Low proliferative potential of adipose-derived stromal cells associates with hypertrophy and inflammation in subcutaneous and omental adipose tissue of patients with type 2 diabetes mellitus

White adipose tissue in type 2 diabetes and the effect of antidiabetic drugs

White adipose tissue (WAT) is highly flexible and was previously considered a passive location for energy storage. Its endocrine function has been established for several years, earning it the title of an "endocrine organ" due to its ability to secrete many adipokines that regulate metabolism. WAT is one of the core tissues that influence insulin sensitivity. Its dysfunction enhances insulin resistance and type 2 diabetes (T2D) progression. However, T2D may cause WAT dysfunction, including changes in distribution, metabolism, adipocyte hypertrophy, inflammation, aging, and adipokines and free fatty acid levels, which may exacerbate insulin resistance. This review used PubMed to search WAT dysfunction in T2D and the effects of these changes on insulin resistance. Additionally, we described and discussed the effects of antidiabetic drugs, including insulin therapy, sulfonylureas, metformin, glucose-like peptide-1 receptor agonists, thiazolidinediones, and sodium-dependent glucose transporters-2 inhibitors, on WAT parameters under T2D conditions.

TNF-α-licensed exosome-integrated titaniumaccelerated T2D osseointegration by promoting autophagy-regulated M2 macrophage polarization

Type 2 diabetes (T2D) is on a notable rise worldwide, which leads to unfavorable outcomes during implant treatments. Surface modification of implants and exosome treatment have been utilized to enhance osseointegration. However, there has been insufficient approach to improve adverse osseointegration in T2D conditions. In this study, we successfully loaded TNF-α-treated mesenchymal stem cell (MSC)-derived exosomes onto micro/nano-network titanium (Ti) surfaces. TNF-α-licensed exosome-integrated titanium (TNF-exo-Ti) effectively enhanced M2 macrophage polarization in hyperglycemic conditions, with increased secretion of anti-inflammatory cytokines and decreased secretion of pro-inflammatory cytokines. In addition, TNF-exo-Ti pretreated macrophage further enhanced angiogenesis and osteogenesis of endothelial cells and bone marrow MSCs. More importantly, TNF-exo-Ti markedly promoted osseointegration in T2D mice. Mechanistically, TNF-exo-Ti activated macrophage autophagy to promote M2 polarization through inhibition of the PI3K/AKT/mTOR pathway, which could be abolished by PI3K agonist. Thus, this study established TNF-α-licensed exosome-immobilized titanium surfaces that could rectify macrophage immune states and accelerate osseointegration in T2D conditions.

Selected microRNA Expression and Protein Regulator Secretion by Adipose Tissue-Derived Mesenchymal Stem Cells and Metabolic Syndrome

The role of adipose mesenchymal stem cells (Ad-MSCs) in metabolic syndrome remains unclear. We aimed to assess the expression of selected microRNAs in Ad-MSCs of non-diabetic adults in relation to Ad-MSC secretion of protein regulators and basic metabolic parameters. Ten obese, eight overweight, and five normal weight subjects were enrolled: 19 females and 4 males; aged 43.0 ± 8.9 years. Ad-MSCs were harvested from abdominal subcutaneous fat. Ad-MSC cellular expressions of four microRNAs (2-ΔCt values) and concentrations of IL-6, IL-10, VEGF, and IGF-1 in the Ad-MSC-conditioned medium were assessed. The expressions of miR-21, miR-122, or miR-192 did not correlate with clinical parameters (age, sex, BMI, visceral fat, HOMA-IR, fasting glycemia, HbA1c, serum lipids, CRP, and eGFR). Conversely, the expression of miR-155 was lowest in obese subjects (3.69 ± 2.67 × 10-3 vs. 7.07 ± 4.42 × 10-3 in overweight and 10.25 ± 7.05 × 10-3 in normal weight ones, p = 0.04). The expression of miR-155 correlated inversely with BMI (sex-adjusted r = -0.64; p < 0.01), visceral adiposity (r = -0.49; p = 0.03), and serum CRP (r = -0.63; p < 0.01), whereas it correlated positively with serum HDL cholesterol (r = 0.51; p = 0.02). Moreover, miR-155 synthesis was associated marginally negatively with Ad-MSC secretion of IGF-1 (r = -0.42; p = 0.05), and positively with that of IL-10 (r = 0.40; p = 0.06). Ad-MSC expression of miR-155 appears blunted in visceral obesity, which correlates with Ad-MSC IGF-1 hypersecretion and IL-10 hyposecretion, systemic microinflammation, and HDL dyslipidemia. Ad-MSC studies in metabolic syndrome should focus on miR-155.

Semaglutide 6-months therapy of type 2 diabetes mellitus restores adipose progenitors potential to develop metabolically active adipocytes

BACKGROUND

Nowadays type 2 diabetes mellitus (T2DM) leads to population mortality growth. Today glucagon-like peptide type 1 receptor agonists (GLP-1 RA) are one of the most promising glucose-lowered drugs with anorexigenic and cardioprotective effects. The present study aims to determine the effects of GLP-1 RA semaglutide 6-month therapy on T2DM patient metabolic parameters and adipose progenitor cell health.

METHODS

T2DM patients (N = 8) underwent clinical characterization and subcutaneous fat biopsy at start point and after semaglutide 6-month therapy. Adipose-derived stem cells (ADSC) were isolated by enzymatic method. Cell proliferation analysis was performed by MTT and immunocytochemistry. White and beige adipogenesis was analyzed by BODIPY493/503 staining and confocal microscopy. Adipocyte's metabolic properties were estimated by 3H- and 14C-based metabolic assays. Thermogenesis analysis was performed by ERthermAC staining and confocal microscopy. Protein markers were assessed by Western blotting.

RESULTS

Semaglutide 6-month therapy demonstrated significant anorexigenic and glucose-lowering effects. However, insulin sensitivity (HOMA-IR and M-index) was unchanged after therapy. Semaglutide 6-month therapy increased ADSC proliferation and white and beige adipogenesis. Moreover, lipid droplets fragmentation was observed in beige adipocytes. Both white and beige adipocytes after semaglutide therapy demonstrated 2-3 fold growth of glucose uptake without changes in insulin sensitivity. Newly formed white adipocytes demonstrated glucose utilization for active ATP synthesis, whereas beige adipocytes for canonical thermogenesis.

CONCLUSIONS

Our study has revealed that semaglutide 6-month therapy has not only systemic anorexigenic effects, but can markedly improve adipose tissue health. We have demonstrated critical restoration of ADSC renewal functions, which potentially can be involved in semaglutide based weight loss.

Uncovering the link between diabetes and cardiovascular diseases: insights from adipose-derived stem cells

Cardiovascular diseases (CVDs) are the leading causes of morbidity and mortality worldwide. The escalating global occurrence of obesity and diabetes mellitus (DM) has led to a significant upsurge in individuals afflicted with CVDs. As the prevalence of CVDs continues to rise, it is becoming increasingly important to identify the underlying cellular and molecular mechanisms that contribute to their development and progression, which will help discover novel therapeutic avenues. Adipose tissue (AT) is a connective tissue that plays a crucial role in maintaining lipid and glucose homeostasis. However, when AT is exposed to diseased conditions, such as DM, this tissue will alter its phenotype to become dysfunctional. AT is now recognized as a critical contributor to CVDs, especially in patients with DM. AT is comprised of a heterogeneous cellular population, which includes adipose-derived stem cells (ADSCs). ADSCs resident in AT are believed to regulate physiological cardiac function and have potential cardioprotective roles. However, recent studies have also shown that ADSCs from various adipose tissue depots become pro-apoptotic, pro-inflammatory, less angiogenic, and lose their ability to differentiate into various cell lineages upon exposure to diabetic conditions. This review aims to summarize the current understanding of the physiological roles of ADSCs, the impact of DM on ADSC phenotypic changes, and how these alterations may contribute to the pathogenesis of CVDs.

Cutaneous changes in diabetic patients: Primed for aberrant healing?

Cutaneous manifestations affect most patients with diabetes mellitus, clinically presenting with numerous dermatologic diseases from xerosis to diabetic foot ulcers (DFUs). Skin conditions not only impose a significantly impaired quality of life on individuals with diabetes but also predispose patients to further complications. Knowledge of cutaneous biology and the wound healing process under diabetic conditions is largely limited to animal models, and studies focusing on biology of the human condition of DFUs remain limited. In this review, we discuss the critical molecular, cellular, and structural changes to the skin in the hyperglycaemic and insulin-resistant environment of diabetes with a focus specifically on human-derived data. Elucidating the breadth of the cutaneous manifestations coupled with effective diabetes management is important for improving patient quality of life and averting future complications including wound healing disorders.

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.

Obesity and diabetes – are they always together?

Obesity and type 2 diabetes mellitus (DM 2) are two interrelated metabolic diseases widespread throughout the developed world. However, up to 30% of individuals with a long history of obesity do not have a carbohydrate metabolism disorder. This article presents the results of a multi-year study of adipose tissue biology in obese individuals with DM 2 compared with individuals with the same history of obesity without DM 2. Comparative analysis of hormonal, cellular, and genetic factors in two groups of patients showed that DM 2 occurs in individuals with abnormal proliferation and adipogenic differentiation of mesenchymal stem cells (MSCs) of adipose tissue. It leads to adipocyte hypertrophy and inflammatory infiltration of adipose tissue macrophages, resulting in increased insulin resistance and diabetogenic effects. These disorders are due to abnormal expression of genes responsible for the proliferation and adipogenic differentiation of MSCs. The study of the possible reversibility of abnormal changes in adipose tissue MSCs in obese patients after significant weight loss and DM 2 remission appears to be a promising research direction. The ability to control adipose tissue progenitor cells may represent a new target for treating and preventing metabolic disorders in obesity.

Type 2 Diabetes Mellitus Facilitates Shift of Adipose-Derived Stem Cells Ex Vivo Differentiation toward Osteogenesis among Patients with Obesity

Objective: Sedentary behavior with overnutrition provokes the development of obesity, insulin resistance, and type 2 diabetes mellitus (T2DM). The main progenitor cells of adipose tissue are adipose-derived stem cells (ADSCs) which can change differentiation, metabolic, and secretory phenotypes under obesity conditions. The purpose of this study was to evaluate ADSC osteogenesis activity among patients with obesity in normal glucose tolerance (NGT) and T2DM conditions. Methods: In the study, ADSCs from donors with obesity were used. After clinical characterization, all patients underwent bariatric surgery and ADSCs were isolated from subcutaneous fat biopsies. ADSCs were subjected to osteogenic differentiation, stained with Alizarin Red S, and harvested for real-time PCR and Western blotting. Cell senescence was evaluated with a β-galactosidase-activity-based assay. Results: Our results demonstrated the significantly increased calcification of ADSC on day 28 of osteogenesis in the T2DM group. These data were confirmed by the statistically significant enhancement of RUNX2 gene expression, which is a master regulator of osteogenesis. Protein expression analysis showed the increased expression of syndecan 1 and collagen I before and during osteogenesis, respectively. Moreover, T2DM ADSCs demonstrated an increased level of cellular senescence. Conclusion: We suggest that T2DM-associated cellular senescence can cause ADSC differentiation to shift toward osteogenesis, the impaired formation of new fat depots in adipose tissue, and the development of insulin resistance. The balance between ADSC adipo- and osteogenesis commitment is crucial for the determination of the metabolic fate of patients and their adipose tissue.

Electrical Stimulation of Cultured Myotubes in vitro as a Model of Skeletal Muscle Activity: Current State and Future Prospects

Skeletal muscles comprise more than a third of human body mass and critically contribute to regulation of body metabolism. Chronic inactivity reduces metabolic activity and functional capacity of muscles, leading to metabolic and other disorders, reduced life quality and duration. Cellular models based on progenitor cells isolated from human muscle biopsies and then differentiated into mature fibers in vitro can be used to solve a wide range of experimental tasks. The review discusses the aspects of myogenesis dynamics and regulation, which might be important in the development of an adequate cell model. The main function of skeletal muscle is contraction; therefore, electrical stimulation is important for both successful completion of myogenesis and in vitro modeling of major processes induced in the skeletal muscle by acute or regular physical exercise. The review analyzes the drawbacks of such cellular model and possibilities for its optimization, as well as the prospects for its further application to address fundamental aspects of muscle physiology and biochemistry and explore cellular and molecular mechanisms of metabolic diseases.

hTERT-immortalized adipose-derived stem cell line ASC52Telo demonstrates limited potential for adipose biology research

In the modern world obesity and insulin resistance contribute to a high impact on the structure of mortality. Basic research and pharmacological screenings for the search of new targets and insulin sensitizers require relevant cell models of adipocytes. Today the 3T3-L1 preadipocytes cell line is a widely used mouse-based model for investigation of adipocyte biology. Nonetheless, animal studies cannot be transferred directly in human research and nowadays the search for relevant and renewable cell models of human adipocyte is of undeniable importance. In the present study, we have compared pooled culture of human adipose-derived stem cells (ADSC) with immortalized ADSC cell line ASC52Telo. Both cell types had mesenchymal stem cell phenotype verified by flow cytometry. However, the efficacy of adipogenic differentiation, stimulation of FABP4 and PPARg protein expressions, and glucose uptake stimulation by insulin were reduced for ASC52Telo-derived adipocytes in comparison with ADSC-derived adipocytes. In addition, the analysis of insulin signaling has shown impaired phosphorylation of IRS1 and AS160 in ASC52Telo-derived cells. In summary, we have shown that immortalized cell line of human ADSC ASC52Telo have mesenchymal stem cell phenotype. Nevertheless, ASC52Telo-derived adipocytes demonstrate impaired adipogenesis and insulin sensitivity that are the main properties of healthy adipocytes.

Adipose Extracellular Vesicles: Messengers From and to Macrophages in Regulating Immunometabolic Homeostasis or Disorders

Adipose tissue is comprised of heterogenous cell populations that regulate both energy metabolism and immune reactions. Macrophages play critical roles in regulating immunometabolic homeostasis or disorders through cooperation with adipocytes, adipose tissue-derived stem cells (ADSCs) or other cells in adipose tissue. Extracellular vesicles (EVs) are recently recognized as efficient messengers for intercellular communication. Emerging evidences have demonstrated that adipose EVs are actively involved in the mutual interactions of macrophages, adipocytes and ADSCs, which produce considerable influences on immunometabolism under healthy or obese conditions. Here, we will elaborate the production and the characteristics of adipose EVs that are related to macrophages under different metabolic demands or stresses, whilst discuss the roles of these EVs in regulating local or systemic immunometabolic homeostasis or disorders in the context of adipocyte-macrophage dialogue and ADSC-macrophage interaction. Particularly, we provide a profile of dynamic adipose microenvironments based on macrophages. Adipose EVs act as the messengers between ADSCs and macrophages to maintain the balance of metabolism and immunity, while drive a vicious cycle between hypertrophic adipocytes and inflammatory macrophages to cause immunometabolic imbalance. This review may provide valuable information about the physio- or pathological roles of adipose EVs and the application of adipose EVs in the diagnosis and treatment of metabolic diseases.

Effects of metformin on adipose-derived stromal cell (ADSC) - Breast cancer cell lines interaction

AIMS

Metformin is a clinical drug administered to patients to treat type 2 diabetes mellitus that was found to be associated with a lower risk of occurrence of cancer and cancer-related death. The present study investigated the effects of metformin on human adipose-derived stromal cells (ADSC) - breast cancer cell line interactions.

MAIN METHODS

ADSCs grown from lipoaspirates were tested for growth-stimulating and migration-controlling activity on breast cancer cell lines after pretreatment with metformin. Furthermore, secreted proteins of ADSCs, phosphorylation of intracellular proteins and the effect of metformin on adipocytic differentiation of ADSCs were assayed.

KEY FINDINGS

Compared to breast cancer cell lines (4.0 ± 3.5% reduction of proliferation), 2 mM metformin significantly inhibited the proliferation of ADSC lines (19.2 ± 8.4% reduction of proliferation). This effect on ADSCs seems to be mediated by altered phosphorylation of GSK-3, CREB and PRAS40. Furthermore, treatment with metformin abolished the induction of differentiation of three ADSC lines to adipocytes. 1 and 2 mM metformin significantly impaired the migration of breast cancer cell lines MDA-MB-231 and MDA-MB-436 in scratch assays.

SIGNIFICANCE

Metformin showed low direct inhibitory effects on breast cancer cell lines at physiological concentrations but exerted a significant retardation of the growth and the adipocytic differentiation of ADSCs. Thus, the anticancer activity of metformin in breast cancer at physiological drug concentrations seems to be mediated by an indirect mechanism that lowers the supportive activity of ADSCs.

Adipose tissue macrophage burden, systemic inflammation, and insulin resistance

Adipose tissue inflammation, as defined by macrophage accumulation, is proposed to cause insulin resistance and systemic inflammation. Because the strength of this relationship for humans is unclear, we tested whether adipose tissue macrophage (ATM) burden is correlated with these health indicators. Using immunohistochemistry, we measured abdominal subcutaneous CD68+ (total ATM), CD14+ (proinflammatory/M1), and CD206+ (anti-inflammatory/M2) ATM in 97 volunteers (BMI 20-38 kg/m², in addition to body composition, adipocyte size, homeostasis model assessment of insulin resistance, ADIPO-IR, adipose tissue insulin resistance measured by palmitate, plasma lipids, TNF, and IL-6 concentrations. There were several significant univariate correlations between metabolic parameters to IL-6 and ATM per 100 adipocytes, but not ATM per gram tissue; adipocyte size was a confounding variable. We used matching strategies and multivariate regression analyses to investigate the relationships between ATM and inflammatory/metabolic parameters independent of adipocyte size. Matching approaches revealed that the groups discordant for CD206 but concordant for adipocyte size had significantly different fasting insulin and IL-6 concentrations. However, groups discordant for adipocyte size but concordent for ATM differeded in that visceral fat, plasma triglyceride, glucose, and TNF concentrations were greater in those with large adipocytes. Multivariate regression analysis indicated that indexes of insulin resistance and fasting triglycerides were predicted by body composition; the predictive value of ATM per 100 adipocytes or per gram tissue was variable between males and females. We conclude that the relationship between ATM burden and metabolic/inflammatory variables is confounded by adipocyte size/body composition and that ATM do not predict insulin resistance, systemic inflammation, or dyslipidemia. ATM may primarily play a role in tissue remodeling rather than in metabolic pathology.

Adipose-derived stem cells contribute to cardiovascular remodeling

Obesity is an independent risk factor for cardiovascular disease. Adipose tissue was initially thought to be involved in metabolism through paracrine. Recent researches discovered mesenchymal stem cells inside adipose tissue which could differentiate into vascular lineages in vitro and in vivo, participating vascular remodeling. However, there were few researches focusing on distinct characteristics and functions of adipose-derived stem cells (ADSCs) from different regions. This is the first comprehensive review demonstrating the variances of ADSCs from the perspective of their origins.

Role of MicroRNAs in the Regulation of Subcutaneous White Adipose Tissue in Individuals With Obesity and Without Type 2 Diabetes

Obesity is a high-risk factor for such comorbidities as cardiovascular disease, several types of cancer, and type 2 diabetes; however not all individuals with obesity have such complications. Approximately 20% of individuals with obesity are metabolically healthy. This study focused on differences between obese individuals with and without type 2 diabetes (T2D+ and T2D-, respectively) on the transcriptome level. Subjects included were 35 T2D- patients with obesity and 35 T2D+ patients with obesity with the same body mass index (BMI). The study was based on the transcription analysis of mRNA and microRNAs (miRs) by RNAseq. In the first step, we performed RNAseq of miRs, in the second step, we analyzed only those mRNA, which appeared targets for significant miRs from the first step. All RNAseq results were validated by qPCR. There were seven miRs differently expressed with adjusted p-value <0.1, which were confirmed by qPCR. Five among them: miR-204-5p, miR125b-5p, miR-125a-5p, miR320a, miR-99b-were upregulated in T2D+ patients with obesity, while only two miRs, miR-23b-3p, and miR197-3p, were increased in T2D- patients with obesity. These seven miRs target two groups of genes: matrix metalloproteinases and TGFβ signal pathway genes. According to the results of transcriptome analysis, the main difference between T2D+ and T2D- patients with obesity was in adipogenesis and fibrosis regulation by matrix metalloproteinases and SMAD4-RUNX2 signal cascade. Based on the data about transcription profiles of both groups, we suggested that the process of fibrosis in T2D+ patients with obesity is more pronounced than in T2D- patients with obesity.