The antidiabetic effect of MSCs is not impaired by insulin prophylaxis and is not improved by a second dose of cells

The ameliorating effects of mesenchymal stem cells compared to α-tocopherol on apoptosis and autophagy in streptozotocin-induced diabetic rats: Implication of PI3K/Akt signaling pathway and entero-insular axis

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are considered a novel regenerative therapy that holds much potential. This study aimed to examine and compare the ameliorative effects of BM-MSCs compared to α-tocopherol (α-Toc) on apoptosis, autophagy, and β-cell function in a rat model of streptozotocin (STZ)-induced diabetes and further analyzed the implications and interrelations of the entero-insular axis, and type I phosphoinositide 3-kinase (PI3K)/Akt signaling. Forty adult male albino rats were categorized into four groups (n = 10, in each): control group, STZ-induced diabetic group (single i.p. injection of STZ 45 mg/kg), diabetic and treated with BM-MSCs injection, diabetic and treatment with α-Toc p.o. The serum glucose, insulin, nitric oxide (NO), and catalase (CAT) were measured. Histopathological examination of the pancreas, the expression levels of insulin, CD44, caspase-3, autophagy markers, P13K/Akt, and pancreas/duodenum homeobox protein 1, in pancreatic tissue, and glucose-dependent insulinotropic polypeptide (GIP) in the duodenum were detected by hematoxylin and eosin staining, immunofluorescence labeling, and by quantitative real-time polymerase chain reaction. The diabetic rats showed reduced insulin, hyperglycemia, nitrosative stress (NO, CAT), augmented apoptosis (caspase 3), impaired autophagy (p62/SQSTM1, LC3), downregulated PI3K/Akt pathway and increased GIP expression, and degeneration of pancreatic islets. Treatment with either BM-MSCs or α-Toc suppressed the nitrosative stress, reduced apoptosis, recovered autophagy, upregulated PI3K/Akt pathway, and subsequently increased insulin levels, decreased blood glucose, and downregulated GIP expression with partial restoration of pancreatic islets. Based on our findings, the cytoprotective effects of BM-MSCs and α-Toc in type 1-induced diabetes appeared to be related to repaired autophagy and recovered PI3K/Akt signaling. Moreover, we reported their novel effects on reversing intestinal GIP expression level. The effect of BM-MSCs was notably superior to that of α-Toc.

Osteogenesis of bone marrow mesenchymal stem cell in hyperglycemia

Diabetes mellitus (DM) has been shown to be a clinical risk factor for bone diseases including osteoporosis and fragility. Bone metabolism is a complicated process that requires coordinated differentiation and proliferation of bone marrow mesenchymal stem cells (BMSCs). Owing to the regenerative properties, BMSCs have laid a robust foundation for their clinical application in various diseases. However, mounting evidence indicates that the osteogenic capability of BMSCs is impaired under high glucose conditions, which is responsible for diabetic bone diseases and greatly reduces the therapeutic efficiency of BMSCs. With the rapidly increasing incidence of DM, a better understanding of the impacts of hyperglycemia on BMSCs osteogenesis and the underlying mechanisms is needed. In this review, we aim to summarize the current knowledge of the osteogenesis of BMSCs in hyperglycemia, the underlying mechanisms, and the strategies to rescue the impaired BMSCs osteogenesis.

Efficiency of Bone Marrow-Derived Mesenchymal Stem Cells and Hesperetin in the Treatment of Streptozotocin-Induced Type 1 Diabetes in Wistar Rats

Type 1 diabetes mellitus (T1DM) was established to be ameliorated by islet transplantation, but the shortage of the transplanted human islet tissue and the use of immunosuppressive drugs to inhibit the rejection of allogeneic grafts make this type of therapy is limited. Nowadays, therapy with stem cells is one of the most promising future treatments. This kind of therapy could have a profound impact on both replacement, as well as regenerative therapies, to improve or even cure various disorders, including diabetes mellitus. Flavonoids have also been shown to possess anti-diabetic effects. Thus, this study aims to evaluate the effectiveness of the bone marrow-derived mesenchymal stem cells (BM-MSCs) and hesperetin in the treatment of a T1DM rat model. T1DM was induced in male Wistar rats that had been starved for 16 h via intraperitoneal injection of STZ at a dose of 40 mg/kg body weight (b.wt.). After 10 days of STZ injection, the diabetic rats were allocated into four groups. The first diabetic animal group was considered a diabetic control, while the other three diabetic animal groups were treated for six weeks, respectively, with hesperetin (given orally at a dose of 20 mg/kg b.wt.), BM-MSCs (injected intravenously at a dose of 1 × 10⁶ cells/rat/week), and their combination (hesperetin and BM-MSCs). The use of hesperetin and BM-MSCs in the treatment of STZ-induced diabetic animals significantly improved the glycemic state, serum fructosamine, insulin and C-peptide levels, liver glycogen content, glycogen phosphorylase, glucose-6-phosphatase activities, hepatic oxidative stress, and mRNA expressions of NF-κB, IL-1β, IL-10, P53, and Bcl-2 in pancreatic tissue. The study suggested the therapy with both hesperetin and BM-MSCs produced marked antihyperglycemic effects, which may be mediated via their potencies to ameliorate pancreatic islet architecture and insulin secretory response, as well as to decrease hepatic glucose output in diabetic animals. The improvement effects of hesperetin and BM-MSCs on the pancreatic islets of diabetic rats may be mediated via their antioxidant, anti-inflammatory, and antiapoptotic actions.

Mesenchymal stem cell treatment for enteric neuropathy in the Winnie mouse model of spontaneous chronic colitis

Inflammatory bowel disease (IBD) is a chronic gut inflammation with periods of acute flares and remission. Beneficial effects of a single dose of mesenchymal stem cell (MSC)-based treatment have been demonstrated in acute models of colitis. No studies investigated therapeutic effects of MSCs for the attenuation of enteric neuropathy in a chronic model of colitis. The short and long-term effects of MSC treatment in modulating inflammation and damage to the enteric nervous system (ENS) were studied in the Winnie mouse model of spontaneous chronic colitis highly representative of human IBD. Winnie mice received a single dose of either 1 × 10⁶ human bone marrow-derived MSCs or 100µL PBS by intracolonic enema. C57BL/6 mice received 100µL PBS. Colon tissues were collected at 3 and 60 days post MSC administration to evaluate the short-term and long-term effects of MSCs on inflammation and enteric neuropathy by histological and immunohistochemical analyses. In a separate set of experiments, multiple treatments with 4 × 10⁶ and 2 × 10⁶ MSCs were performed and tissue collected at 3 days post treatment. Chronic intestinal inflammation in Winnie mice was associated with persistent diarrhea, perianal bleeding, morphological changes, and immune cell infiltration in the colon. Significant changes to the ENS, including impairment of cholinergic, noradrenergic and sensory innervation, and myenteric neuronal loss were prominent in Winnie mice. Treatment with a single dose of bone marrow-derived MSCs was ineffective in attenuating chronic inflammation and enteric neuropathy in Winnie.

Combined Treatment with Bone Marrow-Derived Mesenchymal Stem Cells and Exendin-4 Promotes Islet Regeneration in Streptozotocin-Induced Diabetic Rats

This study was designed to assess whether the combination of the glucagon-like peptide-1 (GLP-1) analog exendin-4 (Ex4) and bone marrow-derived mesenchymal stem cell (BM-MSC) could enhance β-cell action in streptozotocin (STZ)-induced diabetic rats. Forty male Sprague-Dawley rats were randomly assigned to five groups: the normal control group (Normal), diabetes mellitus (DM) group, MSC-treated group (MSC), Ex4-treated group (Ex4), and MSC plus Ex4-treated group (MSC+Ex4). Body weight, blood glucose level, intraperitoneal glucose tolerance test, and in vitro glucose-stimulated insulin secretion were used to assess the treatment efficacy. The expression level of insulin, glucagon, pancreatic duodenal homeobox-1 (PDX-1), v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MafA), glucagon-like peptide-1 receptor (GLP-1R), and forkhead transcription factor 1 (FoxO1) was estimated by immunofluorescence analysis. Proliferation was assessed by Ki67 staining, and apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining in β-cells. Glucose-induced insulin secretion in the MSC+Ex4 group was significantly increased compared to that in the MSC group in vitro and in vivo. Compared to that of the other groups, the number of insulin-immunopositive cells was increased in both the MSC and MSC+Ex4 groups. However, β-cell proliferation and apoptosis in the MSC group and MSC+Ex4 group were not significantly different. Importantly, the expression level of PDX-1, MafA, FoxO1, and GLP-1R in β-cells in the MSC+Ex4 group was significantly higher than those in the MSC group. The numbers of insulin+ glucagon+ double positive cells and glucagon+ GLP-1+ double positive cells were significantly increased after MSC treatment and MSC+Ex4 combined treatment, suggesting the enhanced function of newly formed islet β-cells. Our findings showed that the combination of MSC and Ex4 enhanced the function of newly formed β-cells in STZ-induced diabetic rats by acting on multiple insulin transcription factors. Thus, combined MSC and Ex4 therapy provides a feasible approach for future diabetes treatments.

Stem cells from human exfoliated deciduous teeth ameliorate type II diabetic mellitus in Goto-Kakizaki rats

BACKGROUND

By 2030, diabetes mellitus (DM) will be the 7th leading cause of death worldwide. Type 2 DM (T2DM) is the most common type of DM and is characterized by insulin resistance and defective β-cell secretory function. Stem cells from human exfoliated deciduous teeth (SHED) are favorable seed cells for mesenchymal stem cells (MSCs)-based therapy due to their higher proliferation rates and easier access to retrieval. Currently, no study has revealed the therapeutic efficiency of MSCs for T2DM in Goto-Kakizaki (GK) rats. Hence, we aimed to explore the effect of SHED on T2DM in GK rats.

MATERIALS AND METHODS

We investigated the effects of SHED on the progression of T2DM in GK rats. SHED and bone marrow mesenchymal stem cells (BMSCs) were injected via the tail vein. Body weight, fasting blood glucose and non-fasting blood glucose were measured before and after administration. At 8 weeks after injection, intraperitoneal insulin tolerance tests (IPITTs) and insulin release tests (IRTs) were performed. Additionally, hematoxylin-eosin (HE) staining, periodic acid-Schiff (PAS) staining and double-label immunofluorescence staining were used to explore the pathological changes in pancreatic islets and the liver. Immunohistochemistry (IHC) was employed to detect SHED engraftment in the liver. Additionally, real-time PCR and western blotting were used to explore glycogen synthesis, glycolysis and gluconeogenesis in the liver.

RESULTS

At 8 weeks after SHED injection, T2DM was dramatically attenuated, including hyperglycemia, IPGTT and IRT. Additionally, histological analysis showed that SHED injection improved pancreatic islet and liver damage. Real-time PCR analysis showed that SHED significantly reversed the diabetic-induced increase of G-6-Pase, Pck1 and PK; and significantly reversed the diabetic-induced decrease of GSK3β, GLUT2, and PFKL. In addition, western blotting demonstrated that SHED significantly reversed the diabetic-induced increase of G-6-Pase and reversed the diabetic-induced decrease of GLUT2, GSK3β and PFKM.

CONCLUSION

Stem cells from human exfoliated deciduous teeth offers a potentially effective therapeutic modality for ameliorating T2DM, including hyperglycemia, insulin resistance, pancreatic islets and liver damage, and decreased glycogen synthesis, inhibited glycolysis and increased gluconeogenesis in the liver.

Bone-Marrow-Derived Mesenchymal Stromal Cells (MSC) from Diabetic and Nondiabetic Rats Have Similar Therapeutic Potentials

BACKGROUND

Diabetes mellitus is a severe chronic disease leading to systemic complications, including cardiovascular dysfunction. Previous cell therapy studies have obtained promising results with the use bone marrow mesenchymal stromal cells derived from healthy animals (MSCc) in diabetes animal models. However, the ability of MSC derived from diabetic rats to improve functional cardiac parameters is still unknown.

OBJECTIVES

To investigate whether bone-marrow-derived MSC from diabetic rats (MSCd) would contribute to recover metabolic and cardiac electrical properties in other diabetic rats.

METHODS

Diabetes was induced in Wistar rats with streptozotocin. MSCs were characterized by flow cytometry, morphological analysis, and immunohistochemistry. Cardiac electrical function was analyzed using recordings of ventricular action potential. Differences between variables were considered significant when p < 0.05.

RESULTS

In vitro properties of MSCc and MSCd were evaluated. Both cell types presented similar morphology, growth kinetics, and mesenchymal profile, and could differentiate into adipogenic and osteogenic lineages. However, in an assay for fibroblast colony-forming units (CFU-F), MSCd formed more colonies than MSCc when cultured in expansion medium with or without hydrocortisone (1 µM). In order to compare the therapeutic potential of the cells, the animals were divided into four experimental groups: nondiabetic (CTRL), diabetic (DM), diabetic treated with MSCc (DM + MSCc), and diabetic treated with MSCd (DM + MSCd). The treated groups received a single injection of MSC 4 weeks after the development of diabetes. MSCc and MSCd controlled hyperglycemia and body weight loss and improved cardiac electrical remodeling in diabetic rats.

CONCLUSIONS

MSCd and MSCc have similar in vitro properties and therapeutic potential in a rat model of diabetes induced with streptozotocin.

Omental adipose tissue is a more suitable source of canine Mesenchymal stem cells

Background

Mesenchymal Stem Cells (MSCs) are a promising therapeutic tool in veterinary medicine. Currently the subcutaneous adipose tissue is the leading source of MSCs in dogs. MSCs derived from distinct fat depots have shown dissimilarities in their accessibility and therapeutic potential. The aims of our work were to determine the suitability of omental adipose tissue as a source of MSCs, according to sampling success, cell yield and paracrine properties of isolated cells, and compared to subcutaneous adipose tissue.

Results

While sampling success of omental adipose tissue was 100% (14 collections from14 donors) for subcutaneous adipose tissue it was 71% (10 collections from 14 donors). MSCs could be isolated from both sources. Cell yield was significantly higher for omental than for subcutaneous adipose tissue (38 ± 1 vs. 30 ± 1 CFU-F/g tissue, p < 0.0001). No differences were observed between sources regarding cell proliferation potential (73 ± 1 vs. 74 ± 1 CDPL) and cell senescence (at passage 10, both cultures presented enlarged cells with cytoplasmic vacuoles and cellular debris). Omental- and subcutaneous-derived MSCs expressed at the same level bFGF, PDGF, HGF, VEGF, ANG1 and IL-10. Irrespective of the source, isolated MSCs induced proliferation, migration and vascularization of target cells, and inhibited the activation of T lymphocytes.

Conclusion

Compared to subcutaneous adipose tissue, omental adipose tissue is a more suitable source of MSCs in dogs. Since it can be procured from donors with any body condition, its collection procedure is always feasible, its cell yield is high and the MSCs isolated from it have desirable differentiation and paracrine potentials.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-1053-0) contains supplementary material, which is available to authorized users.

Recipient Glycemic Micro-environments Govern Therapeutic Effects of Mesenchymal Stem Cell Infusion on Osteopenia

Therapeutic effects of mesenchymal stem cell (MSC) infusion have been revealed in various human disorders, but impacts of diseased micro-environments are only beginning to be noticed. Donor diabetic hyperglycemia is reported to impair therapeutic efficacy of stem cells. However, whether recipient diabetic condition also affects MSC-mediated therapy is unknown. We and others have previously shown that MSC infusion could cure osteopenia, particularly in ovariectomized (OVX) mice. Here, we discovered impaired MSC therapeutic effects on osteopenia in recipient type 1 diabetes (T1D). Through intensive glycemic control by daily insulin treatments, therapeutic effects of MSCs on osteopenia were maintained. Interestingly, by only transiently restoration of recipient euglycemia using single insulin injection, MSC infusion could also rescue T1D-induced osteopenia. Conversely, under recipient hyperglycemia induced by glucose injection in OVX mice, MSC-mediated therapeutic effects on osteopenia were diminished. Mechanistically, recipient hyperglycemic micro-environments reduce anti-inflammatory capacity of MSCs in osteoporotic therapy through suppressing MSC interaction with T cells via the Adenosine monophosphate-activated protein kinase (AMPK) pathway. We further revealed in diabetic micro-environments, double infusion of MSCs ameliorated osteopenia by anti-inflammation, attributed to the first transplanted MSCs which normalized the recipient glucose homeostasis. Collectively, our findings uncover a previously unrecognized role of recipient glycemic conditions controlling MSC-mediated therapy, and unravel that fulfillment of potent therapeutic effects of MSCs requires tight control of recipient micro-environments.

Administration of multipotent mesenchymal stromal cells restores liver regeneration and improves liver function in obese mice with hepatic steatosis after partial hepatectomy

Background

The liver has the remarkable capacity to regenerate in order to compensate for lost or damaged hepatic tissue. However, pre-existing pathological abnormalities, such as hepatic steatosis (HS), inhibits the endogenous regenerative process, becoming an obstacle for liver surgery and living donor transplantation.

Recent evidence indicates that multipotent mesenchymal stromal cells (MSCs) administration can improve hepatic function and increase the potential for liver regeneration in patients with liver damage. Since HS is the most common form of chronic hepatic illness, in this study we evaluated the role of MSCs in liver regeneration in an animal model of severe HS with impaired liver regeneration.

Methods

C57BL/6 mice were fed with a regular diet (normal mice) or with a high-fat diet (obese mice) to induce HS. After 30 weeks of diet exposure, 70% hepatectomy (Hpx) was performed and normal and obese mice were divided into two groups that received 5 × 10⁵ MSCs or vehicle via the tail vein immediately after Hpx.

Results

We confirmed a significant inhibition of hepatic regeneration when liver steatosis was present, while the hepatic regenerative response was promoted by infusion of MSCs. Specifically, MSC administration improved the hepatocyte proliferative response, PCNA-labeling index, DNA synthesis, liver function, and also reduced the number of apoptotic hepatocytes.

These effects may be associated to the paracrine secretion of trophic factors by MSCs and the hepatic upregulation of key cytokines and growth factors relevant for cell proliferation, which ultimately improves the survival rate of the mice.

Conclusions

MSCs represent a promising therapeutic strategy to improve liver regeneration in patients with HS as well as for increasing the number of donor organs available for transplantation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0469-y) contains supplementary material, which is available to authorized users.

Infusion with Human Bone Marrow-derived Mesenchymal Stem Cells Improves β-cell Function in Patients and Non-obese Mice with Severe Diabetes

Mesenchymal stem cells (MSCs) transplantation is a promising therapeutic strategy for type 1 diabetes (T1D). However, little is known on whether MSC transplantation can benefit T1D patients with ketoacidosis and its potential actions. Here, we show that infusion with bone marrow MSCs preserves β-cell function in some T1D patients with ketoacidosis by decreasing exogenous insulin requirement and increasing plasma C-peptide levels up to 1–2 years. MSC transplantation increased plasma and islet insulin contents in non-obese diabetic (NOD) mice with severe diabetes. In comparison with severe diabetes controls, MSC infusion reduced insulitis, decreased pancreatic TNF-α, and increased IL-10 and TGF-β1 expression in NOD mice. MSC infusion increased the percentages of splenic Tregs and levels of plasma IL-4, IL-10 and TGF-β1, but reduced the percentages of splenic CD8⁺ T and levels of plasma IFN-γ, TNF-α and IL-17A in NOD mice. Finally, infused MSCs predominantly accumulated in pancreatic tissues at 28 days post infusion. The effects of MSCs on preserving β-cell function and modulating inflammation tended to be dose-dependent and multiple doses of MSCs held longer effects in NOD mice. Hence, MSC transplantation preserved β-cell function in T1D patients and NOD mice with severe diabetes by enhancing Treg responses.

Long term effect and safety of Wharton's jelly-derived mesenchymal stem cells on type 2 diabetes

Cellular therapies offer novel opportunities for the treatment of type 2 diabetes mellitus (T2DM). The present study evaluated the long-term efficacy and safety of infusion of Wharton's jelly-derived mesenchymal stem cells (WJ-MSC) on T2DM. A total of 61 patients with T2DM were randomly divided into two groups on the basis of basal therapy; patients in group I were administered WJ-MSC intravenous infusion twice, with a four-week interval, and patients in group II were treated with normal saline as control. During the 36-month follow-up period, the occurrence of any adverse effects and the results of clinical and laboratory examinations were recorded and evaluated. The lack of acute or chronic adverse effects in group I was consistent with group II.. Blood glucose, glycosylated hemoglobin, C-peptide, homeostasis model assessment of pancreatic islet β-cell function and incidence of diabetic complications in group I were significantly improved, as compared with group II during the 36-month follow-up. The results of the present study demonstrated that infusion of WJ-MSC improved the function of islet β-cells and reduced the incidence of diabetic complications, although the precise mechanisms are yet to be elucidated. The infusion of WJ-MSC may be an effective option for the treatment of patients with type 2 diabetes.

Metabolic and pancreatic effects of bone marrow mesenchymal stem cells transplantation in mice fed high-fat diet

The purpose of this study was to investigate the effects of multiple infusions of allogeneic MSCs on glucose homeostasis and morphometry of pancreatic islets in high- fat diet (HFD) fed mice. Swiss mice were fed standard diet (C group) or HFD (HFD group). After 8 weeks, animals of HFD group received sterile phosphate-buffered saline infusions (HFD-PBS) or four infusions of MSCs one week apart (HFD-MSCs). Fasting glycemia (FG) was determined weekly and glucose (GTT) and insulin (ITT) tolerance tests were performed 4, 8, 12, and 16 weeks after the infusions of MSCs. The MSCs transplanted mice were classified as responder (FG < 180 mg/dL, 72.2% of transplanted mice) or non-responder (FG > 180mg/dL, 28.8%) Seven weeks after MSCs infusions, FG decreased in HFD-MSCs responder mice compared with the HFD-PBS group. Sixteen weeks post MSCs infusions, GTT and ITT areas under the curve (AUC) decreased in HFD-MSCs responder mice compared to HFD-PBS group. Serum insulin concentration was higher in HFD-PBS group than in control animals and was not different compared with the other groups. The relative volume of α-cells was significantly smaller in HFD-PBS group than in C group and significantly higher in HFD-MSCs-NR than in HFD-PBS and HFD-MSCs-R groups. Cell apoptosis in the islets was higher in HFD-PBS group than in C group, and lower in HFD-MSCs responder mice than in HFD-PBS group and non-responder animals. The results demonstrate the ability of multiple infusions of MSCs to promote prolonged decrease in hyperglycemia and apoptosis in pancreatic islets and increase in insulin sensitivity in HFD fed mice.

Could cancer and infection be adverse effects of mesenchymal stromal cell therapy?

Multipotent mesenchymal stromal cells [also referred to as mesenchymal stem cells (MSCs)] are a heterogeneous subset of stromal cells. They can be isolated from bone marrow and many other types of tissue. MSCs are currently being tested for therapeutic purposes (i.e., improving hematopoietic stem cell engraftment, managing inflammatory diseases and regenerating damaged organs). Their tropism for tumors and inflamed sites and their context-dependent potential for producing trophic and immunomodulatory factors raises the question as to whether MSCs promote cancer and/or infection. This article reviews the effect of MSCs on tumor establishment, growth and metastasis and also susceptibility to infection and its progression. Data published to date shows a paradoxical effect regarding MSCs, which seems to depend on isolation and expansion, cells source and dose and the route and timing of administration. Cancer and infection may thus be adverse or therapeutic effects arising form MSC administration.

Generation of insulin-producing cells from C3H10T1/2 mesenchymal progenitor cells

Mesenchymal stem cells (MSCs) have been reported to be an attractive source for the generation of transplantable surrogate β cells. A murine embryonic mesenchymal progenitor cell line C3H10T1/2 has been recognized as a model for MSCs, because of its multi-lineage differentiation potential. The purpose of this study was to explore whether C3H/10T1/2 cells have the potential to differentiate into insulin-producing cells (IPCs). Here, we investigated and compared the in vitro differentiation of rat MSCs and C3H10T1/2 cells into IPCs. After the cells underwent IPC differentiation, the expression of differentiation markers were detected by immunocytochemistry, reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time RT-PCR (qRT-PCR) and Western blotting. The insulin secretion was evaluated by enzyme-linked immunosorbent assay (ELISA). Furthermore, these differentiated cells were transplanted into streptozotocin-induced diabetic mice and their biological functions were tested in vivo. This study reports a 2-stage method to generate IPCs from C3H10T1/2 cells. Under specific induction conditions for 7-8 days, C3H10T1/2 cells formed three-dimensional spheroid bodies (SBs) and secreted insulin, while generation of IPCs derived from rat MSCs required a long time (more than 2 weeks). Furthermore, these IPCs derived from C3H10T1/2 cells were injected into diabetic mice and improves basal glucose, body weight and exhibited normal glucose tolerance test. The present study provided a simple and faithful in vitro model for further investigating the mechanism underlying IPC differentiation of MSCs and cell replacement therapy for diabetes.

Effect of combined therapy of human Wharton's jelly-derived mesenchymal stem cells from umbilical cord with sitagliptin in type 2 diabetic rats

Type 2 diabetes mellitus is the most common endocrine disease all over the world, while existing therapies can only ameliorate hyperglycemia or temporarily improve the response to insulin in target tissues, they cannot retard or improve the progressive β-cell dysfunction persistently. Combined therapy of stem cells and sitagliptin might resolve this problem, we verified this hypothesis in a diabetic rat model. Except ten Wistar rats in normal control group, diabetic rats were divided into diabetic control group, WJ-MSCs group, sitagliptin group and WJ-MSCs + sitagliptin group and received homologous therapy. Ten weeks after therapy, diabetic symptoms, FPG and GHbA1c in WJ-MSCs group, sitagliptin group and WJ-MSCs + sitagliptin group were significantly less than those in diabetic control group (P < 0.05), while fasting C-peptide and number of β cells in WJ-MSCs group and WJ-MSCs + sitagliptin group was significantly higher than those in diabetic control and sitagliptin group (P < 0.01). Glucagon and number of α cells in sitagliptin group and WJ-MSCs + sitagliptin group were significantly lower than those in WJ-MSCs group and diabetic control group (P < 0.01). No symptoms of rejection and toxic effect were observed. Combined therapy of WJ-MSCs and sitagliptin can effectively ameliorate hyperglycemia, promote regeneration of islet β cells and suppress generation of islet α cells in diabetic rats, presenting a new therapy for type 2 diabetes although the exact mechanisms are unclear.

The antidiabetic effect of mesenchymal stem cells is unrelated to their transdifferentiation potential but to their capability to restore Th1/Th2 balance and to modify the pancreatic microenvironment

Type 1 diabetes mellitus (T1DM) is a chronic metabolic disease that results from cell-mediated autoimmune destruction of insulin-producing cells. In T1DM animal models, it has been shown that the systemic administration of multipotent mesenchymal stromal cells, also referred as to mesenchymal stem cells (MSCs), results in the regeneration of pancreatic islets. Mechanisms underlying this effect are still poorly understood. Our aims were to assess whether donor MSCs (a) differentiate into pancreatic β-cells and (b) modify systemic and pancreatic pathophysiologic markers of T1DM. After the intravenous administration of 5 × 10(5) syngeneic MSCs, we observed that mice with T1DM reverted their hyperglycemia and presented no donor-derived insulin-producing cells. In contrast, 7 and 65 days post-transplantation, MSCs were engrafted into secondary lymphoid organs. This correlated with a systemic and local reduction in the abundance of autoaggressive T cells together with an increase in regulatory T cells. Additionally, in the pancreas of mice with T1DM treated with MSCs, we observed a cytokine profile shift from proinflammatory to antinflammatory. MSC transplantation did not reduce pancreatic cell apoptosis but recovered local expression and increased the circulating levels of epidermal growth factor, a pancreatic trophic factor. Therefore, the antidiabetic effect of MSCs intravenously administered is unrelated to their transdifferentiation potential but to their capability to restore the balance between Th1 and Th2 immunological responses along with the modification of the pancreatic microenvironment. Our data should be taken into account when designing clinical trials aimed to evaluate MSC transplantation in patients with T1DM since the presence of endogenous precursors seems to be critical in order to restore glycemic control.

Bone marrow stem cell as a potential treatment for diabetes

Diabetes mellitus (DM) is a group of metabolic diseases in which a person has high blood glucose levels resulting from defects in insulin secretion and insulin action. The chronic hyperglycemia damages the eyes, kidneys, nerves, heart, and blood vessels. Curative therapies mainly include diet, insulin, and oral hypoglycemic agents. However, these therapies fail to maintain blood glucose levels in the normal range all the time. Although pancreas or islet-cell transplantation achieves better glucose control, a major obstacle is the shortage of donor organs. Recently, research has focused on stem cells which can be classified into embryonic stem cells (ESCs) and tissue stem cells (TSCs) to generate functional β cells. TSCs include the bone-marrow-, liver-, and pancreas-derived stem cells. In this review, we focus on treatment using bone marrow stem cells for type 1 and 2 DM.

β-Cell regeneration mediated by human bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs) have been shown to ameliorate diabetes in animal models. The mechanism, however, remains largely unknown. An unanswered question is whether BMSCs are able to differentiate into β-cells in vivo, or whether BMSCs are able to mediate recovery and/or regeneration of endogenous β-cells. Here we examined these questions by testing the ability of hBMSCs genetically modified to transiently express vascular endothelial growth factor (VEGF) or pancreatic-duodenal homeobox 1 (PDX1) to reverse diabetes and whether these cells were differentiated into β-cells or mediated recovery through alternative mechanisms. Human BMSCs expressing VEGF and PDX1 reversed hyperglycemia in more than half of the diabetic mice and induced overall improved survival and weight maintenance in all mice. Recovery was sustained only in the mice treated with hBMSCs-VEGF. However, de novo β-cell differentiation from human cells was observed in mice in both cases, treated with either hBMSCs-VEGF or hBMSCs- PDX1, confirmed by detectable level of serum human insulin. Sustained reversion of diabetes mediated by hBMSCs-VEGF was secondary to endogenous β-cell regeneration and correlated with activation of the insulin/IGF receptor signaling pathway involved in maintaining β-cell mass and function. Our study demonstrated the possible benefit of hBMSCs for the treatment of insulin-dependent diabetes and gives new insight into the mechanism of β-cell recovery after injury mediated by hBMSC therapy.

Infusion of mesenchymal stem cells ameliorates hyperglycemia in type 2 diabetic rats: identification of a novel role in improving insulin sensitivity

Infusion of mesenchymal stem cells (MSCs) has been shown to effectively lower blood glucose in diabetic individuals, but the mechanism involved could not be adequately explained by their potential role in promoting islet regeneration. We therefore hypothesized that infused MSCs might also contribute to amelioration of the insulin resistance of peripheral insulin target tissues. To test the hypothesis, we induced a diabetic rat model by high-fat diet/streptozotocin (STZ) administration, performed MSC infusion during the early phase (7 days) or late phase (21 days) after STZ injection, and then evaluated the therapeutic effects of MSC infusion and explored the possible mechanisms involved. MSC infusion ameliorated hyperglycemia in rats with type 2 diabetes (T2D). Infusion of MSCs during the early phase not only promoted β-cell function but also ameliorated insulin resistance, whereas infusion in the late phase merely ameliorated insulin resistance. Infusion of MSCs resulted in an increase of GLUT4 expression and an elevation of phosphorylated insulin receptor substrate 1 (IRS-1) and Akt (protein kinase B) in insulin target tissues. This is the first report of MSC treatment improving insulin sensitivity in T2D. These data indicate that multiple roles and mechanisms are involved in the efficacy of MSCs in ameliorating hyperglycemia in T2D.

Concise review: pancreas regeneration: recent advances and perspectives

The replacement of functional pancreatic β-cells is seen as an attractive potential therapy for diabetes, because diabetes results from an inadequate β-cell mass. Inducing replication of the remaining β-cells and new islet formation from progenitors within the pancreas (neogenesis) are the most direct ways to increase the β-cell mass. Stimulation of both replication and neogenesis have been reported in rodents, but their clinical significance must still be shown. Because human islet transplantation is limited by the scarcity of donors and graft failure within a few years, efforts have recently concentrated on the use of stem cells to replace the deficient β-cells. Currently, embryonic stem cells and induced pluripotent stem cells achieve high levels of β-cell differentiation, but their clinical use is still hampered by ethical issues and/or the risk of developing tumors after transplantation. Pancreatic epithelial cells (duct, acinar, or α-cells) represent an appealing alternative to stem cells because they demonstrate β-cell differentiation capacities. Yet translation of such capacity to human cells after significant in vitro expansion has yet to be achieved. Besides providing new β-cells, cell therapy also has to address the question on how to protect the transplanted cells from destruction by the immune system via either allo- or autoimmunity. Encouraging developments have been made in encapsulation and immunomodulation techniques, but many challenges still remain. Herein, we discuss recent advances in the search for β-cell replacement therapies, current strategies for circumventing the immune system, and mandatory steps for new techniques to be translated from bench to clinics.