Exendin-4 enhances the differentiation of Wharton's jelly mesenchymal stem cells into insulin-producing cells through activation of various β-cell markers

A hybrid construct of decellularized matrix and fibrin for differentiating adipose stem cells into insulin-producing cells, an optimized in vitro assessment

The generation of insulin-producing cells (IPCs) is an attractive approach for replacing damaged β cells in diabetic patients. In the present work, we introduced a hybrid platform of decellularized amniotic membrane (dAM) and fibrin encapsulation for differentiating adipose tissue-derived stem cells (ASCs) into IPCs. ASCs were isolated from healthy donors and characterized. Human AM was decellularized, and its morphology, DNA, collagen, glycosaminoglycan (GAG) contents, and biocompatibility were evaluated. ASCs were subjected to four IPC differentiation methods, and the most efficient method was selected for the experiment. ASCs were seeded onto dAM, alone or encapsulated in fibrin gel with various thrombin concentrations, and differentiated into IPCs according to a method applying serum-free media containing 2-mercaptoethanol, nicotinamide, and exendin-4. PDX-1, GLUT-2 and insulin expression were evaluated in differentiated cells using real-time PCR. Structural integrity and collagen and GAG contents of AM were preserved after decellularization, while DNA content was minimized. Cultivating ASCs on dAM augmented their attachment, proliferation, and viability and enhanced the expression of PDX-1, GLUT-2, and insulin in differentiated cells. Encapsulating ASCs in fibrin gel containing 2 mg/ml fibrinogen and 10 units/ml thrombin increased their differentiation into IPCs. dAM and fibrin gel synergistically enhanced the differentiation of ASCs into IPCs, which could be considered an appropriate strategy for replacing damaged β cells.

GLP-1 Analogue-Loaded Glucose-Responsive Nanoparticles as Allies of Stem Cell Therapies for the Treatment of Type I Diabetes

Type 1 diabetes (T1D) is characterized by insufficient insulin secretion due to β-cell loss. Despite exogenous insulin administration being a lifesaving treatment, many patients still experience severe glycemic lability. For these patients, a β-cell replacement strategy through pancreas or pancreatic islet transplantation is the most physiological approach. However, donors' scarcity and the need for lifelong immunosuppressive therapy pose some challenges. This study proposes an innovative biomimetic pancreas, comprising β- and α-cells differentiated from human induced pluripotent stem cells (hiPSCs) embedded in a biofunctional matrix with glucose-responsive nanoparticles (NPs) encapsulating a glucagon-like peptide 1 (GLP-1) analogue, which aims to enhance the glucose responsiveness of differentiated β-cells. Herein, glucose-sensitive pH-responsive NPs encapsulating exenatide or semaglutide showed an average size of 145 nm, with 40% association efficiency for exenatide-loaded NPs and 55% for semaglutide-loaded NPs. Both peptides maintained their secondary structure after in vitro release and showed a similar effect on INS-1E cells' insulin secretion. hiPSCs were differentiated into β- and α-cells, and insulin-positive cells were obtained (82%), despite low glucose responsiveness, as well as glucagon-positive cells (17.5%). The transplantation of the developed system in diabetic mice showed promising outcomes since there was an increase in the survival rate of those animals. Moreover, diabetic mice transplanted with cells and exenatide showed a decrease in their glucose levels. Overall, the biomimetic pancreas developed in this work showed improvements in diabetic mice survival rate, paving the way for new cellular therapies for T1D that explore the synergy of nanomedicines and stem cell-based approaches.

The effect of diabetes mellitus on differentiation of mesenchymal stem cells into insulin-producing cells

BACKGROUND

Diabetes mellitus (DM) is a global epidemic with increasing incidences. DM is a metabolic disease associated with chronic hyperglycemia. Aside from conventional treatments, there is no clinically approved cure for DM up till now. Differentiating mesenchymal stem cells (MSCs) into insulin-producing cells (IPCs) is a promising approach for curing DM. Our study was conducted to investigate the effect of DM on MSCs differentiation into IPCs in vivo and in vitro.

METHODS

We isolated adipose-derived mesenchymal stem cells (Ad-MSCs) from the epididymal fat of normal and STZ-induced diabetic Sprague-Dawley male rats. Afterwards, the in vitro differentiation of normal-Ad-MSCs (N-Ad-MSCs) and diabetic-Ad-MSCs (DM-Ad-MSCs) into IPCs was compared morphologically then through determining the gene expression of β-cell markers including neurogenin-3 (Ngn-3), homeobox protein (Nkx6.1), musculoaponeurotic fibrosarcoma oncogene homolog A (MafA), and insulin-1 (Ins-1) and eventually, through performing glucose-stimulated insulin secretion test (GSIS). Finally, the therapeutic potential of N-Ad-MSCs and DM-Ad-MSCs transplantation was compared in vivo in STZ-induced diabetic animals.

RESULTS

Our results showed no significant difference in the characteristics of N-Ad-MSCs and DM-Ad-MSCs. However, we demonstrated a significant difference in their abilities to differentiate into IPCs in vitro morphologically in addition to β-cell markers expression, and functional assessment via GSIS test. Furthermore, the abilities of both Ad-MSCs to control hyperglycemia in diabetic rats in vivo was assessed through measuring fasting blood glucose (FBGs), body weight (BW), histopathological examination of both pancreas and liver and immunoexpression of insulin in pancreata of study groups.

CONCLUSION

Our findings reveal the effectiveness of N-Ad-MSCs in differentiating into IPCs in vitro and controlling the hyperglycemia of STZ-induced diabetic rats in vivo compared to DM-Ad-MSCs.

Silencing of forkhead box protein O-1 (FOXO-1) enhances insulin-producing cell generation from adipose mesenchymal stem cells for diabetes therapy

AIMS

Generation of mature β-cells from MSCs has been a challenge in the field of stem cell therapy of diabetes. Adipose tissue-derived mesenchymal stem cells (Ad-MSCs) have made their mark in regenerative medicine, and provide several advantages compared to other MSCs sources. Forkhead box protein O-1 (FOXO-1) is an important transcription factor for normal development of β-cells, yet its over expression in β-cells may cause glucose intolerance. In this study, we isolated, characterized Ad-MSCs from rat epididymal fat pads, differentiated these MSCs into insulin producing cells (IPCs) and studied the role of FOXO-1 in such differentiation.

MATERIALS AND METHODS

We examined the expression of FOXO-1 and its nuclear cytoplasmic localization in the generated IPCs. Afterwards we knocked down FOXO-1 using siRNA targeting FOXO-1 (siFOXO-1). The differentiated siFOXO-1 IPCs were compared to non-targeting siRNA (siNT) IPCs regarding expression of β-cell markers by qRT-PCR and western blotting, dithizone (DTZ) staining and glucose stimulated insulin secretion (GSIS).

KEY FINDINGS

Isolated Ad-MSCs exhibited all characteristics of MSCs and can generate IPCs. FOXO-1 was initially elevated during differentiation followed by a decline towards end of differentiation. FOXO-1 was dephosphorylated and localized to the nucleus upon differentiation into IPCs. Knock down of FOXO-1 improved the expression of β-cell markers in final differentiated IPCs, improved DTZ uptake and showed increased insulin secretion upon challenging with increased glucose concentration.

SIGNIFICANCE

These results portray FOXO-1 as a hindering factor of generation of IPCs whose down-regulation can generate more mature IPCs for MSCs therapy of diabetes mellitus.

The Effect of Clopidogrel and Ticagrelor on Human Adipose Mesenchymal Stem Cell Osteogenic Differentiation Potential: In Vitro Comparative Study

Ticagrelor (TICA) and clopidogrel (CLP) are extensively used antiplatelet drugs that act by antagonizing the P2Y12 receptors that are found on platelets in addition to bone cells. Aim. The purpose of this study was to investigate the effect of clopidogrel and ticagrelor on stem cells osteogenic differentiation in vitro. Methods. Human adipose-derived mesenchymal stem cells (hAd-MSCs) were divided into (1) control group, (2) osteogenic group (osteo group), (3) clopidogrel group (CLP group), and (4) ticagrelor group (TICA group). The osteogenic differentiation potential was determined by mineralization nodule formation using Alizarin Red S staining, measuring ALP enzyme activity by alkaline phosphatase assay. Quantitative determination for osteogenic markers included osteocalcin (OC); runt-related transcription factor 2 (RUNX2) performed using western blot; osteoprotegerin (OPG) using enzyme-linked immunosorbent assay (ELISA) and inflammatory markers; and tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) measured using real-time polymerase chain reaction quantitative (RT-PCR) and ELISA. Results. In comparison to all study groups, the TICA group showed significant increase in the mineralized extracellular matrix, ALP enzyme activity, and bone markers expression as RUNX2 (P < 0.0001), OC, and OPG (P < 0.05). The expression of IL-6 and TNF-α was determined by RT-qPCR and ELISA techniques. TICA and CLP significantly decreased both markers compared to the control group. The TICA group showed statistically significant lower levels of both markers (P < 0.0001) than the CLP and control groups via the ELISA technique. Conclusion. TICA may possess a positive effect on hAd-MSCs osteogenic differentiation compared to CLP.

Bone marrow stem cell-derived β-cells: New issue for diabetes cell therapy

This investigation aimed to establish the promising role of insulin-producing cells (IPCs) growing from bone marrow-mesenchymal stem cells (BM-MSCs) in relieving hyperglycemia induced in rats. BM-MSCs were differentiated into IPCs using three different protocols. The efficiency of BM-MSCs differentiation into IPCs in vitro was confirmed by detecting IPCs specific gene expression (Foxa-2, PDX-1 and Ngn-3) and insulin release assay. The in vivo study design included 3 groups of male Wistar rats; negative control group, diabetic group and IPCs-transfused group (5 ×106 cells of the most functional IPCs/rat). One month after IPCs infusion, serum glucose, insulin, c-peptide and visfatin levels as well as pancreatic glucagon level were quantified. Gene expression analysis of pancreatic Foxa-2 and Sox-17, IGF-1 and FGF-10 was done. Additionally, histological investigation of pancreatic tissue sections was performed. Our data clarified that, the most functional IPCs are those generated from BM-MSCs using differentiation protocol 3 as indicated by the significant up-regulation of Foxa-2, PDX-1 and Ngn-3 gene expression levels. These findings were further emphasized by releasing of a significant amount of insulin in response to glucose load. The transplantation of the IPCs in diabetic rats elicited significant decline in serum glucose, visfatin and pancreatic glucagon levels along with significant rise in serum insulin and c-peptide levels. Moreover, it triggered significant up-regulation in the expression levels of pancreatic Foxa-2, Sox-17, IGF-1 and FGF-10 genes versus the untreated diabetic counterpart. The histopathological examination of pancreatic tissue almost assisted the biochemical and molecular genetic analyses. These results disclose that the cell therapy holds potential to develop a new cure for DM based on the capability of BM-MSCs to generate β-cell phenotype using specific protocol.

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.

A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome

Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.

Characterization of Perinatal Stem Cell Spheroids for the Development of Cell Therapy Strategy

Type 1 diabetes mellitus (T1DM) is a complex metabolic disease characterized by a massive loss of insulin-producing cells due to an autoimmune reaction. Currently, daily subcutaneous administration of exogenous insulin is the only effective treatment. Therefore, in recent years considerable interest has been given to stem cell therapy and in particular to the use of three-dimensional (3D) cell cultures to better reproduce in vivo conditions. The goal of this study is to provide a reliable cellular model that could be investigated for regenerative medicine applications for the replacement of insulin-producing cells in T1DM. To pursue this aim we create a co-culture spheroid of amniotic epithelial cells (AECs) and Wharton's jelly mesenchymal stromal cells (WJ-MSCs) in a one-to-one ratio. The resulting co-culture spheroids were analyzed for viability, extracellular matrix production, and hypoxic state in both early- and long-term cultures. Our results suggest that co-culture spheroids are stable in long-term culture and are still viable with a consistent extracellular matrix production evaluated with immunofluorescence staining. These findings suggest that this co-culture may potentially be differentiated into endo-pancreatic cells for regenerative medicine applications in T1DM.

Tissue engineering approaches and generation of insulin-producing cells to treat type 1 diabetes

Tissue engineering (TE) has become a new effective solution to a variety of medical problems, including diabetes. Mesenchymal stem cells (MSCs), which have the ability to differentiate into endodermal and mesodermal cells, appear to be appropriate for this function. The purpose of this review was to evaluate the outcomes of various researches on the insulin-producing cells (IPCs) generation from MSCs with TE approaches to increase efficacy of type 1 diabetes treatments. The search was performed in PubMed/Medline, Scopus and Embase databases until 2021. Studies revealed that MSCs could also differentiate into IPCs under certain conditions. Therefore, a wide range of protocols have been used for this differentiation, but their effectiveness is very different. Scaffolds can provide a microenvironment that enhances the MSCs to IPCs differentiation, improves their metabolic activity and up-regulate pancreatic-specific transcription factors. They also preserve IPCs architecture and enhance insulin production as well as protect against cell death. This systematic review offers a framework for prospective research based on data. In vitro and in vivo evidence suggests that scaffold-based TE can improve the viability and function of IPCs.

Perinatal Stem Cell Therapy to Treat Type 1 Diabetes Mellitus: A Never-Say-Die Story of Differentiation and Immunomodulation

Human term placenta and other postpartum-derived biological tissues are promising sources of perinatal cells with unique stem cell properties. Among the massive current research on stem cells, one medical focus on easily available stem cells is to exploit them in the design of immunotherapy protocols, in particular for the treatment of chronic non-curable human diseases. Type 1 diabetes is characterized by autoimmune destruction of pancreatic beta cells and perinatal cells can be harnessed both to generate insulin-producing cells for beta cell replenishment and to regulate autoimmune mechanisms via immunomodulation capacity. In this study, the strong points of cells derived from amniotic epithelial cells and from umbilical cord matrix are outlined and their potential for supporting cell therapy development. From a basic research and expert stem cell point of view, the aim of this review is to summarize information regarding the regenerative medicine field, as well as describe the state of the art on possible cell therapy approaches for diabetes.

Therapeutic role of mesenchymal stem cells (MSCs) in diabetic kidney disease (DKD)

Findings of preclinical studies and recent phase I/II clinical trials have shown that mesenchymal stem cells (MSCs) play a significant role in the development of diabetic kidney disease (DKD). Thus, MSCs have attracted increasing attention as a novel regenerative therapy for kidney diseases. This review summarizes recent literature on the roles and potential mechanisms, including hyperglycemia regulation, anti-inflammation, anti-fibrosis, pro-angiogenesis, and renal function protection, of MSC-based treatment methods for DKD. This review provides novel insights into understanding the pathogenesis of DKD and guiding the development of biological therapies.

Optimization of differentiation protocols of dental tissues stem cells to pancreatic β-cells

Background

Despite the recent progress in the differentiation strategies of stem cells into pancreatic beta cell lineage, current protocols are not optimized for different cell types. The purpose of this study is to investigate and compare the ability of stem cells derived from dental pulp (DPSCs) and periodontal ligament (PDLSCs) as two anatomically different dental tissues to differentiate into pancreatic beta cells while assessing the most suitable protocol for each cell type.

Methods

DPSCs & PDLSCs were isolated and characterized morphologically and phenotypically and then differentiated into pancreatic beta cells using two protocols. Differentiated cells were assessed by qRT-PCR for the expression of pancreatic related markers Foxa-2, Sox-17, PDX-1, Ngn-3, INS and Gcg. Functional assessment of differentiation was performed by quantification of Insulin release via ELISA.

Results

Protocol 2 implementing Geltrex significantly enhanced the expression levels of all tested genes both in DPSCs & PDLSCs. Both DPSCs & PDLSCs illustrated improved response to increased glucose concentration in comparison to undifferentiated cells. Moreover, DPSCs demonstrated an advanced potency towards pancreatic lineage differentiation over PDLSCs under both protocols.

Conclusion

In conclusion, the current study reports the promising potential of dental derived stem cells in differentiating into pancreatic lineage through selection of the right protocol.

Deducing Insulin-Producing Cells from Goat Adipose Tissue-Derived Mesenchymal Stem Cells

Mesenchymal stem cell is a potent tool for regenerative medicine against control of incurable diseases in human and animals. Diabetes mellitus is one such condition marked with the blood glucose is high due to lack of insulin (INS) hormone secreted by the pancreatic cells. Rare, but sporadic, cases of dysfunctional pancreatic cells in goat as well as the promises of stem cell therapy as an off-the-shelf medicine prompted us to explore the potential of adipose-derived goat mesenchymal stem cells (AD-MSCs) to transdifferentiate into pancreatic islet-like cells. We isolated, in vitro cultured, and characterized the AD-MSCs by expression of MSC-specific markers and differentiation into multiple mesodermal lineage cells. The characterized AD-MSCs were in vitro transdifferentiated into INS-producing islet-like cells using a cocktail of glucose, nicotinamide, activin-A, exendin-4, pentagastrin, retinoic acid, and mercaptoethanol in 3 weeks. The transdifferentiated islet-like cells demonstrated the expression of pancreatic endoderm-specific transcripts PDX1, NGN3, PAX6, PAX4, ISL1, and GLUT2 as well as protein expression of pancreatic and duodenal homeobox 1 (PDX1), INS, and Islets 1 (ISL1). The islet-like cells also demonstrated the significant glucose-dependent INS release with respect to the course of transdifferentiation regime. The study envisaged to create the building material for basic research into mechanism of glucose homeostasis, which may pave road for developments in diabetes drug discovery and regenerative therapies.

Molecular Mechanism of Pancreatic β-Cell Failure in Type 2 Diabetes Mellitus

Various important transcription factors in the pancreas are involved in the process of pancreas development, the differentiation of endocrine progenitor cells into mature insulin-producing pancreatic β-cells and the preservation of mature β-cell function. However, when β-cells are continuously exposed to a high glucose concentration for a long period of time, the expression levels of several insulin gene transcription factors are substantially suppressed, which finally leads to pancreatic β-cell failure found in type 2 diabetes mellitus. Here we show the possible underlying pathway for β-cell failure. It is likely that reduced expression levels of MafA and PDX-1 and/or incretin receptor in β-cells are closely associated with β-cell failure in type 2 diabetes mellitus. Additionally, since incretin receptor expression is reduced in the advanced stage of diabetes mellitus, incretin-based medicines show more favorable effects against β-cell failure, especially in the early stage of diabetes mellitus compared to the advanced stage. On the other hand, many subjects have recently suffered from life-threatening coronavirus infection, and coronavirus infection has brought about a new and persistent pandemic. Additionally, the spread of coronavirus infection has led to various limitations on the activities of daily life and has restricted economic development worldwide. It has been reported recently that SARS-CoV-2 directly infects β-cells through neuropilin-1, leading to apoptotic β-cell death and a reduction in insulin secretion. In this review article, we feature a possible molecular mechanism for pancreatic β-cell failure, which is often observed in type 2 diabetes mellitus. Finally, we are hopeful that coronavirus infection will decline and normal daily life will soon resume all over the world.

Exendin-4 enhances osteogenic differentiation of adipose tissue mesenchymal stem cells through the receptor activator of nuclear factor-kappa B and osteoprotegerin signaling pathway

The capability of mesenchymal stem cells (MSCs) to repair bone damage and defects has long been investigated. The receptor activator of nuclear factor-kappa B (RANK), its ligand (RANKL) and the decoy receptor osteoprotegerin (OPG) axis is crucial to keep the equilibrium between osteoblastic and osteoclastic activity. Exendin-4 utilization increased bone formation and enhanced bone integrity. This study aimed to investigate the mentioned axis and determine the effect of exendin-4 upon adipose mesenchymal stem cells (Ad-MSCs) osteogenic differentiation. Ad-MSCs were isolated from rat epididymal fat, followed by characterization and then differentiation into osteocytes both in the presence or absence of exendin-4. Osteogenic differentiation was evaluated by alizarin red staining and the expression of osteogenic markers; using reverse transcriptase-quantitative polymerase chain reaction, western blotting and enzyme-linked immunoassay. MSCs derived from rat epididymal fat were isolated and characterized, along with their differentiation into osteocytes. The differentiated cells were alizarin red-stained, showing increased staining intensity upon addition of exendin-4. Moreover, the addition of exendin-4 elevated the messenger RNA expression levels of osteogenic markers; runt-related transcription factor-2 (RUNX-2), osteocalcin, and forkhead box protein O-1 while reducing the expression of the adipogenic marker peroxisome-proliferator-activated receptor-gamma. Exendin-4 addition elevated OPG levels in the supernatant of osteogenic differentiated cells. Moreover, exendin-4 elevated the protein levels of glucagon-like peptide-1 receptor and RUNX-2, while decreasing both RANK and RANKL. In conclusion, osteogenic differentiation of Ad-MSCs is associated with increased osteoblastic rather than osteoclastic activity. The findings of this study suggest that exendin-4 can enhance Ad-MSCs osteogenic differentiation partially through the RANK/RANKL/OPG axis.

Pancreatic Duct Cells Isolated From Canines Differentiate Into Beta-Like Pancreatic Islet Cells

In this study, we isolated and cultured pancreatic ductal cells from canines and revealed the possibility for using them to differentiate into functional pancreatic beta cells in vitro. Passaged pancreatic ductal cells were induced to differentiate into beta-like pancreatic islet cells using a mixture of induced factors. Differentiated pancreatic ductal cells were analyzed based on intracellular insulin granules using transmission electron microscopy, the expression of insulin and glucagon using immunofluorescence, and glucose-stimulated insulin secretion using ELISA. Our data revealed that differentiated pancreatic ductal cells not only expressed insulin and glucagon but also synthesized insulin granules and secreted insulin at different glucose concentrations. Our study might assist in the development of effective cell therapies for the treatment of type 1 diabetes mellitus in dogs.

Direct Reprogramming of Mice Skin Fibroblasts into Insulin-Producing Cells In Vitro

Transdifferentiation means mature cell conversion into other mature cells. Ethical issues, epigenetic failure, or teratoma development are found in cellular reprogramming strategies. Thus, new methods are needed. This study aimed to develop a new novel formula of chemical molecules and growth factors that differentiate skin fibroblasts into insulin-producing cells (IPCs). Newborn mice fibroblasts differentiated using four induction methods into IPCs to search for the best method. Fibroblasts, stem cells, and pancreatic markers were identified using an immunocytochemistry (ICC) assay. Insulin was measured using ELISA and dithizone (DTZ) assays. The skin fibroblasts were induced successfully into IPCs. The best method to obtain IPCs was indicated by measuring insulin concentration in differentiated cell supernatant from all induced cells by the four methods. The protein expression of the pancreatic markers of induced cells increased with time, as indicated by the ICC assay. OCT3/4 increased on day 9, after which the expression tended to decrease. DTZ-positive clusters were observed on day 16. Secreted insulin of differentiated cells was injected in streptozotocin-induced diabetic mice, which decreased blood glucose levels after injection. This study indicated an efficient new chemical method for transdifferentiating skin fibroblasts into functional IPCs, which is a promising method for diabetes mellitus therapy.

Human umbilical cord mesenchymal stem cells in type 2 diabetes mellitus: the emerging therapeutic approach

The umbilical cord has been proved to be an easy-access, reliable, and useful source of mesenchymal stem cells (MSC) for clinical applications due to its primitive, immunomodulatory, non-immunogenic, secretory and paracrine, migratory, proliferative, and multipotent properties. This set of characteristics has recently attracted great research interest in the fields of nanotechnology and regenerative medicine and cellular therapy. Accumulating evidence supports a pronounced therapeutic potential of MSC in many different pathologies, from hematology to immunology, wound-healing, tissue regeneration, and oncology. Diabetes mellitus, branded the epidemic of the century, is considered a chronic metabolic disorder, representing a major burden for health system sustainability and an important public health challenge to modern societies. The available treatments for type 2 diabetes mellitus (T2DM) still rely mainly on combinations of oral antidiabetic agents with lifestyle and nutritional adjustments. Despite the continuous development of novel and better hypoglycemic drugs, their efficacy is limited in the installment and progression of silent T2DM complications. T2DM comorbidities and mortality rates still make it a serious, common, costly, and long-term manageable disease. Recently, experimental models, preclinical observations, and clinical studies have provided some insights and preliminary promising results using umbilical cord MSCs to treat and manage diabetes. This review focuses on the latest research and applications of human-derived umbilical cord MSC in the treatment and management of T2DM, exploring and systematizing the key effects of both umbilical cord MSC and its factor-rich secretome accordingly with the major complications associated to T2DM.

Efficiency of Stem Cell (SC) Differentiation into Insulin-Producing Cells for Treating Diabetes: a Systematic Review

Over the recent years, the use of stem cells has provided a new opportunity to treat various disorders including diabetes. Stem cells are unspecialized cells with a capacity for self-renewal and differentiation into more specialized cell types. Many factors contribute to the differentiation of SCs and thus play an important role in regulating the fate of stem cells. Accordingly, a wide range of protocols has been used to differentiate SCs to insulin-producing cells but the effectiveness of SC differentiation varies. The aim of this systematic review was to evaluate the results obtained from different studies on SC differentiation for higher efficacy to treat diabetes. This search was done in PubMed, Web of Science (WOS), and Scopus using keywords “insulin-producing cell (IPC),” “pancreatic B cell,” “insulin-secreting cell,” “stem cell,” “progenitor cells,” “mother cell,” and “colony-forming unit.” Among more than 3646 papers, 32 studies were considered eligible for more evaluations. The obtained results indicated that most of the studies were performed on the mesenchymal stem cells (MSCs) derived from different tissues as compared with other types of SCs. Different evaluations of in vitro studies as well as animal models supported their role in the recovery of diabetes. In the present review, we summarize and discuss recent advances in increasing the efficiency of SC differentiation using different materials, but despite the promising results of this systematic review, further studies are needed to assess the efficiency and safety of transplantation of these cells in diabetes recovery.

Proteomic Profiling of the First Human Dental Pulp Mesenchymal Stem/Stromal Cells from Carbonic Anhydrase II Deficiency Osteopetrosis Patients

Osteopetrosis is a hereditary disorder characterized by sclerotic, thick, weak, and brittle bone. The biological behavior of mesenchymal cells obtained from osteopetrosis patients has not been well-studied. Isolated mesenchymal stem/stromal cells from dental pulp (DP-MSSCs) of recently extracted deciduous teeth from osteopetrosis (OP) patients and healthy controls (HCs) were compared. We evaluated whether the dental pulp of OP patients has a population of MSSCs with similar multilineage differentiation capability to DP-MSSCs of healthy subjects. Stem/progenitor cells were characterized using immunohistochemistry, flow cytometry, and proteomics. Our DP-MSSCs were strongly positive for CD44, CD73, CD105, and CD90. DP-MSSCs obtained from HC subjects and OP patients showed similar patterns of proliferation and differentiation as well as gene expression. Proteomic analysis identified 1499 unique proteins with 94.3% similarity in global protein fingerprints of HCs and OP patients. Interestingly, we observed subtle differences in expressed proteins of osteopetrosis disease-related in pathways, including MAPK, ERK 1/2, PI3K, and integrin, rather than in the stem cell signaling network. Our findings of similar protein expression signatures in DP-MSSCs of HC and OP patients are of paramount interest, and further in vivo validation study is needed. There is the possibility that OP patients could have their exfoliating deciduous teeth banked for future use in regenerative dentistry.

Therapeutic efficacy of umbilical cord-derived stem cells for diabetes mellitus: a meta-analysis study

BACKGROUND

Stem cell therapy provides great hope for patients with diabetes mellitus (DM). DM is a seriously alarming metabolic disease characterized by hyperglycemia and β cell dysfunction. Efficient novel therapeutic modalities to treat DM are indeed warranted. Stem cells (SC) derived from the umbilical cord specifically provide several advantages and unique characteristics being a readily available non-invasive source, with an additional credit for their banking potential. This meta-analysis study aims to provide a focused assessment for therapeutic efficacy of umbilical cord (UC)-derived SC-transplantation, namely Wharton's jelly mesenchymal stem cells (WJ-MSCs) and umbilical cord blood (UCB) for DM.

METHODS

The clinical efficacy was evaluated based on glycemic control status (reflected on HbA1c%) and β cell function (reflected on C-peptide levels), as well as the daily insulin requirement in diabetic patients after receiving UC-derived SC-transplantation compared to baseline values. Moreover, we assessed these outcome measures in patients who received such intervention compared to those who did not receive it in randomized/non-randomized controlled clinical trials. We employed a random-effects model and standardized mean difference for this meta-analysis.

RESULTS

Eleven eligible clinical studies were included; WJ-MSCs (6 studies; 172 patients including 71 controls) and UCB (5 studies; 74 patients including 15 controls). WJ-MSCs significantly improved HbA1c% (pooled-estimate - 1.085; 95%CI (- 1.513, - 0.657); p < 0.001) and C-peptide levels (pooled-estimate 1.008; 95%CI (0.475, 1.541); p < 0.001), as well as the daily insulin-requirement (pooled-estimate - 2.027; 95%CI (- 3.32, - 0.733); p = 0.002). On the contrary, UCB was found to be uniformly ineffective; HbA1c% (pooled-estimate - 0.091, 95%CI (- 0.454, 0.271); p = 0.622), significantly deteriorated C-peptide levels (pooled-estimate - 0.789; 95%CI (- 1.252, - 0.325); p < 0.001) and daily insulin-requirement (pooled-estimate 0.916; 95%CI (0.247, 1.585); p = 0.007). All these observations remained consistent when we carried out sub-group meta-analysis for T1DM and T2DM and also when we compared patients who received WJ-MSCs or UCB to controls.

CONCLUSIONS

The results of our meta-analysis provide a clear evidence for the superior efficacy of WJ-MSCs over UCB in DM. This sheds lights on the importance to consider banking of WJ-MSCs together with the well-established routine UCB-banking, especially for those with family history of DM. Additionally, further clinical studies are required to investigate therapeutic efficacy of selected/enriched UCB-derived cell populations with immunomodulatory/regenerative potential in DM.

Generation of Insulin-Producing Cells from Canine Adipose Tissue-Derived Mesenchymal Stem Cells

The potential of mesenchymal stem cells (MSCs) to differentiate into nonmesodermal cells such as pancreatic beta cells has been reported. New cell-based therapy using MSCs for diabetes mellitus is anticipated as an alternative treatment option to insulin injection or islet transplantation in both human and veterinary medicine. Several protocols were reported for differentiation of MSCs into insulin-producing cells (IPCs), but no studies have reported IPCs generated from canine MSCs. The purpose of this study was to generate IPCs from canine adipose tissue-derived MSCs (AT-MSCs) in vitro and to investigate the effects of IPC transplantation on diabetic mice in vivo. Culturing AT-MSCs with the differentiation protocol under a two-dimensional culture system did not produce IPCs. However, spheroid-like small clusters consisting of canine AT-MSCs and human recombinant peptide μ-pieces developed under a three-dimensional (3D) culture system were successfully differentiated into IPCs. The generated IPCs under 3D culture condition were stained with dithizone and anti-insulin antibody. Canine IPCs also showed gene expression typical for pancreatic beta cells and increased insulin secretion in response to glucose stimulation. The blood glucose levels in streptozotocin-induced diabetic mice were decreased after injection with the supernatant of canine IPCs, but the hyperglycemic states of diabetic mice were not improved after transplanting IPCs subcutaneously or intramesenterically. The histological examination showed that the transplanted small clusters of IPCs were successfully engrafted to the mice and included cells positive for insulin by immunofluorescence. Several factors, such as the transplanted cell number, the origin of AT-MSCs, and the differentiation protocol, were considered potential reasons for the inability to improve the hyperglycemic state after IPC transplantation. These findings suggest that canine AT-MSCs can be differentiated into IPCs under a 3D culture system and IPC transplantation may be a new treatment option for dogs with diabetes mellitus.

A change in the zinc ion concentration reflects the maturation of insulin-producing cells generated from adipose-derived mesenchymal stem cells

The generation of insulin-producing cells (IPCs) from pluripotent stem cells could be a breakthrough treatment for type 1 diabetes. However, development of new techniques is needed to exclude immature cells for clinical application. Dithizone staining is used to evaluate IPCs by detecting zinc. We hypothesised that zinc ion (Zn2+) dynamics reflect the IPC maturation status. Human adipose-derived stem cells were differentiated into IPCs by our two-step protocol using two-dimensional (2D) or 3D culture. The stimulation indexes of 2D -and 3D-cultured IPCs on day 21 were 1.21 and 3.64 (P < 0.05), respectively. The 3D-cultured IPCs were stained with dithizone during culture, and its intensity calculated by ImageJ reached the peak on day 17 (P < 0.05). Blood glucose levels of streptozotocin-induced diabetic nude mice were normalised (4/4,100%) after transplantation of 96 3D-cultured IPCs. Zn2+ concentration changes in the medium of 3D cultures had a negative value in the early period and a large positive value in the latter period. This study suggests that Zn2+ dynamics based on our observations and staining of zinc transporters have critical roles in the differentiation of IPCs, and that their measurement might be useful to evaluate IPC maturation as a non-destructive method.

Exendin-4 promotes the vascular smooth muscle cell re-differentiation through AMPK/SIRT1/FOXO3a signaling pathways

BACKGROUND AND AIMS

The phenotype switching of vascular smooth muscle cells (VSMCs) plays a key role during development and progression of vascular remodeling diseases. Recent studies show that GLP-1 can inhibit intima thickening to delay the progression of atherosclerotic plaques. The purpose of this study was to investigate the role of Exendin-4, a GLP-1 receptor agonist, in VSMCs phenotype switching and the related mechanisms.

METHODS

Immunohistochemistry and Western blot were used to detect the effect of Exendin-4 on expression of markers of contractile VSMCs. Phalloidin staining was performed to observe the effect of Exendin-4 on morphology of VSMCs.

RESULTS

Exendin-4 significantly increased the protein levels of contractile VSMCs markers like Calponin and SM22α. After treatment of Exendin-4, VSMCs showed more typical characteristic spindle shape. In addition, Exendin-4 significantly upregulated the phosphorylation of AMPK as well as the protein levels of Sirtuin1 (SIRT1) and FOXO3a in VSMCs. After inhibiting AMPK activity with compound C and SIRT1 activity with EX527, and knocking down FOXO3a expression through RNAi technique, Exendin-4 increased the protein levels of Calponin and SM22α and promoted the redifferentiation of VSMCs mainly through AMPK/SIRT1/FOXO3a signaling pathways.

CONCLUSIONS

Exendin-4 can regulate the phenotype switching of VSMCs and promote redifferentiation of VSMCs through AMPK/SIRT1/FOXO3a signaling pathways.

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.

Potential differentiation of islet-like cells from pregnant cow-derived placental stem cells

OBJECTIVE

Type 1 diabetes is an autoimmune disease that destroys islet cells and results in insufficient insulin secretion by pancreatic β-cells. Islet transplantation from donors is an approach used for treating patients with diabetes; however, this therapy is difficult to implement because of the lack of donors. Nevertheless, several stem cells have the potential to differentiate from islet-like cells and enable insulin secretion for treating diabetes in animal models. For example, placenta is considered a waste material and can be harvested noninvasively during delivery without ethical or moral concerns. To date, the differentiation of islet-like cells from cow-derived placental stem cells (CPSCs) has yet to be demonstrated.

MATERIALS AND METHODS

The investigation of potential differentiation of islet-like cells from CPSCs was conducted by supplementation with nicotinamide, exendin-4, glucose, and poly-d-lysine and was detected through reverse transcription polymerase chain reaction, dithizone staining, and immunocytochemical methods.

RESULTS

Our results indicated that CPSCs are established and express mesenchymal stem cell surface antigen markers, such as CD73, CD166, β-integrin, and Oct-4, but not hematopoietic stem cell surface antigen markers, such as CD45. After induction, the CPSCs successfully differentiated into islet-like cells. The CPSC-derived islet-like cells expressed islet cell development-related genes, such as insulin, glucagon, pax-4, Nkx6.1, pax-6, and Fox. Moreover, CPSC-derived islet-like cells can be stained with zinc ions, which are widely distributed in the islet cells and enable insulin secretion.

CONCLUSION

Altogether, islet-like cells have the potential to be differentiated from CPSCs without gene manipulation, and can be used in diabetic animal models in the future for preclinical and drug testing trial investigations.

Obestatin can potentially differentiate Wharton's jelly mesenchymal stem cells into insulin-producing cells

In vitro-generation of β-cells from Wharton's jelly mesenchymal stem cells (WJ-MSCs) could provide a potential basis for diabetes mellitus cell therapy. However, the generation of functional insulin-producing cells (IPCs) from WJ-MSCs remains a challenge. Recently, obestatin, a gut hormone, was found to promote β-cell generation from pancreatic precursor cells. Accordingly, we hypothesize that obestatin can induce the differentiation of WJ-MSCs into IPCs. Therefore, the purpose of the current study is to examine the ability of obestatin to generate IPCs in comparison to well-known extrinsic factors that are commonly used in IPCs differentiation protocols from MSCs, namely exendin-4 and glucagon-like peptide-1 (GLP-1). To achieve our aims, WJ-MSCs were isolated, cultured and characterized by immunophenotyping and adipocytes differentiation. Afterwards, WJ-MSCs were induced to differentiate into IPCs using two differentiation protocols incorporating either exendin-4, GLP-1 or obestatin. The pancreatic progenitor marker, nestin and β-cell differentiation markers were assessed by qRT-PCR, while the functionality of the generated IPCs was assessed by glucose-stimulated insulin secretion (GSIS). Our results showed that WJ-MSCs exhibit all the characteristics of MSCs. Interestingly, using obestatin in both the short and long differentiation protocols managed to induce the expression of β-cell markers, similar to exendin-4. In GSIS, IPCs generated using either GLP-1 or obestatin showed higher secretion of insulin as compared to those generated using exendin-4 under low-glucose conditions but failed to show a significant response to increased glucose. These results indicate obestatin can be considered as a novel potential factor to consider for generation of IPCs from WJ-MSCs.

Repression of COUP-TFI Improves Bone Marrow-Derived Mesenchymal Stem Cell Differentiation into Insulin-Producing Cells

Identifying molecular mechanisms that regulate insulin expression in bone marrow-derived mesenchymal stem cells (bmMSCs) can provide clues on how to stimulate the differentiation of bmMSCs into insulin-producing cells (IPCs), which can be used as a therapeutic approach against type 1 diabetes (T1D). As repression factors may inhibit differentiation, the efficiency of this process is insufficient for cell transplantation. In this study, we used the mouse insulin 2 (Ins2) promoter sequence and performed a DNA affinity precipitation assay combined with liquid chromatography-mass spectrometry to identify the transcription factor, chicken ovalbumin upstream promoter transcriptional factor I (COUP-TFI). Functionally, bmMSCs were reprogrammed into IPCs via COUP-TFI suppression and MafA overexpression. The differentiated cells expressed higher levels of genes specific for islet endocrine cells, and they released C-peptide and insulin in response to glucose stimulation. Transplantation of IPCs into streptozotocin-induced diabetic mice caused a reduction in hyperglycemia. Mechanistically, COUP-TFI bound to the DR1 (direct repeats with 1 spacer) element in the Ins2 promoter, thereby negatively regulating promoter activity. Taken together, the data provide a novel mechanism by which COUP-TFI acts as a negative regulator in the Ins2 promoter. The differentiation of bmMSCs into IPCs could be improved by knockdown of COUP-TFI, which may provide a novel stem cell-based therapy for T1D.