology of diabetic bone disease is not completely understood, but it is thought to be multifactorial and associated with complex cross talk among factors such as AGEs, IGF-1, enteric hormones, and pro-inflammatory cytokines. Treatment for T2D may have an impact on bone metabolism. Diabetic bone disease should be considered a serious complication of long-standing T2D.

Mesenchymal Stem Cell Therapy for Diabetic Kidney Disease: A Review of the Studies Using Syngeneic, Autologous, Allogeneic, and Xenogeneic Cells

Diabetic kidney disease (DKD) is a microvascular complication of diabetes mellitus (DM) and comprises multifactorial pathophysiologic mechanisms. Despite current treatment, around 30-40% of individuals with type 1 and type 2 DM (DM1 and DM2) have progressive DKD, which is the most common cause of end-stage chronic kidney disease worldwide. Mesenchymal stem cell- (MSC-) based therapy has important biological and therapeutic implications for curtailing DKD progression. As a chronic disease, DM may impair MSC microenvironment, but there is compelling evidence that MSC derived from DM1 individuals maintain their cardinal properties, such as potency, secretion of trophic factors, and modulation of immune cells, so that both autologous and allogeneic MSCs are safe and effective. Conversely, MSCs derived from DM2 individuals are usually dysfunctional, exhibiting higher rates of senescence and apoptosis and a decrease in clonogenicity, proliferation, and angiogenesis potential. Therefore, more studies in humans are needed to reach a conclusion if autologous MSCs from DM2 individuals are effective for treatment of DM-related complications. Importantly, the bench to bedside pathway has been constructed in the last decade for assessing the therapeutic potential of MSCs in the DM setting. Laboratory research set the basis for establishing further translation research including preclinical development and proof of concept in model systems. Phase I clinical trials have evaluated the safety profile of MSC-based therapy in humans, and phase II clinical trials (proof of concept in trial participants) still need to answer important questions for treating DKD, yet metabolic control has already been documented. Therefore, randomized and controlled trials considering the source, optimal cell number, and route of delivery in DM patients are further required to advance MSC-based therapy. Future directions include strategies to reduce MSC heterogeneity, standardized protocols for isolation and expansion of those cells, and the development of well-designed large-scale trials to show significant efficacy during a long follow-up, mainly in individuals with DKD.

The impact of ageing on lipid-mediated regulation of adult stem cell behavior and tissue homeostasis

Adult stem cells sustain tissue homeostasis throughout life and provide an important reservoir of cells capable of tissue repair in response to stress and tissue damage. Age-related changes to stem cells and/or the specialized niches that house them have been shown to negatively impact stem cell maintenance and activity. In addition, metabolic inputs have surfaced as another crucial layer in the control of stem cell behavior (Chandel et al., 2016; Folmes and Terzic, 2016; Ito and Suda, 2014; Mana et al., 2017; Shyh-Chang and Ng, 2017). Here, we will present a brief review of how lipid metabolism influences adult stem cell behavior under homeostatic conditions and speculate on how changes in lipid metabolism may impact stem cell ageing. This review considers the future of lipid metabolism research in stem cells, with the long-term goal of identifying mechanisms that could be targeted to counter or slow the age-related decline in stem cell function.

NIPA2 regulates osteoblast function by modulating mitophagy in type 2 diabetes osteoporosis

The highly selective magnesium transporter non-imprinted in Prader-Willi/Angelman syndrome region protein 2 (NIPA2) has recently been associated with the development and progression of type 2 diabetes osteoporosis, but the mechanisms involved are still poorly understood. Because mitophagy is involved in the pathology of type 2 diabetes osteoporosis, the present study aimed to explore the relationship among NIPA2, mitophagy and osteoblast osteogenic capacity. NIPA2 expression was reduced in C57BKS background db/db mice and in vitro models of type 2 diabetes osteoporosis, and the activation of mitophagy in primary culture osteoblast-derived from db/db mice and in high glucose-treated human fetal osteoblastic cells (hFOB1.19) was observed. Knockdown, overexpression of NIPA2 and pharmacological inhibition of peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) showed that NIPA2 increased osteoblast function, which was likely regulated by PTEN induced kinase 1 (PINK1)/E3 ubiquitin ligase PARK2 (Parkin)-mediated mitophagy via the PGC-1α/forkhead box O3a(FoxO3a)/mitochondrial membrane potential (MMP) pathway. Furthermore, the negative effect of mitophagy on osteoblast function was confirmed by pharmacological regulation of mitophagy and knockdown of Parkin. Taken together, these results suggest that NIPA2 positively regulates the osteogenic capacity of osteoblasts via the mitophagy pathway in type 2 diabetes.

Mesenchymal Stem Cells in Homeostasis and Systemic Diseases: Hypothesis, Evidences, and Therapeutic Opportunities

Mesenchymal stem cells (MSCs) are present in all organs and tissues, playing a well-known function in tissue regeneration. However, there is also evidence indicating a broader role of MSCs in tissue homeostasis. In vivo studies have shown MSC paracrine mechanisms displaying proliferative, immunoregulatory, anti-oxidative, or angiogenic activity. In addition, recent studies also demonstrate that depletion and/or dysfunction of MSCs are associated with several systemic diseases, such as lupus, diabetes, psoriasis, and rheumatoid arthritis, as well as with aging and frailty syndrome. In this review, we hypothesize about the role of MSCs as keepers of tissue homeostasis as well as modulators in a variety of inflammatory and degenerative systemic diseases. This scenario opens the possibility for the use of secretome-derived products from MSCs as new therapeutic agents in order to restore tissue homeostasis, instead of the classical paradigm "one disease, one drug".

Cell Based Therapy for Type 1 Diabetes: Should We Take Hyperglycemia Into Account?

Diabetes mellitus is characterized by long standing hyperglycemia leading to numerous life-threatening complications. For type 1 diabetes mellitus, resulting from selective destruction of insulin producing cells by exaggerated immune reaction, the only effective therapy remains exogenous insulin administration. Despite accurate compliance to treatment of certain patients, transient episodes of hyperglycemia cannot be completely eliminated by this symptomatic treatment. Novel immunotherapeutic approaches based on tolerogenic dendritic cells, T regulatory cells and mesenchymal stem cells (MSCs) have been tested in clinical trials, endeavoring to directly modulate the autoimmune destruction process in pancreas. However, hyperglycemia itself affects the immune system and the final efficacy of cell-based immunotherapies could be affected by the different glycemic control of enrolled patients. The present review explores the impact of hyperglycemia on immune cells while providing greater insight into the molecular mechanisms of high glucose action and subsequent metabolic reprogramming of different immune cells. Furthermore, over-production of mitochondrial reactive oxygen species, formation of advanced glycation end products as a consequence of hyperglycemia and their downstream signalization in immune cells are also discussed. Since hyperglycemia in patients with type 1 diabetes mellitus might have an impact on immune-interventional treatment, the maintenance of a tight glucose control seems to be beneficial in patients considered for cell-based therapy.

Mesenchymal stem cell dysfunction in diabetes

Diabetes mellitus (DM) is a chronic disease that results in a variety of systemic complications. Recently, stem cell-based therapies have been proposed as potential modalities to manage DM related complications. Mesenchymal stem cell (MSC) based therapies are often considered as an ideal stem cell-based treatment for DM management due to their immunosuppressive characteristics, anti-inflammatory properties and differentiation potential. While MSCs show tremendous promise, the underlying functional deficits of MSCs in DM patients is not well understood. Using the MEDLINE database to define these functional deficits, our search yielded 1826 articles of which 33 met our inclusion criteria. This allowed us to review the topic and illuminate four major molecular categories by which MSCs are compromised in both Type 1 DM and Type II DM models which include: (1) changes in angiogenesis/vasculogenesis, (2) altered pro-inflammatory cytokine secretion, (3) increased oxidative stress markers and (4) impaired cellular differentiation and decreased proliferation. Knowledge of the deficits in MSC function will allow us to more clearly assess the efficacy of potential biologic therapies for reversing these dysfunctions when treating the complications of diabetic disease.

Skeletal Fragility in Type 2 Diabetes Mellitus

Type 2 diabetes (T2D) is associated with an increased risk of fracture, which has been reported in several epidemiological studies. However, bone mineral density in T2D is increased and underestimates the fracture risk. Common risk factors for fracture do not fully explain the increased fracture risk observed in patients with T2D. We propose that the pathogenesis of increased fracture risk in T2D is due to low bone turnover caused by osteocyte dysfunction resulting in bone microcracks and fractures. Increased levels of sclerostin may mediate the low bone turnover and may be a novel marker of increased fracture risk, although further research is needed. An impaired incretin response in T2D may also affect bone turnover. Accumulation of advanced glycosylation endproducts may also impair bone strength. Concerning antidiabetic medication, the glitazones are detrimental to bone health and associated with increased fracture risk, and the sulphonylureas may increase fracture risk by causing hypoglycemia. So far, the results on the effect of other antidiabetics are ambiguous. No specific guideline for the management of bone disease in T2D is available and current evidence on the effects of antiosteoporotic medication in T2D is sparse. The aim of this review is to collate current evidence of the pathogenesis, detection and treatment of diabetic bone disease.