Differentiation of human adipose-derived mesenchymal stem cell into insulin-producing cells: an in vitro study

Stem cells with the ability to differentiate into insulin-producing cells (IPCs) are becoming the most promising therapy for diabetes mellitus and reduce the major limitations of availability and allogeneic rejection of beta cell transplantations. Mesenchymal stem cells (MSCs) are pluripotent stromal cells with the ability to proliferate and differentiate into a variety of cell types including endocrine cells of the pancreas. This study sought to inspect the in vitro differentiation of human adipose-derived tissue stem cells into IPCs which could provide an abundant source of cells for the purpose of diabetic cell therapy in addition to avoid immunological rejection. Adipose-derived MSCs were obtained from liposuction aspirates and induced to differentiate into insulin-secreting cells under a three-stage protocol based on a combination of low-glucose DMEM medium, β-mercaptoethanol, and nicotinamide for pre-induction and high-glucose DMEM, β-mercaptoethanol, nicotinamide, and exendin-4 for induction stages of differentiation. Differentiation was evaluated by the analysis of morphology, dithizone staining, RT-PCR, and immunocytochemistry. Morphological changes including typical islet-like cell clusters were observed by phase-contrast microscope at the end of differentiation protocol. Based on dithizone staining, differentiated cells were positive and undifferentiated cells were not stained. Furthermore, RT-PCR results confirmed the expression of insulin, PDX1, Ngn3, PAX4, and GLUT2 in differentiated cells. Moreover, insulin production by the IPCs was confirmed by immunocytochemistry analysis. It is concluded that adipose-derived MSCs could differentiate into insulin-producing cells in vitro.     

Insulin-producing cells from human pancreatic islet-derived progenitor cells following transplantation in mice

Stem/progenitor cells hold promise for alleviating/curing type 1 diabetes due to the capacity to differentiate into functional insulin-producing cells. The current study aims to assess the differentiation potential of human pancreatic IPCs (islet-derived progenitor cells). IPCs were derived from four human donors and subjected to more than 2000-fold expansion before turning into ICCs (islet-like cell clusters). The ICCs expressed ISL-1 Glut2, PDX-1, ngn3, insulin, glucagon and somatostatin at the mRNA level and stained positive for insulin and glucagon by immunofluorescence. Following glucose challenge in vitro, C-peptide was detected in the sonicated ICCs, instead of in the conditioned medium. To examine the function of the cells in vivo, IPCs or ICCs were transplanted under the renal capsule of immunodeficient mice. One month later, 19 of 28 mice transplanted with ICCs and 4 of 14 mice with IPCs produced human C-peptide detectable in blood, indicating that the in vivo environment further facilitated the maturation of ICCs. However, among the hormone-positive mice, only 9 of 19 mice with ICCs and two of four mice with IPCs were able to secrete C-peptide in response to glucose.     

Generation of insulin-producing cells from gnotobiotic porcine skin-derived stem cells

A major problem in the treatment of type 1 diabetes mellitus is the limited availability of alternative sources of insulin-producing cells for islet transplantation. In this study, we investigated the effect of bone morphogenetic protein 4 (BMP-4) treatments of gnotobiotic porcine skin-derived stem cells (gSDSCs) on their reprogramming and subsequent differentiation into insulin-producing cells (IPCs). We isolated SDSCs from the ear skin of a gnotobiotic pig. During the proliferation period, the cells expressed stem-cell markers Oct-4, Sox-2, and CD90; nestin expression also increased significantly. The cells could differentiate into IPCs after treatments with activin-A, glucagon-like peptide-1 (GLP-1), and nicotinamide. After 15 days in the differentiation medium, controlled gSDSCs began expressing endocrine progenitor genes and proteins (Ngn3, Neuro-D, PDX-1, NKX2.2, NKX6.1, and insulin). The IPCs showed increased insulin synthesis after glucose stimulation. The results indicate that stem cells derived from the skin of gnotobiotic pigs can differentiate into IPCs under the appropriate conditions in vitro. Our three-stage induction protocol could be applied without genetic modification to source IPCs from stem cells in the skin of patients with diabetes for autologous transplantation.     

Differential effect of activin on mouse embryonic stem cell differentiation in insulin-secreting cells under nestin-positive selection and spontaneous differentiation protocols

Parallel to the importance of the development of cell therapies to treat diabetes is the production of sufficient numbers of pancreatic endocrine cells that function like primary islets. To increase the efficiency of endocrine pancreatic-like cell differentiation from mouse embryonic stem cells (ESCs), we applied activin-B to nestin-positive selection (protocol 1) and spontaneous differentiation (protocol 2) in different groups including: [A] activin-B, or [B] basic fibroblast growth factor (bFGF), and/or [C] activin-B+bFGF. The differentiated cells expressed most pancreatic-related genes. The number of insulin- and C peptide-positive cells, as well as dithizone-positive clusters in group A of protocol 1 was higher than in the other groups. Significant insulin concentrations in protocol 1 were produced when glucose was added to the medium, in comparison with protocol 2. Moreover, insulin release was increased significantly in group A of protocol 1 even with lower glucose. In conclusion, Addition of activin-B in a nestin-positive selection protocol increased the insulin-secreting cells in comparison with the same protocol with bFGF and/or spontaneous differentiation in presence of bFGF and/or activin-B alone. However, improvements of the current method are required to generate a sufficient source of true beta-cells for the treatment of diabetes mellitus.     

Induction of insulin‐producing cells from umbilical cord blood‐derived stromal cells by activation of the c‐Met/HGF axis

Efficient and effective therapies are required for diabetes mellitus. The use of adult stem cells for treating diabetes represents a major focus of current research. We have attempted to differentiate adult stem cells produced from umbilical cord blood‐derived stromal cells into insulin‐producing cells (IPCs). By activating the c‐Met/HGF axis through temporal hypoxia treatment and hepatocyte growth factor (HGF) supplementation, our protocol resulted in the differentiation of cells into functional pancreatic endocrine cells with increased viability. Glucose stimulation test results showed that significantly greater amounts of C‐peptide and insulin were released from the differentiated cells than from undifferentiated cells. These IPCs were capable of reversing the hyperglycemia of diabetic mice. In conclusion, targeting the c‐Met/HGF axis can be considered an effective and efficient means of obtaining IPCs from adult stem cells.     

Research status and prospect of stem cells in the treatment of diabetes mellitus

Beta cell mass and function are decreased to varying degrees in diabetes. Islet cell replacement or regenerative therapy may offer great therapeutic promise to people with diabetes. In addition to primary pancreatic β cells, recent studies on regeneration of functional insulin producing cells (IPCs) revealed that several alternative cell sources, including embryonic stem cells, induced pluripotent stem cells and adult stem cells, can generate IPCs by differentiation, reprogramming, and trans-differentiation. In this review, we discuss stem cells as a potential alternative cell source for the treatment of diabetes.     

Insulin-Producing Cells Derived from Human Embryonic Stem Cells: Comparison of Definitive Endoderm- and Nestin-Positive Progenitor-Based Differentiation Strategies

Human embryonic stem cells (hESCs) are pluripotent and capable of undergoing multilineage differentiation into highly specialized cells including pancreatic islet cells. Thus, they represent a novel alternative source for targeted therapies and regenerative medicine for diabetes. Significant progress has been made in differentiating hESCs toward pancreatic lineages. One approach is based on the similarities of pancreatic β cell and neuroepithelial development. Nestin-positive cells are selected as pancreatic β cell precursors and further differentiated to secrete insulin. The other approach is based on our knowledge of developmental biology in which the differentiation protocol sequentially reproduces the individual steps that are known in normal β cell ontogenesis during fetal pancreatic development. In the present study, the hESC cell line PKU1.1 was induced to differentiate into insulin-producing cells (IPCs) using both protocols. The differentiation process was dynamically investigated and the similarities and differences between both strategies were explored. Our results show that IPCs can be successfully induced with both differentiation strategies. The resulting IPCs from both protocols shared many similar features with pancreatic islet cells, but not mature, functional β cells. However, these differently-derived IPC cell types displayed specific morphologies and different expression levels of pancreatic islet development-related markers. These data not only broaden our outlook on hESC differentiation into IPCs, but also extend the full potential of these processes for regenerative medicine in diabetes.     

Human bone marrow mesenchymal stem cells differentiate into insulin-producing cells upon microenvironmental manipulation in vitro

It was recently reported that pluripotent mesenchymal stem cells (MSCs) in rodent bone marrow (BM) have the capacity to generate insulin-producing cells (IPCs) in vitro. However, little is known about this capacity in human BM-MSCs. We developed a nongenetic method to induce human BM-MSCs to transdifferentiate into IPCs both phenotypically and functionally. BM-MSCs from 12 human donors were sequentially cultured in specially defined conditions. Their differentiation extent toward β-cell phenotype was evaluated systemically. Specifically, after induction human BM-MSCs formed spheroid islet-like clusters containing IPCs, which was further confirmed by dithizone (DTZ) staining and electron microscopy. These IPCs expressed multiple genes related to the development or function of pancreatic β cells (including NKX6.1, ISL-1, Beta2/Neurod, Glut2, Pax6, nestin, PDX-1, ngn3, insulin and glucagon). The coexpression of insulin and c-peptide was observed in IPCs by immunofluorescence. Moreover, they were able to release insulin in a glucose-dependent manner and ameliorate the diabetic conditions of streptozotocin (STZ)-treated nude mice. These results indicate that human BM-MSCs might be an available candidate to overcome limitations of islet transplantation.     

A feasibility study of an in vitro differentiation potential toward insulin-producing cells by dental tissue-derived mesenchymal stem cells

Dental tissue-derived mesenchymal stem cells have been proposed as an alternative source for mesenchymal stem cells. Here, we investigated the differentiation ability toward insulin producing cells (IPCs) of human dental pulp stem cells (hDPSCs) and human periodontal ligament stem cells (hPDLSCs). These cells expressed mesenchymal stem cell surface markers and were able to differentiate toward osteogenic and adipogenic lineages. Upon 3 step-IPCs induction, hDPSCs exhibited more colony number than hPDLSCs. The mRNA upregulation of pancreatic endoderm/islet markers was noted. However, the significant increase was noted only for PDX-1, NGN-3, and INSULIN mRNA expression of hDPSCs. The hDPSCs-derived IPCs expressed PRO-INSULIN and released C-PEPTIDE upon glucose stimulation in dose-dependent manner. After IPCs induction, the Notch target, HES-1 and HEY-1, mRNA expression was markedly noted. Notch inhibition during the last induction step or throughout the protocol disturbed the ability of C-PEPTIDE release upon glucose stimulation. The results suggested that hDPSCs had better differentiation potential toward IPCs than hPDLSCs. In addition, the Notch signalling might involve in the differentiation regulation of hDPSCs into IPCs.     

Three-dimensional differentiation of adipose-derived mesenchymal stem cells into insulin-producing cells

The aim of this study is to evaluate the collagen/hyaluronic acid (Col/HA) scaffold effect on the differentiation of insulin-producing cells (IPCs) from adipose-derived mesenchymal stem cells (ASCs). In this experimental study, ASCs were cultured and seeded in a Col/HA scaffold (3D culture) and then treated with induction media. After induction, the presence of IPCs was evaluated using gene expression (PDX-1, GLUT-2 and insulin) analysis and immunocytochemistry, while functional maturity was determined by measuring insulin release in response to low- and high-glucose media. The induced IPCs were morphologically similar to pancreatic islet-like cells. Expression of the islet-associated genes PDX-1, GLUT-2 and insulin genes in 3D-cultured cells was markedly higher than the 2D-cultured cells exposure differentiation media. Compared to the 2D culture of ASCs-derived IPCs, the insulin release from 3D ASCs-derived IPCs showed a nearly 4-fold (p?<?0.05) increase when exposed to a high glucose (25 mmol) medium. The percentage of insulin-positive cells in the 3D experimental group showed an approximately 4-fold increase compared to the 2D experimental culture cells. The results of this study demonstrated that the COL/HA scaffold can enhance the differentiation of IPCs from rat ASCs.     

FoxO1 inhibition promotes differentiation of human embryonic stem cells into insulin producing cells

Insulin-producing cells (IPCs) derived from human embryonic stem cells (hESCs) hold great potential for cell transplantation therapy in diabetes. Tremendous progress has been made in inducing differentiation of hESCs into IPCs in vitro, of which definitive endoderm (DE) protocol mimicking foetal pancreatic development has been widely used. However, immaturity of the obtained IPCs limits their further applications in treating diabetes. Forkhead box O1 (FoxO1) is involved in the differentiation and functional maintenance of murine pancreatic β cells, but its role in human β cell differentiation is under elucidation. Here, we showed that although FoxO1 expression level remained consistent, cytoplasmic phosphorylated FoxO1 protein level increased during IPC differentiation of hESCs induced by DE protocol. Lentiviral silencing of FoxO1 in pancreatic progenitors upregulated the levels of pancreatic islet differentiation-related genes and improved glucose-stimulated insulin secretion response in their progeny IPCs, whereas overexpression of FoxO1 showed the opposite effects. Notably, treatment with the FoxO1 inhibitor AS1842856 displayed similar effects with FoxO1 knockdown in pancreatic progenitors. These effects were closely associated with the mutually exclusive nucleocytoplasmic shuttling of FoxO1 and Pdx1 in the AS1842856-treated pancreatic progenitors. Our data demonstrated a promising effect of FoxO1 inhibition by the small molecule on gene expression profile during the differentiation, and in turn, on determining IPC maturation via modulating subcellular location of FoxO1 and Pdx1. Therefore, we identify a novel role of FoxO1 inhibition in promoting IPC differentiation of hESCs, which may provide clues for induction of mature β cells from hESCs and clinical applications in regenerative medicine.     

Differentiation of mesenchymal stem cells to insulin-producing cells and their impact on type 1 diabetic rats

Cell therapy is thought to be a possible approach for treatment of diabetes. Cells with the ability to differentiate into insulin-producing cells (IPCs) would provide an unlimited source of islet cells for transplantation. In this study, the differentiation capacity of rat bone-marrow-derived mesenchymal stem cells (MSCs) to IPCs and the feasibility of using them for reversal of hyperglycemia were investigated. In vitro studies indicated that treatment of cells with high glucose concentration, nicotinamide and β-mercaptoethanol resulted to differentiated cells, which had characteristics of IPCs including spherical, grape-like morphology, secretion of insulin, and being positive for dithizone. To test the in vivo function of differentiated MSCs, they were injected into the spleen of diabetic rats. It was shown that diabetic rats who received IPCs, significantly reduced the glucose level, in response to intraperitoneal glucose tolerance (IPGT) test. These results indicate that MSCs are capable of in vitro differentiation into functional IPCs, which can reverse hyperglycemia in rat model of diabetes.     

Pancreatic islet-like clusters from periosteum-derived progenitor cells

Recent studies comparing the insulin-producing cell (IPC) differentiation capacity of mesenchymal stem cells (MSCs) derived from four different sources (bone marrow, Wharton’s jelly, adipose tissue, and the periosteum) demonstrated that IPC differentiation of periosteum-derived progenitor cells (PDPCs) progressed faster than any other MSCs within 7 days, indicating that PDPCsare most suited to IPC differentiation. Here, two different cell culture methods, adhesion and cluster culture, were assessed for their ability to support in vitro IPC differentiation. The induction of IPC differentiation was confirmed by RTqPCR analysis of insulin gene expression levels and immunofluorescence analysis of insulin protein. An enzyme-linked immunosorbent assay was used to quantify secreted insulin. PDPC-derived IPCs from cluster cultures demonstrated a significantly increased expression of insulin and an enhanced secretion of insulin of insulin protein in response to glucose compared to IPCs derived from adhesion cultures. Thus, pancreatic islet-like cluster cultures appear to provide the optimal conditions such as cluster culture for IPC differentiation of PDPCs.     

Improved differentiation of umbilical cord blood-derived mesenchymal stem cells into insulin-producing cells by PDX-1 mRNA transfection

Numerous studies have sought to identify diabetes mellitus treatment strategies with fewer side effects. Mesenchymal stem cell (MSC) therapy was previously considered as a promising therapy; however, it requires the cells to be trans-differentiated into cells of the pancreatic-endocrine lineage before transplantation. Previous studies have shown that PDX-1 expression can facilitate MSC differentiation into insulin-producing cells (IPCs), but the methods employed to date use viral or DNA-based tools to express PDX-1, with the associated risks of insertional mutation and immunogenicity. Thus, this study aimed to establish a new method to induce PDX-1 expression in MSCs by mRNA transfection. MSCs were isolated from human umbilical cord blood and expanded in vitro, with stemness confirmed by surface markers and multipotentiality. MSCs were transfected with PDX-1 mRNA by nucleofection and chemically induced to differentiate into IPCs (combinatorial group). This IPC differentiation was then compared with that of untransfected chemically induced cells (inducer group) and uninduced cells (control group). We found that PDX-1 mRNA transfection significantly improved the differentiation of MSCs into IPCs, with 8.3±2.5% IPCs in the combinatorial group, 3.21±2.11% in the inducer group and 0% in the control. Cells in the combinatorial group also strongly expressed several genes related to beta cells (Pdx-1, Ngn3, Nkx6.1 and insulin) and could produce C-peptide in the cytoplasm and insulin in the supernatant, which was dependent on the extracellular glucose concentration. These results indicate that PDX-1 mRNA may offer a promising approach to produce safe IPCs for clinical diabetes mellitus treatment.     

Induction of human umbilical cord blood-derived stem cells with embryonic stem cell phenotypes into insulin producing islet-like structure

Success in islet-transplantation-based therapies for type I diabetes, coupled with a worldwide shortage of transplant-ready islets, has motivated efforts to develop renewable sources of islet-replacement tissue. Embryonic stem cells (ESCs) have been successfully induced into insulin producing islet-like structure in several studies. However, the source of the ESCs has presented ethical and technical concerns. Here, we isolated a population of stem cells from human cord blood (UCB), which expressed embryo stage specific maker, SSEA-4, and the multi-potential stem cell marker, Oct4. Subsequently, we successfully induced them into insulin-producing islet-like structures, which co-express insulin and C-peptide. These findings might have a significant potential to advance human UCB derived stem-cell-based therapeutics for diabetes.     

Pancreatic Insulin-Producing Cells Differentiated from Human Embryonic Stem Cells Correct Hyperglycemia in SCID/NOD Mice,an Animal Model of Diabetes

Background

Human pancreatic islet transplantation is a prospective curative treatment for diabetes. However, the lack of donor pancreases greatly limits this approach. One approach to overcome the limited supply of donor pancreases is to generate functional islets from human embryonic stem cells (hESCs), a cell line with unlimited proliferative capacity, through rapid directed differentiation. This study investigated whether pancreatic insulin-producing cells (IPCs) differentiated from hESCs could correct hyperglycemia in severe combined immunodeficient (SCID)/non-obese diabetic (NOD) mice, an animal model of diabetes.

Methods

We generated pancreatic IPCs from two hESC lines, YT1 and YT2, using an optimized four-stage differentiation protocol in a chemically defined culture system. Then, about 5–7×10⁶ differentiated cells were transplanted into the epididymal fat pad of SCID/NOD mice (n = 20). The control group were transplanted with undifferentiated hESCs (n = 6). Graft survival and function were assessed using immunohistochemistry, and measuring serum human C-peptide and blood glucose levels.

Results

The pancreatic IPCs were generated by the four-stage differentiation protocol using hESCs. About 17.1% of differentiated cells expressed insulin, as determined by flow cytometry. These cells secreted insulin/C-peptide following glucose stimulation, similarly to adult human islets. Most of these IPCs co-expressed mature β cell-specific markers, including human C-peptide, GLUT2, PDX1, insulin, and glucagon. After implantation into the epididymal fat pad of SCID/NOD mice, the hESC-derived pancreatic IPCs corrected hyperglycemia for ≥8 weeks. None of the animals transplanted with pancreatic IPCs developed tumors during the time. The mean survival of recipients was increased by implanted IPCs as compared to implanted undifferentiated hESCs (P<0.0001).

Conclusions

The results of this study confirmed that human terminally differentiated pancreatic IPCs derived from hESCs can correct hyperglycemia in SCID/NOD mice for ≥8 weeks.     

Insulin-Producing Cells Differentiated from Human Bone Marrow Mesenchymal Stem Cells In Vitro Ameliorate Streptozotocin-Induced Diabetic Hyperglycemia

Background

The two major obstacles in the successful transplantation of islets for diabetes treatment are inadequate supply of insulin-producing tissue and immune rejection. Induction of the differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) into insulin-producing cells (IPCs) for autologous transplantation may alleviate those limitations.

Methods

hMSCs were isolated and induced to differentiate into IPCs through a three-stage differentiation protocol in a defined media with high glucose, nicotinamide, and exendin-4. The physiological characteristics and functions of IPCs were then evaluated. Next, about 3 × 10⁶ differentiated cells were transplanted into the renal sub-capsular space of streptozotocin (STZ)-induced diabetic nude mice. Graft survival and function were assessed by immunohistochemistry, TUNEL staining and measurements of blood glucose levels in the mice.

Results

The differentiated IPCs were characterized by Dithizone (DTZ) positive staining, expression of pancreatic β-cell markers, and human insulin secretion in response to glucose stimulation. Moreover, 43% of the IPCs showed L-type Ca²⁺ channel activity and similar changes in intracellular Ca²⁺ in response to glucose stimulation as that seen in pancreatic β-cells in the process of glucose-stimulated insulin secretion. Transplantation of functional IPCs into the renal subcapsular space of STZ-induced diabetic nude mice ameliorated the hyperglycemia. Immunofluorescence staining revealed that transplanted IPCs sustainably expressed insulin, c-peptide, and PDX-1 without apparent apoptosis in vivo.

Conclusions

IPCs derived from hMSCs in vitro can ameliorate STZ-induced diabetic hyperglycemia, which indicates that these hMSCs may be a promising approach to overcome the limitations of islet transplantation.