A diabetic milieu promotes OCT4 and NANOG production in human visceral-derived adipose stem cells

GKT137831 in combination with adipose-derived stem cells alleviates high glucose-induced inflammaging and improves diabetic wound healing

Adipose-derived stem cells (ADSCs) have been proven to promote healing in diabetic wounds, which are one of the most serious chronic refractory wounds. However, reactive oxygen species (ROS) induced by high glucose (HG) lead to oxidative stress and aging in ADSCs, which limits the therapeutic effect of ADSCs. In this study, we investigated the role of GKT137831, a NOX1/4 inhibitor that can reduce ROS production, in protecting ADSCs from hyperglycemia and in diabetic wound healing. In vitro, ROS levels and NOX4 expression were increased after HG treatment of ADSCs, while the oxidative stress marker malondialdehyde was increased; mitochondrial membrane potential was decreased; inflammatory aging-related indicators such as p16, p21, matrix metalloproteinase-1 (MMP1), MMP3, interleukin-6, and β-galactosidase were increased; and migration was weakened. In vivo, we constructed a diabetic mouse wound model and found that the combination of ADSCs and GKT137831 synergistically promoted the 21-day wound healing rate, increased the expression of collagen and hydroxyproline, increased the number of blood vessels and the expression of CD31, and reduced the expression of interleukin-6, MMP1, MMP3, and p21. These results suggest that GKT137831 could protect ADSCs from oxidative stress and aging induced by HG and enhance the therapeutic effect of ADSCs on diabetic wounds.

Regulation Mechanisms and Maintenance Strategies of Stemness in Mesenchymal Stem Cells

Stemness pertains to the intrinsic ability of mesenchymal stem cells (MSCs) to undergo self-renewal and differentiate into multiple lineages, while simultaneously impeding their differentiation and preserving crucial differentiating genes in a state of quiescence and equilibrium. Owing to their favorable attributes, including uncomplicated isolation protocols, ethical compliance, and ease of procurement, MSCs have become a focal point of inquiry in the domains of regenerative medicine and tissue engineering. As age increases or ex vivo cultivation is prolonged, the functionality of MSCs decreases and their stemness gradually diminishes, thereby limiting their potential therapeutic applications. Despite the existence of several uncertainties surrounding the comprehension of MSC stemness, considerable advancements have been achieved in the clarification of the potential mechanisms that lead to stemness loss, as well as the associated strategies for stemness maintenance. This comprehensive review provides a systematic overview of the factors influencing the preservation of MSC stemness, the molecular mechanisms governing it, the strategies for its maintenance, and the therapeutic potential associated with stemness. Finally, we underscore the obstacles and prospective avenues in present investigations, providing innovative perspectives and opportunities for the preservation and therapeutic utilization of MSC stemness.

Low-glucose culture environment can enhance the wound healing capability of diabetic adipose-derived stem cells

BACKGROUND

Application of autologous adipose-derived stem cells (ASC) for diabetic chronic wounds has become an emerging treatment option. However, ASCs from diabetic individuals showed impaired cell function and suboptimal wound healing effects. We proposed that adopting a low-glucose level in the culture medium for diabetic ASCs may restore their pro-healing capabilities.

METHODS

ASCs from diabetic humans and mice were retrieved and cultured in high-glucose (HG, 4.5 g/L) or low-glucose (LG, 1.0 g/L) conditions. Cell characteristics and functions were investigated in vitro. Moreover, we applied diabetic murine ASCs cultured in HG or LG condition to a wound healing model in diabetic mice to compare their healing capabilities in vivo.

RESULTS

Human ASCs exhibited decreased cell proliferation and migration with enhanced senescence when cultured in HG condition in vitro. Similar findings were noted in ASCs derived from diabetic mice. The inferior cellular functions could be partially recovered when they were cultured in LG condition. In the animal study, wounds healed faster when treated with HG- or LG-cultured diabetic ASCs relative to the control group. Moreover, higher collagen density, more angiogenesis and cellular retention of applied ASCs were found in wound tissues treated with diabetic ASCs cultured in LG condition.

CONCLUSIONS

In line with the literature, our study showed that a diabetic milieu exerts an adverse effect on ASCs. Adopting LG culture condition is a simple and effective approach to enhance the wound healing capabilities of diabetic ASCs, which is valuable for the clinical application of autologous ASCs from diabetic patients.

Visceral mesenchymal stem cells from type 2 diabetes donors activate triglycerides synthesis in healthy adipocytes via metabolites exchange and cytokines secretion

BACKGROUND

In recent years, there has been an increase in the prevalence of obesity and type 2 diabetes mellitus (T2DM). Development of visceral instead of subcutaneous adipose tissue is pathogenic and increases the risk of metabolic abnormalities. We hypothesize that visceral adipocytes and stromal cells are able to deteriorate other fat depots metabolism via secretory mechanisms.

METHODS

We study the regulatory role of visceral adipose-derived stem cells (vADSC) from donors with obesity and T2DM or normal glucose tolerance (NGT) on healthy subcutaneous ADSC (sADSC) in the Transwell system. Lipid droplets formation during adipogenesis was assessed by confocal microscopy. Cell metabolism was evaluated by 14C-glucose incorporation analysis and western blotting. vADSC secretome was assessed by Milliplex assay.

RESULTS

We showed that both NGT and T2DM vADSC had mesenchymal phenotype, but expression of CD29 was enhanced, whereas expressions of CD90, CD140b and IGF1R were suppressed in both NGT and T2DM vADSC. Co-differentiation with T2DM vADSC increased lipid droplet size and stimulated accumulation of fatty acids in adipocytes from healthy sADSC. In mature adipocytes T2DM vADSC stimulated triglyceride formation, whereas NGT vADSC activated oxidative metabolism. Secretome of NGT vADSC was pro-inflammatory and pro-angiogenic in comparison with T2DM vADSC.

CONCLUSIONS

The present study has demonstrated the critical role of secretory interactions between visceral and subcutaneous fat depots both in the level of progenitor and mature cells. Mechanisms of these interactions are related to direct exchange of metabolites and cytokines secretion.

Fatty acids of type 2 diabetic serum decrease the stemness properties of human adipose-derived mesenchymal stem cells

In type 2 diabetes, dyslipidemia and increased serum free fatty acids (FFAs) exacerbate the development of the disease through a negative effect on insulin secretion. Adipose-derived mesenchymal stem cells (AdMSCs) play a key role in regenerative medicine, and these cells can potentially be applied as novel therapeutic resources in the treatment of diabetes. In this study, AdMSCs were treated with diabetic or nondiabetic serum FFAs isolated from women of menopausal age. Serum FFAs were analyzed using gas-liquid chromatography. The expression level of the stemness markers CD49e and CD90 and the Wnt signaling target genes Axin-2 and c-Myc were evaluated using real-time PCR. The proliferation rate and colony formation were also assessed using a BrdU assay and crystal violet staining, respectively. The level of glutathione was assessed using cell fluorescence staining. Compared to nondiabetic serum, diabetic serum contained a higher percentage of oleate (1.5-fold, p < 0.01). In comparison with nondiabetic FFAs, diabetic FFAs demonstrated decreasing effects on the expression of CD90 (-51%, p < 0.001) and c-Myc (-48%, p < 0.05), and proliferation rate (-35%, p < 0.001), colony formation capacity (-50%, p < 0.01), and GSH levels (-62%, p < 0.05). The negative effect of the FFAs of diabetic serum on the stemness characteristics may impair the regenerative capabilities of AdMSCs.

What can we learn from β-cell failure biomarker application in diabetes in childhood? A systematic review

BACKGROUND

The prevalence of diabetes as a catastrophic disease in childhood is growing in the world. The search for novel biomarkers of β-cell failure has been an elusive task because it requires several clinical and biochemical measurements in order to integrate the risk of metabolic syndrome.

AIM

To determine which biomarkers are currently used to identify β-cell failure among children and adolescents with high risk factors for diabetes mellitus.

METHODS

This systematic review was carried out using a modified version of the PICO protocol (Participants/Intervention/Comparison/Outcome). Once our research question was established, terms were individually researched on three different databases (PubMed, BIREME and Web of Science). The total articles obtained underwent a selection process from which the 78 most relevant articles were retrieved to undergo further analysis. They were assessed individually according to quality criteria.

RESULTS

First, we made the classification of the β-cell-failure biomarkers by the target tissue and the evolution of the disease, separating the biomarkers in relation to the types of diabetes. Second, we demonstrated that most biomarkers currently used as early signs of β-cell failure are those that concern local or systemic inflammation processes and oxidative stress as well as those related to endothelial dysfunction processes. Third, we explored the novelties of diabetes as a protein conformational disease and the novel biomarker called real human islet amyloid polypeptide amyloid oligomers. Finally, we ended with a discussion about the best practice of validation and individual control of using different types of biomarkers in type 1 and type 2 diabetes in order to assess the role they play in the progress of diabetes in childhood.

CONCLUSION

This review makes widely evident that most biomarkers currently used as early signs of β-cell failure are those that concern local or systemic inflammation processes and oxidative stress as well as those related to endothelial dysfunction processes. Landing in the clinical practice we propose that real human islet amyloid polypeptide amyloid oligomers is good for identifying patients with β-cell damage and potentially could substitute many biomarkers.

Impact of Diabetes Mellitus on the Potential of Autologous Stem Cells and Stem Cell-Derived Microvesicles to Repair the Ischemic Heart

Ischemic heart disease remains the leading cause of morbidity and mortality worldwide. Despite the advances in medical management and catheter-based therapy, mortality remains high, as does the risk of developing heart failure. Regenerative therapies have been widely used as an alternative option to repair the damaged heart mainly because of their paracrine-related beneficial effects. Although cell-based therapy has been demonstrated as feasible and safe, randomized controlled trials and meta-analyses show little consistent benefit from treatments with adult-derived stem cells. Mounting evidence from our group and others supports that cardiovascular risk factors and comorbidities impair stem cell potential thus hampering their autologous use. This review aims to better understand the influence of diabetes on stem cell potential. For this purpose, we will first discuss the most recent advances in the mechanistic understanding of the effects of diabetes on stem cell phenotype, function, and molecular fingerprint to further elaborate on diabetes-induced alterations in stem cell extracellular vesicle profile. Although we acknowledge that multiple sources of stem or progenitor cells are used for regenerative purposes, we will focus on bone marrow hematopoietic stem/progenitor cells, mesenchymal stem cells residing in the bone marrow, and adipose tissue and briefly discuss endothelial colony-forming cells.

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.

Insulin negatively regulates dedifferentiation of mouse adipocytes in vitro

Insulin plays an important role during adipogenic differentiation of animal preadipocytes and the maintenance of mature phenotypes. However, its role and mechanism in dedifferentiation of adipocyte remains unclear. This study investigated the effects of insulin on dedifferentiation of mice adipocytes, and the potential mechanisms. The preadipocytes were isolated from the subcutaneous white adipose tissue of wild type (WT), TNFα gene mutant (TNFα-/-), leptin gene spontaneous point mutant (db/db) and TNFα-/-/db/db mice and were then induced for differentiation. Interestingly, dedifferentiation of these adipocytes occurred once removing exogenous insulin from the adipogenic medium. As characteristics of dedifferentiation of the adipocytes, downregulation of adipogenic markers, upregulation of stemness markers and loss of intracellular lipids were observed from the four genotypes. Notably, dedifferentiation was occurring earlier if the insulin signal was blocked. These dedifferentiated cells regained the potentials of the stem cell-like characteristics. There is no significant difference in the characteristics of the dedifferentiation between the adipocytes. Overall, the study provided evidence that insulin plays a negative regulatory role in the dedifferentiation of adipocytes. We also confirmed that both dedifferentiation of mouse adipocytes, and effect of the insulin on this process were independent of the cell genotypes, while it is a widespread phenomenon in the adipocytes.

Diabetes-induced glucolipotoxicity impairs wound healing ability of adipose-derived stem cells-through the miR-1248/CITED2/HIF-1α pathway

Despite being an attractive cell type for mesenchymal stem cell (MSC) transplantation therapy for wound healing, human adipose-derived stem cells (hADSCs) from diabetes mellitus (DM) patients result in remarkable retention of stem cell activity due to diabetes-induced glucolipotoxicity. We explored the effect of diabetes and medium containing AGEs on the cell activity, phenotype, multipotency, angiogenic potential, and the therapeutic effect of hADSCs. Then, miRNA-1248 was selected by miRNA microarray analysis to further study the core molecular pathways that regulate the wound healing ability of hADSCs. hADSCs isolated from DM patients or cultured in medium containing AGEs in vitro exhibited decreased effectiveness in stem cell therapy. The expression of miRNA-1248 was decreased in the hADSCs of DM patients and hence failed to positively regulate stem cell activity, differentiation functions, and angiogenesis promotion effect. This concomitantly increased the expression of CITED2, an inhibitor of HIF-1α, thus influencing growth factors that promote angiogenesis, cellular proliferation, and wound healing. Overall, our data demonstrated that the glucolipotoxicity-impaired wound healing ability of hADSCs might occur through the miR-1248/CITED2/HIF-1α pathway. MiRNA-1248 may have potential to be used as a novel therapeutic target for wound healing in DM patients or restoring the wound healing ability of diabetic hADSCs.

Platelet-rich plasma counteracts detrimental effect of high-glucose concentrations on mesenchymal stem cells from Bichat fat pad

Diabetic patients display increased risk of periodontitis and failure in bone augmentation procedures. Mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) represent a relevant advantage in tissue repair process and regenerative medicine. We isolated MSCs from Bichat's buccal fat pad (BFP) and measured the effects of glucose and PRP on cell number and osteogenic differentiation potential. Cells were cultured in the presence of 5.5-mM glucose (low glucose [LG]) or 25-mM glucose (high glucose [HG]). BFP-MSC number was significantly lower when cells were cultured in HG compared with those in LG. Following osteogenic differentiation procedures, calcium accumulation, alkaline phosphatase activity, and expression of osteogenic markers were significantly lower in HG compared with LG. Exposure of BFP-MSC to PRP significantly increased cell number and osteogenic differentiation potential, reaching comparable levels in LG and in HG. Thus, high-glucose concentrations impair BFP-MSC growth and osteogenic differentiation. However, these detrimental effects are largely counteracted by PRP.

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.

Multi-Parameter Analysis of Biobanked Human Bone Marrow Stromal Cells Shows Little Influence for Donor Age and Mild Comorbidities on Phenotypic and Functional Properties

Heterogeneous populations of human bone marrow-derived stromal cells (BMSC) are among the most frequently tested cellular therapeutics for treating degenerative and immune disorders, which occur predominantly in the aging population. Currently, it is unclear whether advanced donor age and commonly associated comorbidities affect the properties of ex vivo-expanded BMSCs. Thus, we stratified cells from adult and elderly donors from our biobank (n = 10 and n = 13, mean age 38 and 72 years, respectively) and compared their phenotypic and functional performance, using multiple assays typically employed as minimal criteria for defining multipotent mesenchymal stromal cells (MSCs). We found that BMSCs from both cohorts meet the standard criteria for MSC, exhibiting similar morphology, growth kinetics, gene expression profiles, and pro-angiogenic and immunosuppressive potential and the capacity to differentiate toward adipogenic, chondrogenic, and osteogenic lineages. We found no substantial differences between cells from the adult and elderly cohorts. As positive controls, we studied the impact of in vitro aging and inflammatory cytokine stimulation. Both conditions clearly affected the cellular properties, independent of donor age. We conclude that in vitro aging rather than in vivo donor aging influences BMSC characteristics.

Hyperglycemia Changes Expression of Key Adipogenesis Markers (C/EBPα and PPARᵞ)and Morphology of Differentiating Human Visceral Adipocytes

Disturbances in adipose tissue significantly contribute to the development of metabolic disorders, which are connected with hyperglycemia (HG) and underlain by epigenetics-based mechanisms. Therefore, we aimed to evaluate the effect of hyperglycemia on proliferating, differentiating and maturating human visceral pre/adipocytes (HPA-v). Three stages of cell culture were conducted under constant or variable glycemic conditions. Adipogenesis progress was assessed using BODIPY 505/515 staining. Lipid content typical for normal and hyperglycemic conditions of adipocytes was analyzed using Raman spectroscopy and imaging. Expression of adipogenic markers, PPARγ and C/EBPα, was determined at the mRNA and protein levels. We also examined expression of miRNAs proven to target PPARγ (miR-34a-5p) and C/EBPα (miR-137-3p), employing TaqMan Low-Density Arrays (TLDA) cards. Hyperglycemia altered morphology of differentiating HPA-v in relation to normoglycemia by accelerating the formation of lipid droplets and making their numbers and volume increase. Raman results confirmed that the qualitative and quantitative lipid composition under normal and hyperglycemic conditions were different, and that the number of lipid droplets increased in (HG)-treated cells. Expression profiles of both examined genes markedly changed either during adipogenesis under physiological and hyperglycemic conditions, orat particular stages of adipogenesis upon chronic and/or variable glycemia. Expression levels of PPARγ seemed to correspond to some expression changes of miR-34a-5p. miR-137-3p, whose expression was rather stable throughout the culture, did not seem to affect C/EBPα. Our observations revealed that chronic and intermittent hyperglycemia change the morphology of visceral pre/adipocytes during adipogenesis. Moreover, hyperglycemia may utilize miR-34a-5p to induce some expression changes in PPARγ.

PDGF-BB Carried by Endothelial Cell-Derived Extracellular Vesicles Reduces Vascular Smooth Muscle Cell Apoptosis in Diabetes

Endothelial cell-derived extracellular vesicles (CD31EVs) constitute a new entity for therapeutic/prognostic purposes. The roles of CD31EVs as mediators of vascular smooth muscle cell (VSMC) dysfunction in type 2 diabetes (T2D) are investigated herein. We demonstrated that, unlike serum-derived extracellular vesicles in individuals without diabetes, those in individuals with diabetes (D CD31EVs) boosted apoptosis resistance of VSMCs cultured in hyperglycemic condition. Biochemical analysis revealed that this effect relies on changes in the balance between antiapoptotic and proapoptotic signals: increase of bcl-2 and decrease of bak/bax. D CD31EV cargo analysis demonstrated that D CD31EVs are enriched in membrane-bound platelet-derived growth factor-BB (mbPDGF-BB). Thus, we postulated that mbPDGF-BB transfer by D CD31EVs could account for VSMC resistance to apoptosis. By depleting CD31EVs of platelet-derived growth factor-BB (PDGF-BB) or blocking the PDGF receptor β on VSMCs, we demonstrated that mbPDGF-BB contributes to D CD31EV-mediated bak/bax and bcl-2 levels. Moreover, we found that bak expression is under the control of PDGF-BB-mediated microRNA (miR)-296-5p expression. In fact, while PDGF-BB treatment recapitulated D CD31EV-mediated antiapoptotic program and VSMC resistance to apoptosis, PDGF-BB-depleted CD31EVs failed. D CD31EVs also increased VSMC migration and recruitment to neovessels by means of PDGF-BB. Finally, we found that VSMCs, from human atherosclerotic arteries of individuals with T2D, express low bak/bax and high bcl-2 and miR-296-5p levels. This study identifies the mbPDGF-BB in D CD31EVs as a relevant mediator of diabetes-associated VSMC resistance to apoptosis.

The features of adipose-derived stem cells in patients with inflammatory bowel diseases

PURPOSE

The treatment outcomes for inflammatory bowel disease (IBD) have been improving, but the development of better therapies is needed. Stem cell therapy is promising, but little is known about the differences in adipose-derived stem cells (ADSCs) between IBD patients and healthy individuals.

METHODS

ADSCs were isolated from subcutaneous adipose tissue (SAT) in IBD (Crohn's disease, 3; ulcerative colitis, 2) and non-IBD (colorectal cancer, 5; breast cancer, 1) patients. We also analyzed the effects of tumor necrosis factor (TNF)-α on murine ADSCs.

RESULTS

The numbers of stromal vascular fraction (SVF) cells per gram of SAT were 7.72 ± 3.03 × 10⁵ in IBD and 8.51 ± 8.80 × 10⁵ in non-IBD patients (p > 0.05). The proportions of ADSCs in SVF cells were 4.98 ± 2.61% in IBD and 1.02 ± 0.67% in non-IBD patients. The numbers of ADSCs per gram of SAT were 4.16 ± 2.96 × 10⁴ in IBD and 0.88 ± 1.04 × 10⁴ in non-IBD patients. The proportions and numbers of ADSCs were significantly higher in IBD patients than in non-IBD patients. TNF-α significantly facilitated the proliferation and motility of murine ADSCs.

CONCLUSION

These results showed the potential advantage of freshly isolated autologous ADSCs in IBD patients.

Effect of High Glucose Levels on White Adipose Cells and Adipokines-Fuel for the Fire

White adipocytes release adipokines that influence metabolic and vascular health. Hypertrophic obesity is associated with adipose tissue malfunctioning, leading to inflammation and insulin resistance. When pancreatic islet β cells can no longer compensate, the blood glucose concentration rises (hyperglycemia), resulting in type 2 diabetes. Hyperglycaemia may further aggravate adipose cell dysfunction in ~90% of patients with type 2 diabetes who are obese or overweight. This review will focus on the effects of high glucose levels on human adipose cells and the regulation of adipokines.

High glucose suppresses embryonic stem cell differentiation into cardiomyocytes : High glucose inhibits ES cell cardiogenesis

Background

Babies born to mothers with pregestational diabetes have a high risk for congenital heart defects (CHD). Embryonic stem cells (ESCs) are excellent in vitro models for studying the effect of high glucose on cardiac lineage specification because ESCs can be differentiated into cardiomyocytes. ESC maintenance and differentiation are currently performed under high glucose conditions, whose adverse effects have never been clarified.

Method

We investigated the effect of high glucose on cardiomyocyte differentiation from a well-characterized ESC line, E14, derived from mouse blastocysts. E14 cells maintained under high glucose (25 mM) failed to generate any beating cardiomyocytes using the hanging-drop embryonic body method. We created a glucose-responsive E14 cell line (GR-E14) through a graduated low glucose adaptation. The expression of stem cell markers was similar in the parent E14 cells and the GR-E14 cells.

Results

Glucose transporter 2 gene was increased in GR-E14 cells. When GR-E14 cells were differentiated into cardiomyocytes under low (5 mM) or high (25 mM) glucose conditions, high glucose significantly delayed the appearance and reduced the number of TNNT2 (Troponin T Type 2)-positive contracting cardiomyocytes. High glucose suppressed the expression of precardiac mesoderm markers, cardiac transcription factors, mature cardiomyocyte markers, and potassium channel proteins. High glucose impaired the functionality of ESC-derived cardiomyocytes by suppressing the frequencies of Ca²⁺ wave and contraction.

Conclusions

Our findings suggest that high glucose inhibits ESC cardiogenesis by suppressing key developmental genes essential for the cardiac program.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0446-5) contains supplementary material, which is available to authorized users.

Equine metabolic syndrome impairs adipose stem cells osteogenic differentiation by predominance of autophagy over selective mitophagy

Adipose‐derived mesenchymal stem cells (ASC) hold great promise in the treatment of many disorders including musculoskeletal system, cardiovascular and/or endocrine diseases. However, the cytophysiological condition of cells, used for engraftment seems to be fundamental factor that might determine the effectiveness of clinical therapy. In this study we investigated growth kinetics, senescence, accumulation of oxidative stress factors, mitochondrial biogenesis, autophagy and osteogenic differentiation potential of ASC isolated from horses suffered from equine metabolic syndrome (EMS). We demonstrated that EMS condition impairs multipotency/pluripotency in ASCs causes accumulation of reactive oxygen species and mitochondria deterioration. We found that, cytochrome c is released from mitochondria to the cytoplasm suggesting activation of intrinsic apoptotic pathway in those cells. Moreover, we observed up‐regulation of p21 and decreased ratio of Bcl‐2/BAX. Deteriorations in mitochondria structure caused alternations in osteogenic differentiation of ASC_EMS resulting in their decreased proliferation rate and reduced expression of osteogenic markers BMP‐2 and collagen type I. During osteogenic differentiation of ASC_EMS, we observed autophagic turnover as probably, an alternative way to generate adenosine triphosphate and amino acids required to increased protein synthesis during differentiation. Downregulation of PGC1α, PARKIN and PDK4 in differentiated ASC_EMS confirmed impairments in mitochondrial biogenesis and function. Hence, application of ASC_EMS into endocrinological or ortophedical practice requires further investigation and analysis in the context of safeness of their application.

Glyoxalase-1 Overexpression Reverses Defective Proangiogenic Function of Diabetic Adipose-Derived Stem Cells in Streptozotocin-Induced Diabetic Mice Model of Critical Limb Ischemia

Adipose‐derived stem cell (ADSC)‐based therapy is promising for critical limb ischemia (CLI) treatment, especially in patients with diabetes. However, the therapeutic effects of diabetic ADSCs (D‐ADSCs) are impaired by the diabetes, possibly through intracellular reactive oxygen species (ROS) accumulation. The objective of the present study was to detect whether overexpression of methylglyoxal‐metabolizing enzyme glyoxalase‐1 (GLO1), which reduces ROS in D‐ADSCs, can restore their proangiogenic function in a streptozotocin‐induced diabetic mice model of CLI. GLO1 overexpression in D‐ADSCs (G‐D‐ADSCs) was achieved using the lentivirus method. G‐D‐ADSCs showed a significant decrease in intracellular ROS accumulation, increase in cell viability, and resistance to apoptosis under high‐glucose conditions compared with D‐ADSCs. G‐D‐ADSCs also performed better in terms of migration, differentiation, and proangiogenic capacity than D‐ADSCs in a high‐glucose environment. Notably, these properties were restored to the same level as that of nondiabetic ADSCs under high‐glucose conditions. G‐D‐ADSC transplantation induced improved reperfusion and an increased limb salvage rate compared D‐ADSCs in a diabetic mice model of CLI. Histological analysis revealed higher microvessel densities and more G‐D‐ADSC‐incorporated microvessels in the G‐D‐ADSC group than in the D‐ADSC group, which was comparable to the nondiabetic ADSC group. Higher expression of vascular endothelial growth factor A and stromal cell‐derived factor‐1α and lower expression of hypoxia‐induced factor‐1α were also detected in the ischemic muscles from the G‐D‐ADSC group than that of the D‐ADSC group. The results of the present study have demonstrated that protection from ROS accumulation by GLO1 overexpression is effective in reversing the impaired biological function of D‐ADSCs in promoting neovascularization of diabetic CLI mice model and warrants the future clinical application of D‐ADSC‐based therapy in diabetic patients. Stem Cells Translational Medicine2017;6:261–271

High glucose-induced reactive oxygen species generation promotes stemness in human adipose-derived stem cells

BACKGROUND AIMS

Adipose-derived stem cells (ASCs) represent an important source of cell therapy to treat diabetic complications. However, hyperglycemia may alter several cellular functions, so the present study aimed to investigate the influence of a diabetic environment on the stemness and differentiation capabilities of ASCs.

METHODS

Human ASCs were obtained from subcutaneous adipose tissues of diabetic (dASCs) and nondiabetic donors (nASCs) and characterized. To reproduce an in vitro hyperglycemia environment, the nASCs were also cultured under prolonged high-glucose (HG; 4.5 g/L) or low-glucose (LG; 1.0 g/L) conditions.

RESULTS

The expression of cell surface markers in dASCs and nASC was similar and characteristic of mesenchymal stem cells. Although dASCs or HG-treated nASCs exhibited decreased proliferation, enhanced expression of the pluripotent markers Sox-2, Oct-4, and Nanog was observed. Moreover, HG-treated nASCs exhibited decreased cell migration, enhanced senescence, and significantly higher intracellular reactive oxygen species (ROS), whereas their adipogenic and osteogenic differentiation capacities remained comparable to LG-treated cells. With antioxidant treatment, HG-treated nASCs showed improved cell proliferative activity without stemness enhancement. This HG-induced biological response was associated with ROS-mediated AKT attenuation. When cultured in an appropriate induction medium, the HG-treated nASCs and dASCs exhibited enhanced potential of transdifferentiation into neuron-like cells.

DISCUSSION

Despite lower proliferative activity and higher senescence in a diabetic environment, ASCs also exhibit enhanced stemness and neurogenic transdifferentiation potential via a ROS-mediated mechanism. The information is important for future application of autologous ASCs in diabetic patients.

MiR-93 Controls Adiposity via Inhibition of Sirt7 and Tbx3

Conquering obesity has become a major socioeconomic challenge. Here, we show that reduced expression of the miR-25-93-106b cluster, or miR-93 alone, increases fat mass and, subsequently, insulin resistance. Mechanistically, we discovered an intricate interplay between enhanced adipocyte precursor turnover and increased adipogenesis. First, miR-93 controls Tbx3, thereby limiting self-renewal in early adipocyte precursors. Second, miR-93 inhibits the metabolic target Sirt7, which we identified as a major driver of in vivo adipogenesis via induction of differentiation and maturation of early adipocyte precursors. Using mouse parabiosis, obesity in mir-25-93-106b(-/-) mice could be rescued by restoring levels of circulating miRNA and subsequent inhibition of Tbx3 and Sirt7. Downregulation of miR-93 also occurred in obese ob/ob mice, and this phenocopy of mir-25-93-106b(-/-) was partially reversible with injection of miR-93 mimics. Our data establish miR-93 as a negative regulator of adipogenesis and a potential therapeutic option for obesity and the metabolic syndrome.

Obesity reduces the pro-angiogenic potential of adipose tissue stem cell-derived extracellular vesicles (EVs) by impairing miR-126 content: impact on clinical applications

BACKGROUND/OBJECTIVES

Soluble factors and cell-derived extracellular vesicles (EVs) are crucial tissue repair mediators in cell-based therapy. In the present study, we investigate the therapeutic impact of EVs released by adipose tissue-derived stem cells (ASCs) recovered from obese subjects' visceral and subcutaneous tissues.

METHODS

ASCs were recovered from 10 obese (oASCs) and 6 non-obese (nASCs) participants and characterized. In selected experiments, nASCs and oASCs were cultured with palmitic acid (PA) or high glucose (HG), respectively. EVs from obese (oEVs) and non-obese (nEVs) subjects' visceral and subcutaneous ASCs were collected after ultracentrifugation and analyzed for their cargo: microRNA-126 (miR-126), vascular endothelial growth factor (VEGF), and matrix metalloproteinase 2 (MMP-2), and for their biological effects on endothelial cells (ECs). Western blotting analysis and loss- and gain-of function experiments were performed.

RESULTS

oEVs show impaired angiogenic potential compared with nEVs. This effect depends on EV cargo: reduced content of VEGF, MMP-2 and, more importantly, miR-126. We demonstrate, using gain- and loss-of-function experiments, that this reduced miR-126 content leads to Spred1 upregulation and the inhibition of the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase pathway in ECs. We also show that PA treatment of nASCs translates into the release of EVs that recapitulate oEV cargo. Moreover, HG treatment of oASCs further reduces miR-126 EV content and EV-mediated in vitro angiogenesis. Finally, impaired pro-angiogenic potential is also detected in EVs released from obese subcutaneous adipose tissue-derived ASCs.

CONCLUSIONS

These results indicate that obesity impacts on EV pro-angiogenic potential and may raise concerns about the use of adipose tissue-derived EVs in cell-based therapy in the obese setting.

Diabetes-associated macrovascular complications: cell-based therapy a new tool?

Diabetes mellitus and its ongoing macrovascular complications represent one of the major health problems around the world. Rise in obesity and population ages correlate with the increased incidence of diabetes. This highlights the need for novel approaches to prevent and treat this pandemic. The discovery of a reservoir of stem/progenitors in bone marrow and in mesenchymal tissue has attracted interest of both biologists and clinicians. A number of preclinical and clinical trials were developed to explore their potential clinical impact, as target or vehicle, in different clinical settings, including diabetes complications. Currently, bone marrow, peripheral blood, mesenchymal, and adipose tissues have been used as stem/progenitor cell sources. However, evidences have been provided that both bone marrow and circulating progenitor cells are dysfunctional in diabetes. These observations along with the growing advantages in genetic manipulation have spurred researchers to exploit ex vivo manipulated cells to overcome these hurdles. In this article, we provide an overview of data relevant to stem-progenitors potential clinical application in revascularization and/or vascular repair. Moreover, the hurdles at using progenitor cells in diabetic patients will be also discussed.

Leptin receptor maintains cancer stem-like properties in triple negative breast cancer cells

Despite new therapies, breast cancer continues to be the second leading cause of cancer mortality in women, a consequence of recurrence and metastasis. In recent years, a population of cancer cells has been identified, called cancer stem cells (CSCs) with self-renewal capacity, proposed to underlie tumor recurrence and metastasis. We previously showed that the adipose tissue cytokine LEPTIN, increased in obesity, promotes the survival of CSCs in vivo. Here, we tested the hypothesis that the leptin receptor (LEPR), expressed in mammary cancer cells, is necessary for maintaining CSC-like and metastatic properties. We silenced LEPR via shRNA lentivirus transduction and determined that the expression of stem cell self-renewal transcription factors NANOG, SOX2, and OCT4 (POU5F1) is inhibited. LEPR-NANOG signaling pathway is conserved between species because we can rescue NANOG expression in human LEPR-silenced cells with the mouse LepR. Using a NANOG promoter GFP reporter, we showed that LEPR is enriched in NANOG promoter active (GFP+) cells. In lineage tracing studies, we showed that the GFP+ cells divide in a symmetric and asymmetric manner. LEPR-silenced MDA-MB-231 cells exhibit a mesenchymal to epithelial transition morphologically, increased E-CADHERIN and decreased VIMENTIN expression compared with control cells. Finally, LEPR-silenced cells exhibit reduced cell proliferation, self-renewal in tumor sphere assays, and tumor outgrowth in xenotransplant studies. Given the emergence of NANOG as a pro-carcinogenic protein in multiple cancers, these studies suggest that inhibition of LEPR may be a promising therapeutic approach to inhibit NANOG and thereby neutralize CSC functions.

Restoration of angiogenic capacity of diabetes-insulted mesenchymal stem cells by oxytocin

Background

Angiogenesis is the main therapeutic mechanism of cell therapy for cardiovascular diseases, but diabetes is reported to reduce the function and number of progenitor cells. Therefore, we studied the effect of streptozotocin-induced diabetes on the bone marrow-mesenchymal stem cell (MSC) function, and examined whether diabetes-impaired MSC could be rescued by pretreatment with oxytocin.

Results

MSCs were isolated and cultured from diabetic (DM) or non-diabetic (non-DM) rat, and proliferation rate was compared. DM-MSC was pretreated with oxytocin and compared with non-DM-MSC. Angiogenic capacity was estimated by tube formation and Matrigel plug assay, and therapeutic efficacy was studied in rat myocardial infarction (MI) model.

The proliferation and angiogenic activity of DM-MSC were severely impaired but significantly improved by pretreatment with oxytocin. Krüppel-like factor 2 (KLF2), a critical angiogenic factor, was dramatically reduced in DM-MSC and significantly restored by oxytocin. In the Matrigel plug assay, vessel formation of DM-BMSCs was attenuated but was recovered by oxytocin. In rat MI model, DM-MSC injection did not ameliorate cardiac injury, whereas oxytocin-pretreated DM-MSC improved cardiac function and reduced fibrosis.

Conclusions

Our results show that diabetes influenced MSC by reducing angiogenic capacity and therapeutic potential. We demonstrate the striking effect of oxytocin on stem cell dysfunction and suggest the use of oxytocin as a priming reagent in autologous stem cell therapy.