Conditioned Media From Adipose Tissue Derived Mesenchymal Stem Cells Reverse Insulin Resistance in Cellular Models

Mesenchymal stem cells improve cardiac function in diabetic rats by reducing cardiac injury biomarkers and downregulating JAK/STAT/iNOS and iNOS/Apoptosis signaling pathways

Cardiovascular complications are prevalent manifestations of type 2 diabetes mellitus (T2DM) and are usually the main cause of death. This study aims to show the underlying mechanisms of the potential therapeutic effect of mesenchymal stem cells (MSCs) on diabetic cardiac dysfunction. Twenty-four male Wistar rats were randomly assigned to one of three groups The control group received standard laboratory chow, and the groups with T2DM received a single dose of 45 mg/kg body weight of streptozotocin (STZ) after 3 weeks of pretreatment with a high-fat diet (HFD). Eight weeks after the diagnosis of T2DM, rats were divided into two groups: the T2DM model group and the T2DM + MSCs group. BM-MSCs were administered systemically at 2 × 106 cells/rat doses. A Significant amelioration in Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and dyslipidemia was noted 2 weeks post-administration of MSCs. Administration of MSCs improved dyslipidemia, the altered cardiac injury biomarkers (p ≤ 0.0001), downregulated Janus kinase 2/signal transducer and activator of transcription 3(JAK2/STAT3)/inducible Nitric oxide synthase (iNOS) and iNOS/Apoptosis signaling pathways. This was associated with improved cardiac dysfunction (impaired left ventricular performance and decreased contractility index). Our results show that MSCs ameliorate cardiac dysfunction associated with diabetic cardiomyopathy by lowering dyslipidemia and insulin resistance, inhibiting oxidative stress, and inflammation, downregulating JAK2/STAT3/iNOS and iNOS/Apoptosis signaling pathways.

Exploring the impact of acetylsalicylic acid and conditioned medium obtained from mesenchymal cells, individually and in combination, on cognitive function, histological changes, and oxidant-antioxidant balance in male rats with hippocampal injury

BACKGROUND

The hippocampus is susceptible to damage, leading to negative impacts on cognition. Conditioned medium (CM) obtained from adipose tissue-derived mesenchymal stem cells (MSCs) and acetylsalicylic acid (ASA) have shown neuroprotective effects independently. This study explored the synergistic potential of ASA and CM from adipose-derived MSCs against hippocampal injury.

METHODS

Adult male Wistar rats received bilateral hippocampal ethidium bromide (EB) injections to induce hippocampal damage. Rats were treated with ASA and/or CM derived from adipose tissue MSCs every 48 h for 16 days. Behavioral tests (open field test, Morris water maze, novel object recognition, and passive avoidance), oxidative stress, Western blot analysis of brain-derived neurotrophic factor (BDNF) and cerebral dopamine neurotrophic factor (CDNF) expression, and hippocampal histological investigation were conducted.

RESULTS

Administration of EB caused impairments in spatial, recognition, and passive avoidance memory, as well as heightened oxidative stress, reduced BDNF/CDNF expression, and pyramidal cell loss in the hippocampal CA1 region. Administration of ASA, CM, or a combination of both mitigated these hippocampal damages and cognitive deficits, elevated BDNF and CDNF levels, and alleviated the CA1 necrosis caused by EB. Moreover, co-administering ASA and CM resulted in greater improvements in spatial memory compared to administering ASA alone, suggesting possible synergistic interactions.

CONCLUSIONS

The ability of ASA, CM obtained from adipose tissue-derived MSCs, and their combination therapy to alleviate hippocampal injuries highlights their promising therapeutic potential as a neuroprotection strategy against brain damage. Our findings provide preliminary evidence of the potential synergistic effects of ASA and CM, which warrants further investigations.

Progress and application of adipose-derived stem cells in the treatment of diabetes and its complications

Diabetes mellitus (DM) is a serious chronic metabolic disease that can lead to many serious complications, such as cardiovascular disease, retinopathy, neuropathy, and kidney disease. Once diagnosed with diabetes, patients need to take oral hypoglycemic drugs or use insulin to control blood sugar and slow down the progression of the disease. This has a significant impact on the daily life of patients, requiring constant monitoring of the side effects of medication. It also imposes a heavy financial burden on individuals, their families, and even society as a whole. Adipose-derived stem cells (ADSCs) have recently become an emerging therapeutic modality for DM and its complications. ADSCs can improve insulin sensitivity and enhance insulin secretion through various pathways, thereby alleviating diabetes and its complications. Additionally, ADSCs can promote tissue regeneration, inhibit inflammatory reactions, and reduce tissue damage and cell apoptosis. The potential mechanisms of ADSC therapy for DM and its complications are numerous, and its extensive regenerative and differentiation ability, as well as its role in regulating the immune system and metabolic function, make it a powerful tool in the treatment of DM. Although this technology is still in the early stages, many studies have already proven its safety and effectiveness, providing new treatment options for patients with DM or its complications. Although based on current research, ADSCs have achieved some results in animal experiments and clinical trials for the treatment of DM, further clinical trials are still needed before they can be applied in a clinical setting.

Secretome Derived from Mesenchymal Stem/Stromal Cells: A Promising Strategy for Diabetes and its Complications

Diabetes is a complex metabolic disease with a high global prevalence. The health and quality of life of patients with diabetes are threatened by many complications, including diabetic foot ulcers, diabetic kidney diseases, diabetic retinopathy, and diabetic peripheral neuropathy. The application of mesenchymal stem/stromal cells (MSCs) in cell therapies has been recognized as a potential treatment for diabetes and its complications. MSCs were originally thought to exert biological effects exclusively by differentiating and replacing specific impaired cells. However, the paracrine function of factors secreted by MSCs may exert additional protective effects. MSCs secrete multiple compounds, including proteins, such as growth factors, chemokines, and other cytokines; nucleic acids, such as miRNAs; and lipids, extracellular vesicles (EVs), and exosomes (Exos). Collectively, these secreted compounds are called the MSC secretome, and usage of these chemicals in cell-free therapies may provide stronger effects with greater safety and convenience. Recent studies have demonstrated positive effects of the MSC secretome, including improved insulin sensitivity, reduced inflammation, decreased endoplasmic reticulum stress, enhanced M2 polarization of macrophages, and increased angiogenesis and autophagy; however, the mechanisms leading to these effects are not fully understood. This review summarizes the current research regarding the secretome derived from MSCs, including efforts to quantify effectiveness and uncover potential molecular mechanisms in the treatment of diabetes and related disorders. In addition, limitations and challenges are also discussed so as to facilitate applications of the MSC secretome as a cell-free therapy for diabetes and its complications.

Advances in the Treatment of Kidney Disorders using Mesenchymal Stem Cells

Renal disease is a medical condition that poses a potential threat to the life of an individual and is related to substantial morbidity and mortality rates in clinical environments. The aetiology of this condition is influenced by multiple factors, and its incidence tends to increase with progressive aging. Although supportive therapy and kidney transplantation have potential advantages, they also have limitations in terms of mitigating the progression of KD. Despite significant advancements in the domain of supportive therapy, mortality rates in patients continue to increase. Due to their ability to self-renew and multidirectionally differentiate, stem cell therapy has been shown to have tremendous potential in the repair of the diseased kidney. MSCs (Mesenchymal stem cells) are a cell population that is extensively distributed and can be located in various niches throughout an individual's lifespan. The cells in question are characterised by their potential for indefinite replication and their aptitude for undergoing differentiation into fully developed cells of mesodermal origin under laboratory conditions. It is essential to emphasize that MSCs have demonstrated a favorable safety profile and efficacy as a therapeutic intervention for renal diseases in both preclinical as well as clinical investigations. MSCs have been found to slow the advancement of kidney disease, and this impact is thought to be due to their control over a number of physiological processes, including immunological response, tubular epithelial- mesenchymal transition, oxidative stress, renal tubular cell death, and angiogenesis. In addition, MSCs demonstrate recognised effectiveness in managing both acute and chronic kidney diseases via paracrine pathways. The proposal to utilise a therapy that is based on stem-cells as an effective treatment has been put forward in search of discovering novel therapies to promote renal regeneration. Preclinical researchers have demonstrated that various types of stem cells can provide advantages in acute and chronic kidney disease. Moreover, preliminary results from clinical trials have suggested that these interventions are both safe and well-tolerated. This manuscript provides a brief overview of the potential renoprotective effects of stem cell-based treatments in acute as well as chronic renal dysfunction. Furthermore, the mechanisms that govern the process of kidney regeneration induced by stem cells are investigated. This article will examine the therapeutic approaches that make use of stem cells for the treatment of kidney disorders. The analysis will cover various cellular sources that have been utilised, potential mechanisms involved, and the outcomes that have been achieved so far.

Treatment of type 2 diabetes mellitus with stem cells and antidiabetic drugs: a dualistic and future-focused approach

Type 2 Diabetes Mellitus (T2DM) accounts for more than 90% of total diabetes mellitus cases all over the world. Obesity and lack of balance between energy intake and energy expenditure are closely linked to T2DM. Initial pharmaceutical treatment and lifestyle interventions can at times lead to remission but usually help alleviate it to a certain extent and the condition remains, thus, recurrent with the patient being permanently pharmaco-dependent. Mesenchymal stromal cells (MSCs) are multipotent, self-renewing cells with the ability to secrete a variety of biological factors that can help restore and repair injured tissues. MSC-derived exosomes possess these properties of the original stem cells and are potentially able to confer superior effects due to advanced cell-to-cell signaling and the presence of stem cell-specific miRNAs. On the other hand, the repository of antidiabetic agents is constantly updated with novel T2DM disease-modifying drugs, with higher efficacy and increasingly convenient delivery protocols. Delving deeply, this review details the latest progress and ongoing studies related to the amalgamation of stem cells and antidiabetic drugs, establishing how this harmonized approach can exert superior effects in the management and potential reversal of T2DM.

Transplantation of adipose derived stem cells in diabetes mellitus; limitations and achievements

Objectives

Diabetes mellitus (DM) is a complex metabolic disease that results from impaired insulin secreting pancreatic β-cells or insulin resistance. Although available medications help control the disease, patients suffer from its complications. Therefore, finding effective therapeutic approaches to treat DM is a priority. Adipose Derived Stem Cells (ADSCs) based therapy is a promising strategy in various regenerative medicine applications, but its systematic translational use is still somewhat out of reach. This review is aimed at clarifying achievements as well as challenges facing the application of ADSCs for the treatment of DM, with a special focus on the mechanisms involved.

Methods

Literature searches were carried out on "Scopus", "PubMed" and "Google Scholar" up to September 2022 to find relevant articles in the English language for the scope of this review.

Results

Recent evidence showed a significant role of ADSC therapies in DM by ameliorating insulin resistance and hyperglycemia, regulating hepatic glucose metabolism, promoting β cell function and regeneration, and functioning as a gene delivery tool. In addition, ADSCs could improve diabetic wound healing by promoting collagen deposition, inhibiting inflammation, and enhancing angiogenesis.

Conclusion

Overall, this literature review revealed the great clinical implications of ADSCs for translating into the clinical setting for the treatment of diabetes. However, further large-scale and controlled studies are needed to overcome challenges and confirm the safety and optimal therapeutic scheme before daily clinical application.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01280-8.

Adipose-derived Mesenchymal Stem Cells Therapy as a new Treatment Option for Diabetes Mellitus

The worldwide increase in the prevalence of diabetes mellitus has raised the demand for new therapeutic strategies targeting diabetic symptoms and its chronic complications. Among different treatment options for diabetes, adipose-derived mesenchymal stem cells (ADMSCs) therapy attract the most attention. The therapeutic effects of ADMSCs are based primarily on their paracrine release of immunomodulatory, anti-inflammatory, and trophic factors. Animal models of diabetes as well as human clinical trials have shown that ADMSCs can effectively facilitate endogenous β cell regeneration, preserve residual β cell mass, reduce islet graft rejection, regulate the immune system, and ultimately improve insulin sensitivity or ameliorate insulin resistance in peripheral tissues. Nevertheless, transplantation of mesenchymal stem cells is associated with certain risks; therefore recently much attention has been devoted to ADMSCs derivatives, such as exosomes or conditioned media, as therapeutic agents for the treatment of diabetes. Compared to ADMSCs, cell-free therapy has even better therapeutic potential. This narrative review summarizes recent outcomes and molecular mechanisms of ADMSCs action in the treatment for both type 1 DM and type 2 DM, as well as shows their feasibility, benefits, and current limitations.

Sulfathiazole treats type 2 diabetes by restoring metabolism through activating CYP19A1

Globally, diabetes mellitus has been a major epidemic bringing metabolic and endocrine disorders. Currently, 1 in 11 adults suffers from diabetes mellitus, among the patients >90% contract type 2 diabetes mellitus (T2DM). Therefore, it is urgent to develop new drugs that effectively prevent and treat type 2 diabetes through new targets. With high-throughput screening, we found that sulfathiazole decreased the blood glucose and improved glucose metabolism in T2DM mice. Notably, we discovered that sulfathiazole treated T2DM by activating CYP19A1 protein to synthesize estrogen. Collectively, sulfathiazole along with CYP19A1 target bring new promise for the better therapy of T2DM.

Potent bystander effect and tumor tropism in suicide gene therapy using stem cells from human exfoliated deciduous teeth

Herpes simplex virus thymidine kinase (HSVTK)/ganciclovir (GCV) suicide gene therapy has a long history of treating malignant gliomas. Recently, stem cells from human exfoliated deciduous teeth (SHED), which are collected from deciduous teeth and have excellent harvestability, ethical aspects, and self-renewal, have been attracting attention mainly in the field of gene therapy. In the present study, we assessed SHED as a novel cellular vehicle for suicide gene therapy in malignant gliomas, as we have previously demonstrated with various cell types. SHED was transduced with the HSVTK gene (SHEDTK). In vitro experiments showed a significant bystander effect between SHEDTK and glioma cell lines in coculture. Furthermore, apoptotic changes caused by caspase 3/7 activation were simultaneously observed in SHEDTK and glioma cells. Mice implanted with a mixture of U87 and SHEDTK and treated with intraperitoneal GCV survived for longer than 100 days. Additionally, tumors in treatment model mice were significantly reduced in size during the treatment period. SHEDTK implanted at the contralateral hemisphere migrated toward the tumor crossing the corpus callosum. These results suggested that SHEDTK-based suicide gene therapy has potent tumor tropism and a bystander-killing effect, potentially offering a new promising therapeutic modality for malignant gliomas.

Using adipose-derived mesenchymal stem cells to fight the metabolic complications of obesity: Where do we stand?

Obesity is a critical risk factor for the development of metabolic diseases, and its prevalence is increasing worldwide. Stem cell-based therapies have become a promising tool for therapeutic intervention. Among them are adipose-derived mesenchymal stem cells (ADMSCs), secreting numerous bioactive molecules, like growth factors, cytokines, and chemokines. Their unique features, including immunosuppressive and immunomodulatory properties, make them an ideal candidates for clinical applications. Numerous experimental studies have shown that ADMSCs can improve pancreatic islet cell viability and function, ameliorate hyperglycemia, improve insulin sensitivity, restore liver function, counteract dyslipidemia, lower pro-inflammatory cytokines, and reduce oxidative stress in the animal models. These results prompted scientists to use ADMSCs clinically. However, up to date, there have been few clinical studies or ongoing trails using ADMSCs to treat metabolic disorders such as type 2 diabetes mellitus (T2DM) or liver cirrhosis. Most human studies have implemented autologous ADMSCs with minimal risk of cellular rejection. Because the functionality of ADMSCs is significantly reduced in subjects with obesity and/or metabolic syndrome, their efficacy is questioned. ADMSCs transplantation may offer a potential therapeutic approach for the treatment of metabolic complications of obesity, but randomized controlled trials are required to establish their safety and efficacy in humans prior to routine clinical use.

The Potential Therapeutic Effect of Orexin-Treated versus Orexin-Untreated Adipose Tissue-Derived Mesenchymal Stem Cell Therapy on Insulin Resistance in Type 2 Diabetic Rats

Type 2 diabetes mellitus is a chronic metabolic disease characterized by resistance to peripheral insulin actions. Mesenchymal stem cells have been studied for years in T2DM therapy, including adipose tissue-derived mesenchymal stem cells (AD-MSCs). Orexin neuropeptides (A and B) are well-known regulators of appetite and physical activity. The aim of this work was to elucidate the possible therapeutic effect of AD-MSC preconditioning with orexin A (OXA) on insulin resistance in rats. Twenty-eight adult male albino rats were divided into 4 equal groups: a normal control group and 3 diabetic groups (a control T2DM group, diabetic rats treated by an AD-MSCs group, and diabetic rats treated by AD-MSCs preconditioned with OXA). We noticed that the treated groups showed a significant alleviation of insulin resistance parameters as shown in lowering the serum levels of glucose, insulin, total cholesterol, inflammatory markers, and HOMA-IR as compared to the control diabetic group with more significant reduction observed in the OXA-pretreated AD-MSCs-administrated group. More improvement was also noted in the glucose uptake and GLUT-4 gene expression in the skeletal muscle and adipose tissue in the OXA-pretreated AD-MSCs-administrated group compared to the untreated diabetic group. Conclusion. Preconditioning of AD-MSCs with OXA can significantly increase their potential to reduce the insulin resistance in the rat model of T2DM.

The tissue origin of human mesenchymal stem cells dictates their therapeutic efficacy on glucose and lipid metabolic disorders in type II diabetic mice

Background

The therapeutic efficacy of mesenchymal stem cells (MSCs) of different tissue origins on metabolic disorders can be varied in many ways but remains poorly defined. Here we report a comprehensive comparison of human MSCs derived from umbilical cord Wharton’s jelly (UC-MSCs), dental pulp (PU-MSCs), and adipose tissue (AD-MSCs) on the treatment of glucose and lipid metabolic disorders in type II diabetic mice.

Methods

Fourteen-to-fifteen-week-old male C57BL/6 db/db mice were intravenously administered with human UC-MSCs, PU-MSCs, and AD-MSCs at various doses or vehicle control once every 2 weeks for 6 weeks. Metformin (MET) was given orally to animals in a separate group once a day at weeks 4 to 6 as a positive control. Body weight, blood glucose, and insulin levels were measured every week. Glucose tolerance tests (GTT) and insulin tolerance tests (ITT) were performed every 2 weeks. All the animals were sacrificed at week 6 and the blood and liver tissues were collected for biochemical and histological examinations.

Results

UC-MSCs showed the strongest efficacy in reducing fasting glucose levels, increasing fasting insulin levels, and improving GTT and ITT in a dose-dependent manner, whereas PU-MSCs showed an intermediate efficacy and AD-MSCs showed the least efficacy on these parameters. Moreover, UC-MSCs also reduced the serum low-density lipoprotein cholesterol (LDL-C) levels with the most prominent potency and AD-MSCs had only very weak effect on LDL-C. In contrast, AD-MSCs substantially reduced the lipid content and histological lesion of liver and accompanying biomarkers of liver injury such as serum aspartate transaminase (AST) and alanine aminotransferase (ALT) levels, whereas UC-MSCs and PU-MSCs displayed no or modest effects on these parameters, respectively.

Conclusions

Taken together, our results demonstrated that MSCs of different tissue origins can confer substantially different therapeutic efficacy in ameliorating glucose and lipid metabolic disorders in type II diabetes. MSCs with different therapeutic characteristics could be selected according to the purpose of the treatment in the future clinical practice.

Human amniotic mesenchymal stem cells-conditioned medium protects mice from high-fat diet-induced obesity

Background

Obesity is a metabolic disorder syndrome characterized by excessive fat accumulation that is related to many diseases. Human amniotic mesenchymal stem cells (hAMSCs) have a great potential for cell-based therapy due to their characteristics such as pluripotency, low immunogenicity, no tumorigenicity, potent paracrine effects, and no ethical concern. Recently, we observed that both hAMSCs and their conditioned medium (hAMSCs-CM) efficiently repaired skin injury, inhibited hepatocellular carcinoma, and alleviated high-fat diet (HFD)-induced diabetes. However, the effects and the underlying mechanisms of hAMSCs-CM on high-fat diet (HFD)-induced obesity were not explored.

Methods

The characteristics of hAMSCs were confirmed by flow cytometry, RT-PCR, and immunofluorescence. Obese mice were induced by administrating HFD for 15 weeks and simultaneously, the mice were intraperitoneally injected with hAMSCs-CM weekly to evaluate the effects of hAMSCs-CM on HFD-induced obesity. GTT and ITT assays were used to assess the effects of hAMSCs-CM on HFD-induced glucose tolerance and insulin resistance. The lipid accumulation and adipocytes hypertrophy in mouse adipose tissues were determined by histological staining, in which the alterations of blood lipid, liver, and kidney function were also examined. The role of hAMSCs-CM in energy homeostasis was monitored by examining the oxygen consumption (VO₂), carbon dioxide production (VCO₂), and food and water intake in mice. Furthermore, the expressions of the genes related to glucose metabolism, fatty acid β oxidation, thermogenesis, adipogenesis, and inflammation were determined by western blot analysis, RT-PCR, and immunofluorescence staining. The roles of hAMSCs-CM in adipogenesis and M1/M2 macrophage polarization were investigated with 3T3-L1 preadipocytes or RAW264.7 cells in vitro.

Results

hAMSCs-CM significantly restrained HFD-induced obesity in mice by inhibiting adipogenesis and lipogenesis, promoting energy expenditure, and reducing inflammation. The underlying mechanisms of the anti-obesity of hAMSCs-CM might be involved in inhibiting PPARγ and C/EBPα-mediated lipid synthesis and adipogenesis, promoting GLUT4-mediated glucose metabolism, elevating UCP1/PPARα/PGC1α-regulated energy expenditure, and enhancing STAT3-ARG1-mediated M2-type macrophage polarization.

Conclusion

Our studies demonstrated that hAMSCs significantly alleviated HFD-induced obesity through their paracrine effects. Obviously, our results open up an attractive therapeutic modality for the prevention and treatment of obesity and other metabolic disorders clinically.

Graphic Abstract

The cytokines, exosomes, or micro-vesicles secreted from hAMSCs significantly inhibited HFD-induced obesity in mice by inhibiting lipid production and adipogenesis, promoting energy consumption, and reducing inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02437-z.

Does TBC1D4 (AS160) or TBC1D1 Deficiency Affect the Expression of Fatty Acid Handling Proteins in the Adipocytes Differentiated from Human Adipose-Derived Mesenchymal Stem Cells (ADMSCs) Obtained from Subcutaneous and Visceral Fat Depots?

TBC1D4 (AS160) and TBC1D1 are Rab GTPase-activating proteins that play a key role in the regulation of glucose and possibly the transport of long chain fatty acids (LCFAs) into muscle and fat cells. Knockdown (KD) of TBC1D4 increased CD36/SR-B2 and FABPpm protein expressions in L6 myotubes, whereas in murine cardiomyocytes, TBC1D4 deficiency led to a redistribution of CD36/SR-B2 to the sarcolemma. In our study, we investigated the previously unexplored role of both Rab-GAPs in LCFAs uptake in human adipocytes differentiated from the ADMSCs of subcutaneous and visceral adipose tissue origin. To this end we performed a single- and double-knockdown of the proteins (TBC1D1 and TBC1D4). Herein, we provide evidence that AS160 mediates fatty acid entry into the adipocytes derived from ADMSCs. TBC1D4 KD resulted in quite a few alterations to the cellular phenotype, the most obvious of which was the shift of the CD36/SR-B2 transport protein to the plasma membrane. The above translated into an increased uptake of saturated long-chain fatty acid. Interestingly, we observed a tissue-specific pattern, with more pronounced changes present in the adipocytes derived from subADMSCs. Altogether, our data show that in human adipocytes, TBC1D4, but not TBC1D1, deficiency increases LCFAs transport via CD36/SR-B2 translocation.

Umbilical Cord-Mesenchymal Stem Cell-Conditioned Medium Improves Insulin Resistance in C2C12 Cell

BACKGROUND

Umbilical cord-mesenchymal stem cell-conditioned medium (UC-MSC-CM) has emerged as a promising cell-free therapy. The aim of this study was to explore the therapeutic effects of UC-MSC-CM on insulin resistance in C2C12 cell.

METHODS

Insulin resistance was induced by palmitate. Effects of UC-MSC-CM on insulin resistance were evaluated using glucose uptake, glucose transporter type 4 (GLUT4) translocation, the insulin-signaling pathway, and mitochondrial contents and functions in C2C12 cell.

RESULTS

Glucose uptake was improved by UC-MSC-CM. UC-MSC-CM treatment increased only in membranous GLUT4 expression, not in cytosolic GLUT4 expression. It restored the insulin-signaling pathway in insulin receptor substrate 1 and protein kinase B. Mitochondrial contents evaluated by mitochondrial transcription factor A, mitochondrial DNA copy number, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha were increased by UC-MSC-CM. In addition, UC-MSC-CM significantly decreased mitochondrial reactive oxygen species and increased fatty acid oxidation and mitochondrial membrane potential. There was no improvement in adenosine triphosphate (ATP) contents, but ATP synthesis was improved by UC-MSC-CM. Cytokine and active factor analysis of UC-MSC-CM showed that it contained many regulators inhibiting insulin resistance.

CONCLUSION

UC-MSC-CM improves insulin resistance with multiple mechanisms in C2C12 cell.

Bone Marrow-Derived Mesenchymal Stem Cells Restored High-Fat-Fed Induced Hyperinsulinemia in Rats at Early Stage of Type 2 Diabetes Mellitus

Numerous studies have proposed the transplantation of mesenchymal stem cells (MSCs) in the treatment of typical type 2 diabetes mellitus (T2DM). We aimed to find a new strategy with MSC therapy at an early stage of T2DM to efficiently prevent the progressive deterioration of organic dysfunction. Using the high-fat-fed hyperinsulinemia rat model, we found that before the onset of typical T2DM, bone marrow-derived MSCs (BM-MSCs) significantly attenuated rising insulin with decline in glucose as well as restored lipometabolic disorder and liver dysfunction. BM-MSCs also favored the histological structure recovery and proliferative capacity of pancreatic islet cells. More importantly, BM-MSC administration successfully reversed the abnormal expression of insulin resistance-related proteins including GLUT4, phosphorylated insulin receptor substrate 1, and protein kinase Akt and proinflammatory cytokines IL-6 and TNFα in liver. These findings suggested that MSCs transplantation during hyperinsulinemia could prevent most potential risks of T2DM for patients.

Antioxidative Capacity of Liver- and Adipose-Derived Mesenchymal Stem Cell-Conditioned Media and Their Applicability in Treatment of Type 2 Diabetic Rats

Type 2 diabetes mellitus (T2DM) is mainly characterized by insulin resistance and impaired insulin secretion, which cannot be reversed with existing therapeutic strategies. Using mesenchymal stem cells (MSCs), cell-based therapy has been demonstrated in displaying therapeutic effects in T2DM for their self-renewable, differentiation potential, and immunosuppressive properties and higher levels of angiogenic factors. Stem cell therapies are complicated and have a serious adverse effect including tumor formation and immunogenicity, while using mesenchymal stem cell-conditioned media (MSC-CM) significantly reduces stem cell risk, maintaining efficacy and showing significantly higher levels of growth factors, cytokines, and angiogenic factors that stimulate angiogenesis and promote fracture healing in diabetes. In the present study, we investigated the therapeutic potential of the liver and adipose MSC-CM in diabetic endothelial dysfunction compared with standard insulin therapy. Fifty adult male Sprague Dawley rats were divided equally into 5 groups as follows: control, diabetic, diabetic+insulin, diabetic+liver MSC-CM, and diabetic+adipose MSC-CM; all treatments continued for 4 weeks. Finally, we observed that liver MSC-CM therapy had the most apparent improvement in levels of blood glucose; HbA1c; AGEs; lipid panel (cholesterol, TG, LDL, HDL, and total lipids); renal function (urea, uric acid, creatinine, and total protein); liver function (AST, ALT, ALP, bilirubin, and albumin); CPK; C-peptide; HO-1; inflammatory markers including IL-6, TNF-α, and CRP; growth factors (liver and serum IGF-1); amylase; histopathological changes; pancreatic cell oxidative stress; and antioxidant markers (MDA, GSH, ROS, CAT, SOD, HO-1, and XO) toward the normal levels compared with insulin and adipose MSCs-CM. Moreover, both the liver and adipose MSC-CM relieved the hyperglycemic status by improving pancreatic islet β cell regeneration, promoting the conversion of alpha cells to beta cells, reducing insulin resistance, and protecting pancreatic tissues against oxidative stress-induced injury as well as possessing the ability to modulate immunity and angiogenesis. These results indicated that MSC-CM infusion has therapeutic effects in T2DM rats and may be a promising novel therapeutic target.

Mesenchymal stem cell conditioned medium ameliorates diabetic serum-induced insulin resistance in 3T3-L1 cells

Background

Pharmacological factors used to induce insulin resistance (IR) in in vitro models may not mimic the full in vivo features of type 2 diabetes mellitus (T2DM). This study aimed to examine the ability of diabetic serum (DS) to induce IR and investigate whether adipose-derived mesenchymal stem cell conditioned medium (ADMSC-CM) reverses DS-induced IR.

Methods

DS was obtained from newly diagnosed T2DM patients. IR was induced in differentiated 3T3-L1 cells by employing dexamethasone, tumor necrosis factor alpha (TNF-α), palmitate and DS. Glucose uptake (2-[N-[7-nitrobenz-2-oxa-1,3-diazol-4-yl] amino]-2-deoxyglucose(2-NBDG) uptake assay), intracellular levels of reactive oxygen species (ROS), and superoxide radicals (O²⁻) (fluorescence microscopy and fluorometry) were analyzed in control and experimental samples. mRNA expression of key genes involved in glucose transport and inflammation were analyzed by using reverse transcription polymerase chain reaction (RT-PCR). Pro-inflammatory cytokines and phospho-insulin receptor substrate (IRS) (Ser-307) protein expression were analyzed by fluorescence activated cell sorter analysis. Statistical significance was determined by using one-way ANOVA followed by Tukey's multiple comparison tests.

Results

ADMSC-CM significantly increased the DS-mediated decrease in 2-NBDG uptake (11.01 ± 0.50 vs. 7.20 ± 0.30, P < 0.01) and reduced DS-driven ROS (fluorescence count, 6.35 ± 0.46 vs. 9.80 ± 0.10, P < 0.01) and O²⁻ (fluorescence count, 3.00 ± 0.10 vs. 4.60 ± 0.09, P < 0.01) production. Further, the ADMSC-CM restored DS-induced down regulation GLUT4 (1.52-fold, P < 0.05) as well as the up-regulation of PPARγ (0.35-fold, P < 0.01), and IKKβ (0.37-fold, P < 0.01) mRNA, and phospho-IRS (Ser-307) protein expression compared to the baseline (median fluorescence intensity, 88,192 ± 2720 vs. 65,450 ± 3111, P < 0.01). DS induced IR, similar to the traditionally used pharmacological factors, namely dexamethasone, TNF-α, and palmitate, which can be attributed to the significantly higher pro-inflammatory cytokines levels (TNF-α (2.28 ± 0.03 pg/mL vs. 2.38 ± 0.03 pg/mL, P < 0.01), interleukin 6 (IL)-6 (1.94 ± 0.02 pg/mL vs. 2.17 ± 0.04 pg/mL, P < 0.01), IL-17 (2.16 ± 0.02 pg/mL vs. 2.22 ± 0.002 pg/mL, P < 0.05), and interferon gamma (IFN-γ) (2.07 ± 0.02 pg/mL vs. 2.15 ± 0.04 pg/mL, P < 0.05)) in DS.

Conclusions

DS can be explored as a novel inducer of IR in in vitro studies with further standardization, substituting the conventionally used pharmacological factors. Our findings also affirm the validity of ADMSC-CM as a prospective insulin sensitizer for T2DM therapy.

Treat liver to beat diabetes

Management of Type 2 Diabetes (T2DM) with existing strategies of life style and pharmaceutical interventions has gained limited success as evidenced by its uncontrolled progression. Two key organs which are involved in pathophysiology of T2DM are liver and pancreas, both are the derivatives of endoderm with common precursor. In the invertebrates, hepatopancreas performs function of both liver and pancreas. It is known that derangement in glycolysis, neoglucogenesis, and glycogenolysis lead to hyperglycemia in T2DM although insulin levels are high. Several studies have reported implication of abnormal liver function in the development of metabolic syndrome i.e. T2DM. Partial hepatectomy has been shown to improve glycemic status in animal models of diabetes. This could be because liver and pancreas share same regenerating factors. These evidences suggest that abnormal liver status can impair pancreatic beta cell function and survival along with peripheral insulin resistance. We therefore hypothesize that restoring deranged liver functions may aid in the better control and management of T2DM. If found true, it may shift current intervention strategy towards liver rather than pancreas in the treatment of T2DM.

Systemic Administration of Rejuvenated Adipose-Derived Mesenchymal Stem Cells Improves Liver Metabolism in Equine Metabolic Syndrome (EMS)- New Approach in Veterinary Regenerative Medicine

Equine metabolic syndrome (EMS) is characterized by adiposity, insulin dysregulation and increased risk for laminitis. Increased levels of specific liver enzymes in the peripheral blood are typical findings in horses diagnosed with EMS. Current management of EMS is based on caloric restriction and increased physical activity. However, new potential treatment options are arising such as the transplantation of autologous adipose stem cells (ASC). However, cytophysiological properties of ASC derived from EMS horses are impaired which strongly limits their therapeutic potential. We hypothesized, that in vitro pharmacotherapy of those cells with 5-azacytidine (AZA) and resveratrol (RES) before their clinical application can reverse the aged phenotype of those cells and improve clinical outcome of autologous therapy. A 9 year old Dutch Warmblood Horse used for driving, was presented with severe obesity, insulin resistance. After EMS diagnosis, the animal received three intravenous injections of autologous, AZA/RES treated ASCs at weekly intervals. The therapeutic effect was assessed by the analysis of liver specific enzymes in the blood. ASC-transplantation reduced levels of glutamate dehydrogenase (GLDH), gamma-glutamyltransferase (GGT), lactate dehydrogenase (LDH) and aspartate transaminase (AST). This case report demonstrates the therapeutic potential of this intervention for EMS as well as apt utility of autologous, rejuvenated ASC injections.

Conditioned medium of adipose derived Mesenchymal Stem Cells reverse insulin resistance through downregulation of stress induced serine kinases

Insulin resistance (IR) is a constituent part of Type 2 Diabetes Mellitus (T2DM). Conditioned medium from Adipose derived Mesenchymal Stem Cells (ADMSCs-CM) has been shown to reverse IR. However, its effect on cellular stress is not well established. The objective of this study was to explore the effect of ADMSCs-CM on reactive oxygen species, mitochondrial membrane potential (ΔΨm), endoplasmic reticulum (ER) stress and expression of oxidative and inflammatory stress induced serine kinases (SISK) which are pathophysiologically linked to IR. In insulin resistant, 3T3-L1 adipocytes and C2C12 myoblast cell culture models, glucose uptake was assayed by 2-NBDG uptake. Immunomodulatory cytokines, intracellular reactive oxygen species generation, ΔΨm and protein expression of JNK1, IKKβ and phospho-IRS1 (307) were analyzed using FACS. mRNA expression of ER stress markers (CHOP1 and IRE1) and SISK (JNK1, IKKβ, ERK1 and S6K1) were analyzed using RT-PCR. ADMSCs-CM effectively improve glucose uptake as evidenced by 2-NBDG uptake assay. FACS analysis showed that ADMSCs-CM possessed significantly higher levels of IL-6 and IL-10. ADMSCs-CM decreased intracellular generation of reactive oxygen species where it restored ΔΨm in C2C12 cells. ADMSCs-CM mediated reduction in ER stress was confirmed by down-regulation in CHOP1 and IRE1 mRNA expression. ADMSCs-CM treatment showed significant down-regulation of SISK mRNA expression including IKKβ, JNK, ERK and S6K1. Our results unequivocally demonstrate for the first time the mechanism of action of ADMSCs-CM in amelioration IR by reducing oxidative and inflammatory cellular stress. This study identifies SISK as potential therapeutic targets for T2DM therapy.

Effects and mechanism of stem cells from human exfoliated deciduous teeth combined with hyperbaric oxygen therapy in type 2 diabetic rats

OBJECTIVES

Mesenchymal stem cells (MSCs) are potentially ideal for type 2 diabetes treatment, owing to their multidirectional differentiation ability and immunomodulatory properties. Here we investigated whether the stem cells from human exfoliated deciduous teeth (SHED) in combination with hyperbaric oxygen (HBO) could treat type 2 diabetic rats, and explored the underlying mechanism.

METHODS

SD rats were used to generate a type 2 diabetes model, which received stem cell therapy, HBO therapy, or both together. Before and after treatment, body weight, blood glucose, and serum insulin, blood lipid, pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), and urinary proteins were measured and compared. After 6 weeks, rats were sacrificed and their organs were subjected to hematoxylin and eosin staining and immunofluorescence staining for insulin and glucagon; apoptosis and proliferation were analyzed in islet cells. Structural changes in islets were observed under an electron microscope. Expression levels of Pdx1, Ngn3, and Pax4 mRNAs in the pancreas were assessed by real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

In comparison with diabetic mice, those treated with the combination or SHE therapy showed decreased blood glucose, insulin resistance, serum lipids, and pro-inflammatory cytokines and increased body weight and serum insulin. The morphology and structure of pancreatic islets improved, as evident from an increase in insulin-positive cells and a decrease in glucagon-positive cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining of islet cells revealed the decreased apoptosis index, while Ki67 and proliferating cell nuclear antigen staining showed increased proliferation index. Pancreatic expression of Pdx1, Ngn3, and Pax4 was upregulated.

CONCLUSION

SHED combined with HBO therapy was effective for treating type 2 diabetic rats. The underlying mechanism may involve SHED-mediated increase in the proliferation and trans-differentiation of islet β-cells and decrease in pro-inflammatory cytokines and apoptosis of islets.

Human adipose tissue mesenchymal stem cells as a novel treatment modality for correcting obesity induced metabolic dysregulation

OBJECTIVE

Obesity induced metabolic dysregulation results in cluster of chronic conditions mainly hyperglycemia, hyperinsulinemia, dyslipidemia, diabetes, cardiovascular complications and insulin resistance. To investigate the effect of i.m. injection of human adipose tissue derived mesenchymal stem cells and its secretome in correcting obesity induced metabolic dysregulation in high fat diet fed obese model of mice and understand its mechanism of action.

SUBJECTS

We injected human adipose tissue derived mesenchymal stem cells (ADMSCs) suspension (CS), conditioned medium (CM) and the cell lysate (CL) intramuscularly in high fat diet (HFD)-induced C57BL/6 mice. Metformin was used as a positive control. ADMSCs were traced in vivo for its bio distribution after injection at different time points.

RESULTS

ADMSCs-treated mice exhibited remarkable decrease in insulin resistance as quantified by HOMA-IR and triglyceride glucose index with concomitant decrease in oxidized LDL and IL6 as compared with the untreated control. CS injection showed improvement in glucose tolerance and reduction in fatty infiltration in the liver, macrophage infiltration in adipose and hypertrophy of the islets resulting from HFD. Upregulation of miRNA-206, MyoD and increase in protein content of the skeletal muscle in CS-treated mice indicates plausible mechanism of action of ADMSCs treatment in ameliorating IR in HFD mice.

CONCLUSION

Of all the three treatments, CS was found to be the best. ADMSCs were found to have migrated to different organs in order to bring about the correction in dysregulated metabolism induced by obesity. Our results open up a novel treatment modality for possible therapeutic usage in human subjects by employing autologous or allogeneic ADMSCs for the better management of obesity induced metabolic dysregulation.

Applicability of adipose-derived mesenchymal stem cells in treatment of patients with type 2 diabetes

Type 2 diabetes mellitus (T2DM) is mainly characterized by insulin resistance (IR) and impaired insulin secretion. The chronic inflammatory process contributed to IR and could also hamper pancreatic β cell function. However, currently applied treatment cannot reverse β cell damage or alleviate inflammation. Mesenchymal stem cells (MSCs), the cell-based therapy for their self-renewable, differentiation potential, and immunosuppressive properties, have been demonstrated in displaying therapeutic effects in T2DM. Adipose-derived MSCs (AD-MSCs) attracted more attention due to less harvested inconvenience and ethical issues commonly accompany with bone marrow-derived MSCs (BM-MSCs) and fetal annex-derived MSCs. Both AD-MSC therapy studies and mechanism explorations in T2DM animals presented that AD-MSCs could translate to clinical application. However, hyperglycemia, hyperinsulinemia, and metabolic disturbance in T2DM are crucial for impairment of AD-MSC function, which may limit the therapeutical effects of MSCs. This review focuses on the outcomes and the molecular mechanisms of MSC therapies in T2DM which light up the hope of AD-MSCs as an innovative strategy to cure T2DM.

Mesenchymal Stem Cells-Potential Applications in Kidney Diseases

Mesenchymal stem cells constitute a pool of cells present throughout the lifetime in numerous niches, characteristic of unlimited replication potential and the ability to differentiate into mature cells of mesodermal tissues in vitro. The therapeutic potential of these cells is, however, primarily associated with their capabilities of inhibiting inflammation and initiating tissue regeneration. Owing to these properties, mesenchymal stem cells (derived from the bone marrow, subcutaneous adipose tissue, and increasingly urine) are the subject of research in the settings of kidney diseases in which inflammation plays the key role. The most advanced studies, with the first clinical trials, apply to ischemic acute kidney injury, renal transplantation, lupus and diabetic nephropathies, in which beneficial clinical effects of cells themselves, as well as their culture medium, were observed. The study findings imply that mesenchymal stem cells act predominantly through secreted factors, including, above all, microRNAs contained within extracellular vesicles. Research over the coming years will focus on this secretome as a possible therapeutic agent void of the potential carcinogenicity of the cells.

Fibroblast growth factor-1 as a mediator of paracrine effects of canine adipose tissue-derived mesenchymal stem cells on in vitro-induced insulin resistance models

Background

In the field of diabetes research, many studies on cell therapy have been conducted using mesenchymal stem cells. This research was intended to shed light on the influence of canine adipose-tissue-derived mesenchymal stem cell conditioned medium (cAT-MSC CM) on in vitro insulin resistance models that were induced in differentiated 3T3-L1 adipocytes and the possible mechanisms involved in the phenomenon.

Results

Gene expression levels of insulin receptor substrate-1 (IRS-1) and glucose transporter type 4 (GLUT4) were used as indicators of insulin resistance. Relative protein expression levels of IRS-1 and GLUT4 were augmented in the cAT-MSC CM treatment group compared to insulin resistance models, indicating beneficial effects of cAT-MSC to DM, probably by actions of secreting factors. With reference to previous studies on fibroblast growth factor-1 (FGF1), we proposed FGF1 as a key contributing factor to the mechanism of action. We added anti-FGF1 neutralizing antibody to the CM-treated insulin resistance models. As a result, significantly diminished protein levels of IRS-1 and GLUT4 were observed, supporting our assumption. Similar results were observed in glucose uptake assay.

Conclusions

Accordingly, this study advocated the potential of FGF-1 from cAT-MSC CM as an alternative insulin sensitizer and discovered a signalling factor associated with the paracrine effects of cAT-MSC.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1671-1) contains supplementary material, which is available to authorized users.

Human Mesenchymal Stem Cell Derived Exosomes Alleviate Type 2 Diabetes Mellitus by Reversing Peripheral Insulin Resistance and Relieving β-Cell Destruction

Exosomes are nanosized extracellular vesicles (EVs) that show great promise in tissue regeneration and injury repair as mesenchymal stem cell (MSC). MSC has been shown to alleviate diabetes mellitus (DM) in both animal models and clinical trials. In this study, we aimed to investigate whether exosomes from human umbilical cord MSC (hucMSC-ex) have a therapeutic effect on type 2 DM (T2DM). We established a rat model of T2DM using a high-fat diet and streptozotocin (STZ). We found that the intravenous injection of hucMSC-ex reduced blood glucose levels as a main paracrine approach of MSC. HucMSC-ex partially reversed insulin resistance in T2DM indirectly to accelerate glucose metabolism. HucMSC-ex restored the phosphorylation (tyrosine site) of the insulin receptor substrate 1 and protein kinase B in T2DM, promoted expression and membrane translocation of glucose transporter 4 in muscle, and increased storage of glycogen in the liver to maintain glucose homeostasis. HucMSC-ex inhibited STZ-induced β-cell apoptosis to restore the insulin-secreting function of T2DM. Taken together, exosomes from hucMSC can alleviate T2DM by reversing peripheral insulin resistance and relieving β-cell destruction, providing an alternative approach for T2DM treatment.

Therapeutic Effects of Adipose Stem Cells from Diabetic Mice for the Treatment of Type 2 Diabetes

To assess the potential therapeutic effects of adipose tissue-derived mesenchymal stem cells (ASCs) for the treatment of type 2 diabetes (T2D), we compared the phenotype and functionality of ASCs isolated from high-fat diet and streptozotocin (STZ)-induced T2D and the leptin receptor-deficient (db/db) mice with cells from healthy C57BL/6 mice. ASCs from T2D or db/db mice showed similar expression patterns of cellular markers and abilities to differentiate into adipocytes, osteoblasts, and chondrocytes. However, the rate of proliferation was reduced. ASCs from db/db mice secreted less hepatocyte growth factor (HGF). T2D mice receiving a single intravenous injection of T2D or db/db ASCs showed increased insulin sensitivity, reduced inflammation and fat content in adipose tissue and the liver and increased pancreatic β cell mass through 5 weeks post-infusion. Our data show that, although ASCs from T2D or db/db mice had inferior proliferative capacity compared to cells from healthy controls, improved insulin sensitivity and less β cell death was seen in T2D mice receiving mesenchymal stem cell (MSC) therapy. This study offers evidence that ASCs from diabetic donors have the potential to be used for cell therapy in the treatment of insulin resistance and T2D.

Infusion of adipose‑derived mesenchymal stem cells inhibits skeletal muscle mitsugumin 53 elevation and thereby alleviates insulin resistance in type 2 diabetic rats

It is widely accepted that infusion of mesenchymal stem cells (MSCs) ameliorates hyperglycemia by alleviating insulin resistance in rats with type 2 diabetes mellitus (T2D). However, the detailed underlying mechanisms are not clearly defined. Mitsugumin 53 (MG53) is an E3 ligase that has recently been implicated in the aggravation of insulin resistance by promoting the ubiquitinoylation of insulin receptor substrate‑1 (IRS‑1) in skeletal muscles. It was therefore hypothesized that MG53 may be involved in MSC‑mediated therapeutic effects on insulin resistance. To test this hypothesis, in the present study, T2D rat models were induced by a high‑fat diet combined with streptozotocin administration and MSC infusion was performed four times (once every 2 weeks for 8 weeks). The therapeutic effects of MSC infusion on insulin resistance were evaluated and the effect on the expression of MG53 and insulin receptor signaling elements in skeletal muscle was also investigated by immunofluorescence staining and western blotting. The results demonstrated that MSC infusion ameliorated hyperglycemia and insulin resistance in T2D rats. Furthermore, MSC infusion inhibited MG53 elevation and reversed the decreases in glucose transporter type 4, insulin receptor, IRS‑1 and phosphorylated‑AKT levels in the skeletal muscle of T2D rats. These results indicated that MSC infusion has therapeutic effects in rats and that MG53 in skeletal muscle may be a promising novel therapeutic target protein for MSC‑mediated amelioration of insulin resistance in T2D.

Determination of optimized oxygen partial pressure to maximize the liver regenerative potential of the secretome obtained from adipose-derived stem cells

BACKGROUND

A hypoxic-preconditioned secretome from stem cells reportedly promotes the functional and regenerative capacity of the liver more effectively than a control secretome. However, the optimum oxygen partial pressure (pO₂) in the cell culture system that maximizes the therapeutic potential of the secretome has not yet been determined.

METHODS

We first determined the cellular alterations in adipose tissue-derived stem cells (ASCs) cultured under different pO₂ (21%, 10%, 5%, and 1%). Subsequently, partially hepatectomized mice were injected with the secretome of ASCs cultured under different pO₂, and then sera and liver specimens were obtained for analyses.

RESULTS

Of all AML12 cells cultured under different pO₂, the AML12 cells cultured under 1% pO₂ showed the highest mRNA expression of proliferation-associated markers (IL-6, HGF, and VEGF). In the cell proliferation assay, the AML12 cells cultured with the secretome of 1% pO₂ showed the highest cell proliferation, followed by the cells cultured with the secretome of 21%, 10%, and 5% pO₂, in that order. When injected into the partially hepatectomized mice, the 1% pO₂ secretome most significantly increased the number of Ki67-positive cells, reduced serum levels of proinflammatory mediators (IL-6 and TNF-α), and reduced serum levels of liver transaminases. In addition, analysis of the liver specimens indicated that injection with the 1% pO₂ secretome maximized the expression of the intermediate molecules of the PIP3/Akt and IL-6/STAT3 signaling pathways, all of which are known to promote liver regeneration.

CONCLUSIONS

The data of this study suggest that the secretome of ASCs cultured under 1% pO₂ has the highest liver reparative and regenerative potential of all the secretomes tested here.

Mesenchymal stem cell therapy in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM), which is characterized by the combination of relative insulin deficiency and insulin resistance, cannot be reversed with existing therapeutic strategies. Transplantation of insulin-producing cells (IPCs) was once thought to be the most promising strategy for treating diabetes, but the pace from the laboratory to clinical application has been obstructed due to its drawbacks. Mesenchymal stem cells (MSCs) harbor differentiation potential, immunosuppressive properties, and anti-inflammatory effects, and they are considered an ideal candidate cell type for treatment of DM. MSC-related research has demonstrated exciting therapeutic effects in glycemic control both in vivo and in vitro, and these results now have been translated into clinical practice. However, some critical potential problems have emerged from current clinical trials. Multi-center, large-scale, double-blind, and placebo-controlled studies with strict supervision are required before MSC transplantation can become a routine therapeutic approach for T2DM. We briefly review the molecular mechanism of MSC treatment for T2DM as well as the merits and drawbacks identified in current clinical trials.