Growth inhibitors promote differentiation of insulin-producing tissue from embryonic stem cells

Current technology and industrialization status of cell-cultivated meat

Interest and investment in cultivated meat are increasing because of the realization that it can effectively supply sufficient food resources and reduce the use of livestock. Nevertheless, accurate information on the specific technologies used for cultivated meat production and the characteristics of cultivated meat is lacking. Authorization for the use of cultivated meat is already underway in the United States, Singapore, and Israel, and other major countries are also expected to approve cultivated meat as food once the details of the intricate process of producing cultivated meat, which encompasses stages such as cell proliferation, differentiation, maturation, and assembly, is thoroughly established. The development and standardization of mass production processes and safety evaluations must precede the industrialization and use of cultivated meat as food. However, the technology for the industrialization of cultivated meat is still in its nascent stage, and the mass production process has not yet been established. The mass production process of cultivated meat may not be easy to disclose because it is related to the interests of several companies or research teams. However, the overall research flow shows that equipment development for mass production and cell acquisition, proliferation, and differentiation, as well as for three-dimensional production supports and bioreactors have not yet been completed. Therefore, additional research on the mass production process and safety of cultivated meat is essential. The consumer's trust in the cultivated meat products and production technologies recently disclosed by some companies should also be analyzed and considered for guiding future developments in this industry. Furthermore, close monitoring by academia and the government will be necessary to identify fraud in the cultivated meat industry.

Optimizing Generation of Stem Cell-Derived Islet Cells

Islet transplantation is a highly effective treatment for select patients with type 1 diabetes. Unfortunately, current use is limited to those with brittle disease due to donor limitations and immunosuppression requirements. Discovery of factors for induction of pluripotent stem cells from adult somatic cells into a malleable state has reinvigorated the possibility of autologous-based regenerative cell therapies. Similarly, recent progress in allogeneic human embryonic stem cell islet products is showing early success in clinical trials. Describing safe and standardized differentiation protocols with clear pathways to optimize yield and minimize off-target growth is needed to efficiently move the field forward. This review discusses current islet differentiation protocols with a detailed break-down of differentiation stages to guide step-wise controlled generation of functional islet products.

The negative regulation of gene expression by microRNAs as key driver of inducers and repressors of cardiomyocyte differentiation

Cardiac muscle damage-induced loss of cardiomyocytes (CMs) and dysfunction of the remaining ones leads to heart failure, which nowadays is the number one killer worldwide. Therapies fostering effective cardiac regeneration are the holy grail of cardiovascular research to stop the heart failure epidemic. The main goal of most myocardial regeneration protocols is the generation of new functional CMs through the differentiation of endogenous or exogenous cardiomyogenic cells. Understanding the cellular and molecular basis of cardiomyocyte commitment, specification, differentiation and maturation is needed to devise innovative approaches to replace the CMs lost after injury in the adult heart. The transcriptional regulation of CM differentiation is a highly conserved process that require sequential activation and/or repression of different genetic programs. Therefore, CM differentiation and specification have been depicted as a step-wise specific chemical and mechanical stimuli inducing complete myogenic commitment and cell-cycle exit. Yet, the demonstration that some microRNAs are sufficient to direct ESC differentiation into CMs and that four specific miRNAs reprogram fibroblasts into CMs show that CM differentiation must also involve negative regulatory instructions. Here, we review the mechanisms of CM differentiation during development and from regenerative stem cells with a focus on the involvement of microRNAs in the process, putting in perspective their negative gene regulation as a main modifier of effective CM regeneration in the adult heart.

In vitro generation of transplantable insulin-producing cells from canine adipose-derived mesenchymal stem cells

Canine mesenchymal stem cells (cMSCs) have potential applications for regenerative therapy, including the generation of insulin-producing cells (IPCs) for studying and treating diabetes. In this study, we established a useful protocol for generating IPCs from canine adipose mesenchymal stem cells (cAD-MSCs). Subsequently, in vitro preservation of pluronic F127-coated alginate (ALGPA)-encapsulated cAD-MSC-derived IPCs was performed to verify ready-to-use IPCs. IPCs were induced from cAD-MSCs with the modulated three-stepwise protocol. The first step of definitive endoderm (DE) induction showed that the cooperation of Chir99021 and Activin A created the effective production of Sox17-expressed DE cells. The second step for pancreatic endocrine (PE) progenitor induction from DE indicated that the treatment with taurine, retinoic acid, FGF2, EGF, TGFβ inhibitor, dorsomorphin, nicotinamide, and DAPT showed the significant upregulation of the pancreatic endocrine precursor markers Pdx1 and Ngn3. The last step of IPC production, the combination of taurine, nicotinamide, Glp-1, forskolin, PI3K inhibitor, and TGFβ inhibitor, yielded efficiently functional IPCs from PE precursors. Afterward, the maintenance of ALGPA-encapsulated cAD-MSC-derived IPCs with VSCBIC-1, a specialized medium, enhanced IPC properties. Conclusion, the modulated three-stepwise protocol generates the functional IPCs. Together, the encapsulation of cAD-MSC-derived IPCs and the cultivation with VSCBIC-1 enrich the maturation of generated IPCs.

Therapeutic effects of stem cells in different body systems, a novel method that is yet to gain trust: A comprehensive review

Stem cell therapy has been used to treat several types of diseases, and it is expected that its therapeutic uses shall increase as novel lines of evidence begin to appear. Furthermore, stem cells have the potential to make new tissues and organs. Thus, some scientists propose that organ transplantation will significantly rely on stem cell technology and organogenesis in the future. Stem cells and its robust potential to differentiate into specific types of cells and regenerate tissues and body organs, have been investigated by numerous clinician scientists and researchers for their therapeutic effects. Degenerative diseases in different organs have been the main target of stem cell therapy. Neurodegenerative diseases such as Alzheimer's, musculoskeletal diseases such as osteoarthritis, congenital cardiovascular diseases, and blood cell diseases such as leukemia are among the health conditions that have benefited from stem cell therapy advancements. One of the most challenging parts of the process of incorporating stem cells into clinical practice is controlling their division and differentiation potentials. Sometimes, their potential for  uncontrolled growth will make these cells tumorigenic. Another caveat in this process is the ability to control the differentiation process. While stem cells can easily differentiate into a wide variety of cells,  a paracrine effect controlled activity, being in an appropriate medium will cause abnormal differentiation leading to treatment failure. In this review, we aim to provide an overview of the therapeutic effects of stem cells in diseases of various organ systems. In order to advance this new treatment to its full potential, researchers should focus on establishing methods to control the differentiation process, while policymakers should take an active role in providing adequate facilities and equipment for these projects. Large population clinical trials are a necessary tool that will help build trust in this method. Moreover, improving social awareness about the advantages and adverse effects of stem cell therapy is required to develop a rational demand in the society, and consequently, healthcare systems should consider established stem cell-based therapeutic methods in their treatment algorithms.

Transcriptome analysis of islets from diabetes-resistant and diabetes-prone obese mice reveals novel gene regulatory networks involved in beta-cell compensation and failure

The mechanisms underpinning beta-cell compensation for obesity-associated insulin resistance and beta-cell failure in type 2 diabetes remain poorly understood. We used a large-scale strategy to determine the time-dependent transcriptomic changes in islets of diabetes-prone db/db and diabetes-resistant ob/ob mice at 6 and 16 weeks of age. Differentially expressed genes were subjected to cluster, gene ontology, pathway and gene set enrichment analyses. A distinctive gene expression pattern was observed in 16 week db/db islets in comparison to the other groups with alterations in transcriptional regulators of islet cell identity, upregulation of glucose/lipid metabolism, and various stress response genes, and downregulation of specific amino acid transport and metabolism genes. In contrast, ob/ob islets displayed a coordinated downregulation of metabolic and stress response genes at 6 weeks of age, suggestive of a preemptive reconfiguration in these islets to lower the threshold of metabolic activation in response to increased insulin demand thereby preserving beta-cell function and preventing cellular stress. In addition, amino acid transport and metabolism genes were upregulated in ob/ob islets, suggesting an important role of glutamate metabolism in beta-cell compensation. Gene set enrichment analysis of differentially expressed genes identified the enrichment of binding motifs for transcription factors, FOXO4, NFATC1, and MAZ. siRNA-mediated knockdown of these genes in MIN6 cells altered cell death, insulin secretion, and stress gene expression. In conclusion, these data revealed novel gene regulatory networks involved in beta-cell compensation and failure. Preemptive metabolic reconfiguration in diabetes-resistant islets may dampen metabolic activation and cellular stress during obesity.

Immunopathology of Type 1 Diabetes and Immunomodulatory Effects of Stem Cells: A Narrative Review of the Literature

Type 1 Diabetes (T1D) is a complex autoimmune disorder which occurs as a result of an intricate series of pathologic interactions between pancreatic β-cells and a wide range of components of both the innate and the adaptive immune systems. Stem-cell therapy, a recently-emerged potentially therapeutic option for curative treatment of diabetes, is demonstrated to cause significant alternations to both different immune cells such as macrophages, natural killer (NK) cells, dendritic cells, T cells, and B cells and non-cellular elements including serum cytokines and different components of the complement system. Although there exists overwhelming evidence indicating that the documented therapeutic effects of stem cells on patients with T1D is primarily due to their potential for immune regulation rather than pancreatic tissue regeneration, to date, the precise underlying mechanisms remain obscure. On the other hand, immune-mediated rejection of stem cells remains one of the main obstacles to regenerative medicine. Moreover, the consequences of efferocytosis of stem-cells by the recipients' lung-resident macrophages have recently emerged as a responsible mechanism for some immune-mediated therapeutic effects of stem-cells. This review focuses on the nature of the interactions amongst different compartments of the immune systems which are involved in the pathogenesis of T1D and provides explanation as to how stem cell-based interventions can influence immune system and maintain the physiologic equilibrium.

Combination treatment of autologous bone marrow stem cell transplantation and hyperbaric oxygen therapy for type 2 diabetes mellitus: A randomized controlled trial

The objective of this study was to compare standard treatment versus the combination of intrapancreatic autologous stem cell (ASC) infusion and hyperbaric oxygen treatment (HBOT) before and after ASC in the metabolic control of patients with type 2 diabetes mellitus (T2DM). This study was a prospective, randomized controlled trial. The combined intervention consisted of 10 sessions of HBOT before the intrapancreatic infusion of ASC and 10 sessions afterwards. ASCs were infused into the main arterial supply of the pancreas to maximize the presence of the stem cells where the therapeutic effect is most desired. A total of 23 patients were included (control group = 10, intervention group = 13). Age, gender, diabetes duration, number of medications taken, body weight and height, and insulin requirements were recorded at baseline and every three months. Also, body mass index, fasting plasma glucose, C-peptide, and HbA1c, C-peptide/glucose ratio (CPGR) were measured every three months for one year. HbA1c was significantly lower in the intervention group compared with control throughout follow-up. Overall, 77% of patients in the intervention group and 30% of patients in the control group demonstrated a decrease of HbA1c at 180 days (compared with baseline) of at least 1 unit. Glucose levels were significantly lower in the intervention group at all timepoints during follow-up. C-peptide levels were significantly higher in the intervention group during follow-up and at one year: 1.9 ± 1.0 ng/mL versus 0.7 ± 0.4 ng/mL in intervention versus control groups, respectively, p = 0.0021. CPGR was higher in the intervention group at all controls during follow-up. The requirement for insulin was significantly lower in the intervention group at 90, 180, 270, and 365 days. Combined therapy of intrapancreatic ASC infusion and HBOT showed increased metabolic control and reduced insulin requirements in patients with T2DM compared with standard treatment.

Comparative study of xeno-free induction protocols for neural differentiation of human dental pulp stem cells in vitro

OBJECTIVE

To compare three different xeno-free protocols for neural differentiation of human dental pulp stem cells (DPSC).

METHODS

DPSC were treated with three different media to induce neural differentiation namely N1 (DMEM for 5 days), N2 (PSC neural induction media for 7 days) and N3 (neural media with B27 supplement, 40 ng/ml bFGF and 20 ng/ml EGF for 21 days). Cell proliferation (MTS assay), morphology, gene (qPCR for NESTIN, VIMENTIN, TUB-3, ENO2, NF-M and NF-H) and protein expression (flow cytometry) of neurogenic markers were assessed at different time points and compared to untreated cells (DMEM supplemented with 10% FBS). Statistical analysis was performed with global significance level of 5%.

RESULTS

N1 and N2 formulations increased the genetic expression of two out of six genes TUB-3, NF-M and TUB-3, NF-H, respectively, whereas N3 elevated the expression of all genes by the late stage. N3 also stimulated protein expression for NESTIN, TUB-3 and NF-H. Cells treated with both N2 and N3 presented neuron-like morphology, decreased proliferation and expression of stemness genes at protocol end point.

CONCLUSION

N3 was the most effective formulation in promoting a neurogenic shift in gene and protein expression. Cells provided with the N3 formulation exhibited neuron-like morphology, elaborating axonal-like projections concomitant with cell cycle withdrawal and reduced expression of stemness genes indicating greater commitment to a neurogenic lineage.

Electrospun Nanofibers for Diabetes: Tissue Engineering and Cell-Based Therapies

Diabetes mellitus is an autoimmune disease which causes loss of insulin secretion producing hyperglycemia by promoting progressive destruction of pancreatic β cells. An ideal therapeutic approach to manage diabetes mellitus is pancreatic β cells replacement. The aim of this review article was to evaluate the role of nanofibrous scaffolds and stem cells in the treatment of diabetes mellitus. Various studies have pointed out that application of electrospun biomaterials has considerably attracted researchers in the field of tissue engineering. The principles of cell therapy for diabetes have been reviewed in the first part of this article, while the usability of tissue engineering as a new therapeutic approach is discussed in the second part.

Short-Term Protocols to Obtain Insulin-Producing Cells from Rat Adipose Tissue: Signaling Pathways and In Vivo Effect

Studies using mesenchymal stromal cells (MSCs) as a source of insulin-secreting cells (IPCs) are a promising path in the pursuit for diabetes therapy. Here, we investigate three short-term differentiation protocols in order to generate IPCs from autologous adipose-derived stromal cells (ADSCs) with an expressive insulin-secreting profile in vitro and in vivo, as well as the signaling pathways involved in the chosen differentiation protocols. We extracted and cultured ADSCs and differentiated them into IPCs, using three different protocols with different inductors. Afterwards, the secretory profile was analyzed and IPCs differentiated in exendin-4/activin A medium, which presented the best secretory profile, was implanted in the kidney subcapsular region of diabetic rats. All protocols induced the differentiation, but media supplemented with exendin-4/activin A or resveratrol induced the expression and secretion of insulin more efficiently, and only the exendin-4/activin-A-supplemented medium generated an insulin secretion profile more like β-cells, in response to glucose. The PI3K/Akt pathway seems to play a negative role in IPC differentiation; however, the differentiation of ADSCs with exendin-4/activin A positively modulated the p38/MAPK pathway. Resveratrol medium activated the Jak/STAT3 pathway and generated IPCs apparently less sensitive to insulin and insulin-like receptors. Finally, the implant of IPCs with the best secretory behavior caused a decrease in hyperglycemia after one-week implantation in diabetic rats. Our data provide further information regarding the generation of IPCs from ADSCs and strengthen evidence to support the use of MSCs in regenerative medicine, specially the use of exendin-4/activin A to produce rapid and effectively IPCs with significant in vivo effects.

Redefining the signaling pathways from pluripotency to pancreas development: In vitro β-cell differentiation

Pancreatic β-cells are destroyed by the immune system, in type 1 diabetes (T1D) and are impaired by glucose insensitivity in type 2 diabetes (T2D). Islet-cells transplantation is a promising therapeutic approach based on in vitro differentiation of pluripotent stem cells (PSCs) to insulin-producing cells (IPCs). According to evolutionary stages in β-cell development, there are several distinct checkpoints; each one has a unique characteristic, including definitive endoderm (DE), primitive gut (PG), posterior foregut (PF), pancreatic epithelium (PE), endocrine precursor (EP), and immature β-cells up to functional β-cells. A better understanding of the gene regulatory networks (GRN) and associated transcription factors in each specific developmental stage, guarantees the achievement of the next successful checkpoints and ensures an efficient β-cell differentiation procedure. The new findings in signaling pathways, related to the development of the pancreas are discussed here, including Wnt, Activin/Nodal, FGF, BMP, retinoic acid (RA), sonic hedgehog (Shh), Notch, and downstream regulators, required for β-cell commitment. We also summarized different approaches in the IPCs protocol to conceptually define a standardized system, leading to the creation of a reproducible method for β-cell differentiation. To normalize blood glucose level in diabetic mice, the replacement therapy in the early differentiation stage, such as EP stages was associated with better outcome when compared with the fully differentiated β-cells' graft.

Current Status of Stem Cell Treatment for Type I Diabetes Mellitus

BACKGROUND

Diabetes mellitus is a major health concern in current scenario which has been found to affect people of almost all ages. The disease has huge impact on global health; therefore, alternate methods apart from insulin injection are being explored to cure diabetes. Therefore, this review mainly focuses on the current status and therapeutic potential of stem cells mainly mesenchymal stem cells (MSCs) for Type 1 diabetes mellitus in preclinical animal models as well as humans.

METHODS

Current treatment for Type 1 diabetes mellitus mainly includes use of insulin which has its own limitations and also the underlying mechanism of diseases is still not explored. Therefore, alternate methods to cure diabetes are being explored. Stem cells are being investigated as an alternative therapy for treatment of various diseases including diabetes. Few preclinical studies have also been conducted using undifferentiated MSCs as well as in vitro MSCs differentiated into β islet cells.

RESULTS

These stem cell transplant studies have highlighted the benefits of MSCs, which have shown promising results. Few human trials using stem cells have also affirmed the potential of these cells in alleviating the symptoms.

CONCLUSION

Stem cell transplantation may prove to be a safe and effective treatment for patients with Type 1 diabetes mellitus.

Fabrication of agarose concave petridish for 3D-culture microarray method for spheroids formation of hepatic cells

Liver is one of the most important organ in the body. But there are many limitations about liver transplantation for liver failure. It is quite important to develop the xenogeneic biological liver for providing an alternation to transplantation or liver regeneration. In this paper, we proposed a method to construct a novel kind of agarose 3D-culture concave microwell array for spheroids formation of hepatic cells. Using the 3D printing method, the microwell array was fabricated with an overall size of 6.4 mm × 6.4 mm, containing 121 microwells with 400 μm width/400 μm thickness. By exploiting the Polydimethylsiloxane (PDMS) membranes as a bridge, we finally fabricated the agarose one. We co-cultured three types of liver cells with bionics design in the microwell arrays. Using the methods described above, the resulting co-formed hepatocyte spheroids maintained the high viability and stable liver-specific functions. This engineered agarose concave microwell array could be a potentially useful tool for forming the elements for biological liver support. After developing the complete system, we also would consider to scale up the application of this system. It will be not only applied to the therapy of human organ damage, but also to the development of disease models and drug screening models.

The journey of islet cell transplantation and future development

Intraportal islet transplantation has proven to be efficacious in preventing severe hypoglycemia and restoring insulin independence in selected patients with type 1 diabetes. Multiple islet infusions are often required to achieve and maintain insulin independence. Many challenges remain in clinical islet transplantation, including substantial islet cell loss early and late after islet infusion. Contributions to graft loss include the instant blood-mediated inflammatory reaction, potent host auto- and alloimmune responses, and beta cell toxicity from immunosuppressive agents. Protective strategies are being tested to circumvent several of these events including exploration of alternative transplantation sites, stem cell-derived insulin producing cell therapies, co-transplantation with mesenchymal stem cells or exploration of novel immune protective agents. Herein, we provide a brief introduction and history of islet cell transplantation, limitations associated with this procedure and methods to alleviate islet cell loss as a means to improve engraftment outcomes.

Addressing Stem Cell Therapeutic Approaches in Pathobiology of Diabetes and Its Complications

High morbidity and mortality of diabetes mellitus (DM) throughout the human population is a serious threat which needs to be addressed cautiously. Type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) are most prevalent forms. Disruption in insulin regulation and resistance leads to increased formation and accumulation of advanced end products (AGEs), which further enhance oxidative and nitrosative stress leading to microvascular (retinopathy, neuropathy, and nephropathy) and macrovascular complications. These complications affect the normal function of organ and tissues and may cause life-threatening disorders, if hyperglycemia persists and improperly controlled. Current and traditional treatment procedures are only focused on to regulate the insulin level and do not cure the diabetic complications. Pancreatic transplantation seemed a viable alternative; however, it is limited due to lack of donors. Cell-based therapy such as stem cells is considered as a promising therapeutic agent against DM and diabetic complications owing to their multilineage differentiation and regeneration potential. Previous studies have demonstrated the various impacts of both pluripotent and multipotent stem cells on DM and its micro- and macrovascular complications. Therefore, this review summarizes the potential of stem cells to treat DM and its related complications.

FGF-2b and h-PL Transform Duct and Non-Endocrine Human Pancreatic Cells into Endocrine Insulin Secreting Cells by Modulating Differentiating Genes

Background: Diabetes mellitus (DM) is a multifactorial disease orphan of a cure. Regenerative medicine has been proposed as novel strategy for DM therapy. Human fibroblast growth factor (FGF)-2b controls β-cell clusters via autocrine action, and human placental lactogen (hPL)-A increases functional β-cells. We hypothesized whether FGF-2b/hPL-A treatment induces β-cell differentiation from ductal/non-endocrine precursor(s) by modulating specific genes expression. Methods: Human pancreatic ductal-cells (PANC-1) and non-endocrine pancreatic cells were treated with FGF-2b plus hPL-A at 500 ng/mL. Cytofluorimetry and Immunofluorescence have been performed to detect expression of endocrine, ductal and acinar markers. Bromodeoxyuridine incorporation and annexin-V quantified cells proliferation and apoptosis. Insulin secretion was assessed by RIA kit, and electron microscopy analyzed islet-like clusters. Results: Increase in PANC-1 duct cells de-differentiation into islet-like aggregates was observed after FGF-2b/hPL-A treatment showing ultrastructure typical of islets-aggregates. These clusters, after stimulation with FGF-2b/hPL-A, had significant (p < 0.05) increase in insulin, C-peptide, pancreatic and duodenal homeobox 1 (PDX-1), Nkx2.2, Nkx6.1, somatostatin, glucagon, and glucose transporter 2 (Glut-2), compared with control cells. Markers of PANC-1 (Cytokeratin-19, MUC-1, CA19-9) were decreased (p < 0.05). These aggregates after treatment with FGF-2b/hPL-A significantly reduced levels of apoptosis. Conclusions: FGF-2b and hPL-A are promising candidates for regenerative therapy in DM by inducing de-differentiation of stem cells modulating pivotal endocrine genes.

Comparison of Fetal Porcine Aggregates of Purified β-Cells versus Islet-Like Cell Clusters as a Treatment of Diabetes

Fetal pig islet-like cell clusters (ICCs) have the potential to reverse diabetes 1–5 months after transplantation. In a fetal ICC, however, β-cells constitute only 6–8% of the cells, in contrast to 65% in an adult pig islet. Attempts to purify fetal β-cells from cell clusters and compare their function to that of ICCs have not been shown previously. β-Cells were purified from ICCs isolated from the fetal pig pancreas. These were then aggregated and maintained in culture for 3 days. ICCs were isolated from fetal pig pancreas and allowed to round up in culture for 3 days. Transplantation of aggregates and ICCs (10,000 and 12,600, respectively) into diabetic immunoincompetent mice resulted in normoglycemia at 18 ± 2 and 8 ± 1 weeks, respectively (p = 0.0006). Removal of grafts after normalization of blood glucose levels resulted in rapid return of hyperglycemia in both groups. In conclusion, a purified population of immature β-cells can be produced from the fetal pig pancreas. The reason these cells take longer than ICCs to reverse diabetes when transplanted is postulated to be because of the relative lack of precursor cells from which β-cells differentiate. This finding may have implications for stem cell therapy, as other cell types, other than purified β-cells, may be necessary for appropriate function in vivo.

Role of PI3K p110β in the differentiation of human embryonic stem cells into islet-like cells

To investigate the effects of the PI3K inhibitors on the differentiation of insulin-producing cells derived from human embryonic stem cells. Here, we report that human embryonic stem cells induced by phosphatidylinositol-3-kinase (PI3K) p110β inhibitors could produce more mature islet-like cells. Findings were validated by immunofluorescence analysis, quantitative real-time PCR, insulin secretion in vitro and cell transplantation for the diabetic SCID mice. Immunofluorescence analysis revealed that unihormonal insulin-positive cells were predominant in cultures with rare polyhormonal cells. Real-time PCR data showed that islet-like cells expressed key markers of pancreatic endocrine hormones and mature pancreatic β cells including MAFA. Furthermore, this study showed that the expression of most pancreatic endocrine hormones was similar between groups treated with the LY294002 (nonselective PI3K inhibitor) and TGX-221 (PI3K isoform selective inhibitors of class 1β) derivatives. However, the level of insulin mRNA in TGX-221-treated cells was significantly higher than that in LY294002-treated cells. In addition, islet-like cells displayed glucose-stimulated insulin secretion in vitro. After transplantation, islet-like cells improved glycaemic control and ameliorated the survival outcome in diabetic mice. This study demonstrated an important role for PI3K p110β in regulating the differentiation and maturation of islet-like cells derived from human embryonic stem cells.

Gemcitabine Enhances Kras-MEK-Induced Matrix Metalloproteinase-10 Expression Via Histone Acetylation in Gemcitabine-Resistant Pancreatic Tumor-initiating Cells

OBJECTIVES

Advanced pancreatic ductal adenocarcinoma is resistant to systemic chemotherapy, resulting in a poor prognosis. We previously isolated a human pancreatic tumor-initiating cell line, KMC07, from a patient with acquired resistance to gemcitabine chemotherapy. To improve the anticancer effects of gemcitabine, we investigated the molecular mechanism of KMC07 cells' resistance to gemcitabine.

METHODS

KMC07 cells were treated with gemcitabine, then gene expression and functional analyses performed using microarray, the quantitative polymerase chain reaction, immunoblotting, immunohistochemistry, chromatin immunoprecipitation, and cell transplantation into nude mice.

RESULTS

KMC07 cells, but not BxPC-3, PANC-1, MIA PaCa-2, or AsPC-1 cells, expressed matrix metalloproteinase-10 mRNA, the expression level of which was enhanced by gemcitabine. KMC07 cells were shown to carry a constitutively active Kras mutation, and a MEK inhibitor suppressed matrix metalloproteinase-10 mRNA expression. Gemcitabine enhanced histone H3 acetylation at the matrix metalloproteinase-10 promoter, and a histone acetyltransferase inhibitor reduced gemcitabine-enhanced matrix metalloproteinase-10 mRNA expression. Gemcitabine induced expression of matrix metalloproteinase-10 protein in KMC07-derived pancreatic tumors in vivo.

CONCLUSIONS

We demonstrated constitutive activation of the Kras-MEK matrix metalloproteinase-10 signaling pathway in KMC07 cells that was enhanced by gemcitabine through histone acetylation. Our results may provide novel insights into gemcitabine-based treatment for gemcitabine-resistant pancreatic ductal adenocarcinoma.

The quest to make fully functional human pancreatic beta cells from embryonic stem cells: climbing a mountain in the clouds

The production of fully functional insulin-secreting cells to treat diabetes is a major goal of regenerative medicine. In this article, I review progress towards this goal over the last 15 years from the perspective of a beta cell biologist. I describe the current state-of-the-art, and speculate on the general approaches that will be required to identify and achieve our ultimate goal of producing functional beta cells. The need for deeper phenotyping of heterogeneous cultures of stem cell derived islet-like cells in parallel with a better understanding of the heterogeneity of the target cell type(s) is emphasised. This deep phenotyping should include high-throughput single-cell analysis, as well as comprehensive 'omics technologies to provide unbiased characterisation of cell products and human beta cells. There are justified calls for more detailed and well-powered studies of primary human pancreatic beta cell physiology, and I propose online databases of standardised human beta cell responses to physiological stimuli, including both functional and metabolomic/proteomic/transcriptomic profiles. With a concerted, community-wide effort, including both basic and applied scientists, beta cell replacement will become a clinical reality for patients with diabetes.

Enhanced Adipogenic Differentiation of Human Adipose-Derived Stem Cells in an In Vitro Microenvironment: The Preparation of Adipose-Like Microtissues Using a Three-Dimensional Culture

The application of stem cells for cell therapy has been extensively studied in recent years. Among the various types of stem cells, human adipose tissue-derived stem cells (ASCs) can be obtained in large quantities with relatively few passages, and they possess a stable quality. ASCs can differentiate into a number of cell types, such as adipose cells and ectodermal cells. We therefore focused on the in vitro microenvironment required for such differentiation and attempted to induce the differentiation of human stem cells into microtissues using a microelectromechanical system. We first evaluated the adipogenic differentiation of human ASC spheroids in a three-dimensional (3D) culture. We then created the in vitro microenvironment using a 3D combinatorial TASCL device and attempted to induce the adipogenic differentiation of human ASCs. The differentiation of human ASC spheroids cultured in maintenance medium and those cultured in adipocyte differentiation medium was evaluated via Oil red O staining using lipid droplets based on the quantity of accumulated triglycerides. The differentiation was confirmed in both media, but the human ASCs in the 3D cultures contained higher amounts of triglycerides than those in the 2D cultures. In the short culture period, greater adipogenic differentiation was observed in the 3D cultures than in the 2D cultures. The 3D culture using the TASCL device with adipogenic differentiation medium promoted greater differentiation of human ASCs into adipogenic lineages than either a 2D culture or a culture using a maintenance medium. In summary, the TASCL device created a hospitable in vitro microenvironment and may therefore be a useful tool for the induction of differentiation in 3D culture. The resultant human ASC spheroids were "adipose-like microtissues" that formed spherical aggregation perfectly and are expected to be applicable in regenerative medicine as well as cell transplantation.

New Insights into Diabetes Cell Therapy

Since insulin discovery, islet transplantation was the first protocol to show the possibility to cure patients with type 1 diabetes using low-risk procedures. The scarcity of pancreas donors triggered a burst of studies focused on the production of new β cells in vitro. These were rapidly dominated by pluripotent stem cells (PSCs) demonstrating diabetes-reversal potential in diabetic mice. Subsequent enthusiasm fostered a clinical trial with immunoisolated embryonic-derived pancreatic progenitors. Yet safety is the Achilles' heel of PSCs, and a whole branch of β cell engineering medicine focuses on transdifferentiation of adult pancreatic cells. New data showed the possibility to chemically stimulate acinar or α cells to undergo β cell neogenesis and provide opportunities to intervene in situ without the need for a transplant, at least after weighing benefits against systemic adverse effects. The current studies suggested the pancreas as a reservoir of facultative progenitors (e.g., in the duct lining) could be exploited ex vivo for expansion and β cell differentiation in timely fashion and without the hurdles of PSC use. Diabetes cell therapy is thus a growing field not only with great potential but also with many pitfalls to overcome for becoming fully envisioned as a competitor to the current treatment standards.

Engineering pancreatic tissues from stem cells towards therapy

Pancreatic islet transplantation is performed as a potential treatment for type 1 diabetes mellitus. However, this approach is significantly limited due to the critical shortage of islet sources. Recently, a number of publications have developed protocols for directed β-cell differentiation of pluripotent cells, such as embryonic stem (ES) or induced pluripotent stem (iPS) cells. Decades of studies have led to the development of modified protocols that recapitulate molecular developmental cues by combining various growth factors and small molecules with improved efficiency. However, the later step of pancreatic differentiation into functional β-cells has yet to be satisfactory in vitro, highlighting alternative approach by recapitulating spatiotemporal multicellular interaction in three-dimensional (3D) culture. Here, we summarize recent progress in the directed differentiation into pancreatic β-cells with a focus on both two-dimensional (2D) and 3D differentiation settings. We also discuss the potential transplantation strategies in combination with current bioengineering approaches towards diabetes therapy.

•

Transplantation of stem cell derived pancreatic progenitors is a possible approach for generating mature β-cell in vivo.

•

Promise of 3-D (or 4-D) culture has started to be explored by reconstituting pancreatic tissue structures.

•

Self-condensation culture is a basic technique of integrating multiple heterotypic lineages including vasculatures.

•

Bioengineering approach has been combined for developing effective transplant strategies.

In Vitro Differentiation of Insulin Secreting Cells from Mouse Bone Marrow Derived Stage-Specific Embryonic Antigen 1 Positive Stem Cells

OBJECTIVE

Bone marrow has recently been recognized as a novel source of stem cells for the treatment of wide range of diseases. A number of studies on murine bone mar- row have shown a homogenous population of rare stage-specific embryonic antigen 1 (SSEA-1) positive cells that express markers of pluripotent stem cells. This study focuses on SSEA-1 positive cells isolated from murine bone marrow in an attempt to differentiate them into insulin-secreting cells (ISCs) in order to investigate their differentiation potential for future use in cell therapy.

MATERIALS AND METHODS

This study is an experimental research. Mouse SSEA-1 positive cells were isolated by Magnetic-activated cell sorting (MACS) followed by characteriza- tion with flow cytometry. Induced SSEA-1 positive cells were differentiated into ISCs with specific differentiation media. In order to evaluate differentiation quality and analysis, dithizone (DTZ) staining was use, followed by reverse transcription polymerase chain reaction (RT-PCR), immunocytochemistry and insulin secretion assay. Statistical results were analyzed by one-way ANOVA.

RESULTS

The results achieved in this study reveal that mouse bone marrow contains a population of SSEA-1 positive cells that expresses pluripotent stem cells markers such as SSEA-1, octamer-binding transcription factor 4 (OCT-4) detected by immunocytochem- istry and C-X-C chemokine receptor type 4 (CXCR4) and stem cell antigen-1 (SCA-1) detected by flow cytometric analysis. SSEA-1 positive cells can differentiate into ISCs cell clusters as evidenced by their DTZ positive staining and expression of genes such as Pdx1 (pancreatic transcription factors), Ngn3 (endocrine progenitor marker), Insulin1 and Insulin2 (pancreaticβ-cell markers). Additionally, our results demonstrate expression of Pdx1 and Glut2 protein and insulin secretion in response to a glucose challenge in the differentiated cells.

CONCLUSION

Our study clearly demonstrates the potential of SSEA-1 positive cells to differentiate into insulin secreting cells in defined culture conditions for clinical ap- plications.

Current Science of Regenerative Medicine with Stem Cells

Regenerative medicine with stem cells holds great hope for the treatment of degenerative disease. The medical potential of embryonic stem cells remains relatively untapped at this point, and significant scientific hurdles remain to be overcome before these cells might be considered safe and effective for uses in patients. Meanwhile, adult stem cells have begun to show significant capabilities of their own in repair of damaged tissues, in both animal models and early patient trials.

Spheroid Formation and Evaluation of Hepatic Cells in a Three-Dimensional Culture Device

In drug discovery, it is very important to evaluate liver cells within an organism. Compared to 2D culture methods, the development of 3D culture techniques for liver cells has been successful in maintaining long-term liver functionality with the formation of a hepatic-specific structure. The key to performing drug testing is the establishment of a stable in vitro evaluation system. In this article, we report a Tapered Stencil for Cluster Culture (TASCL) device developed to create liver spheroids in vitro. The TASCL device will be applied as a toxicity evaluation system for drug discovery. The TASCL device was created with an overall size of 10 mm × 10 mm, containing 400 microwells with a top aperture (500 µm × 500 µm) and a bottom aperture (300 µm diameter circular) per microwell. We evaluated the formation, recovery, and size of HepG2 spheroids in the TASCL device. The formation and recovery were both nearly 100%, and the size of the HepG2 spheroids increased with an increase in the initial cell seeding density. There were no significant differences in the sizes of the spheroids among the microwells. In addition, the HepG2 spheroids obtained using the TASCL device were alive and produced albumin. The morphology of the HepG2 spheroids was investigated using FE-SEM. The spheroids in the microwells exhibited perfectly spherical aggregation. In this report, by adjusting the size of the microwells of the TASCL device, uniform HepG2 spheroids were created, and the device facilitated more precise measurements of the liver function per HepG2 spheroid. Our TASCL device will be useful for application as a toxicity evaluation system for drug testing.

Using stem cells to produce insulin

INTRODUCTION

Tremendous progress has been made in generating insulin-producing cells from pluripotent stem cells. The best outcome of the refined protocols became apparent in the first clinical trial announced by ViaCyte, based on the implantation of pancreatic progenitors that would further mature into functional insulin-producing cells inside the patient's body.

AREAS COVERED

Several groups, including ours, have contributed to improve strategies to generate insulin-producing cells. Of note, the latest results have gained a substantial amount of interest as a method to create a potentially functional and limitless supply of β-cell to revert diabetes mellitus. This review analyzes the accomplishments that have taken place over the last few decades, summarizes the state-of-art methods for β-cell replacement therapies based on the differentiation of embryonic stem cells into glucose-responsive and insulin-producing cells in a dish and discusses alternative approaches to obtain new sources of insulin-producing cells.

EXPERT OPINION

Undoubtedly, recent events preface the beginning of a new era in diabetes therapy. However, in our opinion, a number of significant hurdles still stand in the way of clinical application. We believe that the combination of the private and public sectors will accelerate the process of obtaining the desired safe and functional β-cell surrogates.

Engineered commensal bacteria reprogram intestinal cells into glucose-responsive insulin-secreting cells for the treatment of diabetes

The inactive full-length form of GLP-1(1-37) stimulates conversion of both rat and human intestinal epithelial cells into insulin-secreting cells. We investigated whether oral administration of human commensal bacteria engineered to secrete GLP-1(1-37) could ameliorate hyperglycemia in a rat model of diabetes by reprogramming intestinal cells into glucose-responsive insulin-secreting cells. Diabetic rats were fed daily with human lactobacilli engineered to secrete GLP-1(1-37). Diabetic rats fed GLP-1-secreting bacteria showed significant increases in insulin levels and, additionally, were significantly more glucose tolerant than those fed the parent bacterial strain. These rats developed insulin-producing cells within the upper intestine in numbers sufficient to replace ∼25-33% of the insulin capacity of nondiabetic healthy rats. Intestinal tissues in rats with reprogrammed cells expressed MafA, PDX-1, and FoxA2. HNF-6 expression was observed only in crypt epithelia expressing insulin and not in epithelia located higher on the villous axis. Staining for other cell markers in rats treated with GLP-1(1-37)-secreting bacteria suggested that normal function was not inhibited by the close physical proximity of reprogrammed cells. These results provide evidence of the potential for a safe and effective nonabsorbed oral treatment for diabetes and support the concept of engineered commensal bacterial signaling to mediate enteric cell function in vivo.

Recent developments in β-cell differentiation of pluripotent stem cells induced by small and large molecules

Human pluripotent stem cells, including human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), hold promise as novel therapeutic tools for diabetes treatment because of their self-renewal capacity and ability to differentiate into beta (β)-cells. Small and large molecules play important roles in each stage of β-cell differentiation from both hESCs and hiPSCs. The small and large molecules that are described in this review have significantly advanced efforts to cure diabetic disease. Lately, effective protocols have been implemented to induce hESCs and human mesenchymal stem cells (hMSCs) to differentiate into functional β-cells. Several small molecules, proteins, and growth factors promote pancreatic differentiation from hESCs and hMSCs. These small molecules (e.g., cyclopamine, wortmannin, retinoic acid, and sodium butyrate) and large molecules (e.g. activin A, betacellulin, bone morphogentic protein (BMP4), epidermal growth factor (EGF), fibroblast growth factor (FGF), keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), noggin, transforming growth factor (TGF-α), and WNT3A) are thought to contribute from the initial stages of definitive endoderm formation to the final stages of maturation of functional endocrine cells. We discuss the importance of such small and large molecules in uniquely optimized protocols of β-cell differentiation from stem cells. A global understanding of various small and large molecules and their functions will help to establish an efficient protocol for β-cell differentiation.

Three-Dimensional In Vitro Hepatic Constructs Formed Using Combinatorial Tapered Stencil for Cluster Culture (TASCL) Device

Attempts to create artificial liver tissue from various cells have been reported as an alternative method for liver transplantation and pharmaceutical testing. In the construction of artificial liver tissue, the selection of the cell source is the most important factor. However, if an appropriate environment (in vitro/in vivo) cannot be provided for various cells, it is not possible to obtain artificial liver tissue with the desired function. Therefore, we focused on the in vitro environment and produced liver tissues using MEMS technology. In the present study, we report a combinatorial TASCL device to prepare 3D cell constructs in vitro. The TASCL device was fabricated with an overall size of 10 mm × 10 mm with microwells and a top aperture (400 µm × 400 µm, 600 µm × 600 µm, 800 µm × 800 µm) and bottom aperture (40 µm × 40 µm, 80 µm × 80 µm, 160 µm × 160 µm) per microwell. The TASCL device can be easily installed on various culture dishes with tweezers. Using plastic dishes as the bottom surface of the combinatorial TASCL device, 3D hepatocyte constructs of uniform sizes (about ɸ 100 μm-ɸ 200 μm) were produced by increasing the seeding cell density of primary mouse hepatocytes. The 3D hepatocyte constructs obtained using the TASCL device were alive and secreted albumin. On the other hand, partially adhered primary mouse hepatocytes exhibited a cobblestone morphology on the collagen-coated bottom of the individual microwells using the combinatorial TASCL device. By changing the bottom substrate of the TASCL device, the culture environment of the cell constructs was easily changed to a 3D environment. The combinatorial TASCL device described in this report can be used quickly and simply. This device will be useful for preparing hepatocyte constructs for application in drug screening and cell medicine.

Differentiation into Endoderm Lineage: Pancreatic differentiation from Embryonic Stem Cells

The endoderm gives rise to digestive and respiratory tracts, thyroid, liver, and pancreas. Representative disease of endoderm lineages is type 1 diabetes resulting from destruction of the insulin-producing β cells. Generation of functional β cells from human embryonic stem (ES) cells in vitro can be practical, renewable cell source for replacement cell therapy for type 1 diabetes. It has been achieved by progressive instructive differentiation through each of the developmental stages. In this article, important studies of differentiation into pancreatic β cells from ES cells are reviewed through pancreatic developmental stages as definitive endoderm, primitive gut tube/foregut, and pancreatic cells. The investigation of differentiating ES cells from definitive endoderm to pancreas using signaling, arrays, and proteomics is also introduced.

Maturation of stem cell-derived beta-cells guided by the expression of urocortin 3

Type 1 diabetes (T1D) is a devastating disease precipitated by an autoimmune response directed at the insulin-producing beta-cells of the pancreas for which no cure exists. Stem cell-derived beta-cells show great promise for a cure as they have the potential to supply unlimited numbers of cells that could be derived from a patient's own cells, thus eliminating the need for immunosuppression. Current in vitro protocols for the differentiation of stem cell-derived beta-cells can successfully generate pancreatic endoderm cells. In diabetic rodents, such cells can differentiate further along the beta-cell lineage until they are eventually capable of restoring normoglycemia. While these observations demonstrate that stem cell-derived pancreatic endoderm has the potential to differentiate into mature, glucose-responsive beta-cells, the signals that direct differentiation and maturation from pancreatic endoderm onwards remain poorly understood. In this review, we analyze the sequence of events that culminates in the formation of beta-cells during embryonic development. and summarize how current protocols to generate beta-cells have sought to capitalize on this ontogenic template. We place particular emphasis on the current challenges and opportunities which occur in the later stages of beta-cell differentiation and maturation of transplantable stem cell-derived beta-cells. Another focus is on the question how the use of recently identified maturation markers such as urocortin 3 can be instrumental in guiding these efforts.

Efficient and simple production of insulin-producing cells from embryonal carcinoma stem cells using mouse neonate pancreas extract, as a natural inducer

An attractive approach to replace the destroyed insulin-producing cells (IPCs) is the generation of functional β cells from stem cells. Embryonal carcinoma (EC) stem cells are pluripotent cells which can differentiate into all cell types. The present study was carried out to establish a simple nonselective inductive culture system for generation of IPCs from P19 EC cells by 1–2 weeks old mouse pancreas extract (MPE). Since, mouse pancreatic islets undergo further remodeling and maturation for 2–3 weeks after birth, we hypothesized that the mouse neonatal MPE contains essential factors to induce in vitro differentiation of pancreatic lineages. Pluripotency of P19 cells were first confirmed by expression analysis of stem cell markers, Oct3/4, Sox-2 and Nanog. In order to induce differentiation, the cells were cultured in a medium supplemented by different concentrations of MPE (50, 100, 200 and 300 µg/ml). The results showed that P19 cells could differentiate into IPCs and form dithizone-positive cell clusters. The generated P19-derived IPCs were immunoreactive to proinsulin, insulin and insulin receptor beta. The expression of pancreatic β cell genes including, PDX-1, INS1 and INS2 were also confirmed. The peak response at the 100 µg/ml MPE used for investigation of EP300 and CREB1 gene expression. When stimulated with glucose, these cells synthesized and secreted insulin. Network analysis of the key transcription factors (PDX-1, EP300, CREB1) during the generation of IPCs resulted in introduction of novel regulatory candidates such as MIR17, and VEZF1 transcription factors, as well as MORN1, DKFZp761P0212, and WAC proteins. Altogether, we demonstrated the possibility of generating IPCs from undifferentiated EC cells, with the characteristics of pancreatic β cells. The derivation of pancreatic cells from EC cells which are ES cell siblings would provide a valuable experimental tool in study of pancreatic development and function as well as rapid production of IPCs for transplantation.

In vitro reconstitution of pancreatic islets

The lack of transplantable pancreatic islets is a serious problem that affects the treatment of patients with type 1 diabetes mellitus. Beta cells can be induced from various sources of stem or progenitor cells, including induced pluripotent stem cells in the near future; however, the reconstitution of islets from β cells in culture dishes is challenging. The generation of highly functional islets may require three-dimensional spherical cultures that resemble intact islets. This review discusses recent advances in the reconstitution of islets. Several factors affect the reconstitution of pseudoislets with higher functions, such as architectural similarity, cell-to-cell contact, and the production method. The actual transplantation of naked or encapsulated pseudoislets and islet-like cell clusters from various stem cell sources is also discussed. Advancing our understanding of the methods used to reconstitute pseudoislets should expand the range of potential strategies available for developing de novo islets for therapeutic applications.

Differentiation of human-induced pluripotent stem cells into insulin-producing clusters

OBJECTIVES

In diabetes mellitus type 1, beta cells are mostly destroyed; while in diabetes mellitus type 2, beta cells are reduced by 40% to 60%. We hope that soon, stem cells can be used in diabetes therapy via pancreatic beta cell replacement. Induced pluripotent stem cells are a kind of stem cell taken from an adult somatic cell by "stimulating" certain genes. These induced pluripotent stem cells may be a promising source of cell therapy. This study sought to produce isletlike clusters of insulin-producing cells taken from induced pluripotent stem cells.

MATERIALS AND METHODS

A human-induced pluripotent stem cell line was induced into isletlike clusters via a 4-step protocol, by adding insulin, transferrin, and selenium (ITS), N2, B27, fibroblast growth factor, and nicotinamide. During differentiation, expression of pancreatic β-cell genes was evaluated by reverse transcriptase-polymerase chain reaction; the morphologic changes of induced pluripotent stem cells toward isletlike clusters were observed by a light microscope. Dithizone staining was used to stain these isletlike clusters. Insulin produced by these clusters was evaluated by radio immunosorbent assay, and the secretion capacity was analyzed with a glucose challenge test.

RESULTS

Differentiation was evaluated by analyzing the morphology, dithizone staining, real-time quantitative polymerase chain reaction, and immunocytochemistry. Gene expression of insulin, glucagon, PDX1, NGN3, PAX4, PAX6, NKX6.1, KIR6.2, and GLUT2 were documented by analyzing real-time quantitative polymerase chain reaction. Dithizone-stained cellular clusters were observed after 23 days. The isletlike clusters significantly produced insulin. The isletlike clusters could increase insulin secretion after a glucose challenge test.

CONCLUSIONS

This work provides a model for studying the differentiation of human-induced pluripotent stem cells to insulin-producing cells.

Diabetes treatment: A rapid review of the current and future scope of stem cell research

Diabetes mellitus is a major health concern of the developing and developed nations across the globe. This devastating disease accounts for the 5% deaths around the world annually. The current treatment methods do not address the underlying causes of the disease and have severe limitations. Stem cells are unique cells with the potential to differentiate into any type of specialized cells. This feature of both adult and embryonic stem cells was explored in great detail by the scientists around the world and are successful in producing insulin secreting cells. The different type of stem cells (induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs) and adult stem cells) proves to be potent in treating diabetes with certain limitations. This article precisely reviews the resources and progress made in the field of stem cell research for diabetic treatment.

Regulation of Stem Cell Fate in a Three-Dimensional Micropatterned Dual-Crosslinked Hydrogel System

Micropatterning technology is a powerful tool for controlling the cellular microenvironment and investigating the effects of physical parameters on cell behaviors, such as migration, proliferation, apoptosis, and differentiation. Although there have been significant developments in regulating the spatial and temporal distribution of physical properties in various materials, little is known about the role of the size of micropatterned regions of hydrogels with different crosslinking densities on the response of encapsulated cells. In this study, novel alginate hydrogel system is engineered that can be micropatterned three-dimensionally to create regions that are crosslinked by a single mechanism or dual mechanisms. By manipulating micropattern size while keeping the overall ratio of single- to dual-crosslinked hydrogel volume constant, the physical properties of the micropatterned alginate hydrogels are spatially tunable. When human adipose-derived stem cells (hASCs) are photoencapsulated within micropatterned hydrogels, their proliferation rate is a function of micropattern size. Additionally, micropattern size dictates the extent of osteogenic and chondrogenic differentiation of photoencapsulated hASC. The size of 3D micropatterned physical properties in this new hydrogel system introduces a new design parameter for regulating various cellular behaviors, and this dual-crosslinked hydrogel system provides a new platform for studying proliferation and differentiation of stem cells in a spatially controlled manner for tissue engineering and regenerative medicine applications.

The use of stem cells for pancreatic regeneration in diabetes mellitus

The endocrine pancreas represents an interesting arena for regenerative medicine and cell therapeutics. One of the major pancreatic diseases, diabetes mellitus is a metabolic disorder caused by having an insufficient number of insulin-producing β cells. Replenishment of β cells by cell transplantation can restore normal metabolic control. The shortage in donor pancreata has meant that the demand for transplantable β cells has outstripped the supply, which could be met by using alternative sources of stem cells. This situation has opened up new areas of research, such as cellular reprogramming and in vivo β-cell regeneration. Pluripotent stem cells seem to be the best option for clinical applications of β-cell regeneration in the near future, as these cells have been demonstrated to represent an unlimited source of functional β cells. Although compelling evidence shows that the adult pancreas retains regenerative capacity, it remains unclear whether this organ contains stem cells. Alternatively, specialized cell types within or outside the pancreas retain plasticity in proliferation and differentiation. Cellular reprogramming or transdifferentiation of exocrine cells or other types of endocrine cells in the pancreas could provide a long-term solution.

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.

Use of Mesenchymal Stem Cell-Conditioned Medium to Activate Islets in Preservation Solution

Pancreatic islet transplantation has received widespread attention as a promising treatment for type 1 diabetes. However, islets for transplantation are subject to damage from a number of sources, including ischemic injury during removal and delivery of the donor pancreas, enzymatic digestion during islet isolation, and reperfusion injury after transplantation in the recipient. Here we found that protein fractions secreted by mesenchymal stem cells (MSCs) were capable of activating preserved islets. A conditioned medium from the supernatant obtained by culturing adipose tissue MSCs (derived from wild-type Lewis rats) was prepared for 2 days in serum-free medium. Luc-Tg rat islets to which an organ preservation solution was added were then incubated at 4°C with fractions of various molecular weights prepared from the conditioned medium. Under the treatment with some of the fractions, by 4 days the relative luminescence intensities (representative of the ATP levels of the cold-preserved islets) had increased to over 150% of their initial values. Our novel system may be able to restore isolated islets to the condition they were in before transport, culture, and transplantation.

In-vitro generation of human adipose tissue derived insulin secreting cells: up-regulation of Pax-6, Ipf-1 and Isl-1

We present a study of up-regulation of genes responsible for pancreatic development in glucose-sensitive insulin-secreting mesenchymal stem cells (IS-MSC) generated and differentiated from human adipose tissue (h-AD), with use of our specific differentiation media and without use of any xenogenic material. Anterior wall abdominal fat was collected from 56 volunteers and cultured in self-designed proliferation medium for 10 days. Cells were harvested by trypsinization and differentiated into insulin-expressing cells using self-designed differentiation medium for 3 days followed by evaluation for transcriptional factors Pax-6, Ipf-1, Isl-1, C-peptide and insulin secretion. Generated IS-MSC showed expression of Pax-6, Pdx-6 and Isl-1. Non-differentiated MSC as well as their further culture in absence of differentiation medium were used as negative controls. Generated 56 IS-MSC cell-lines were glucose responsive i.e. mean C-Peptide and insulin secretion levels were measured 0.41 ng/ml and 13.13 μU/ml, respectively, in absence of glucose which rose to 1.18 ng/ml and 83.42 μU/ml, respectively, following glucose challenge (p < 0.001). The mean rise in C-peptide and insulin secretion levels was 2.88 and 6.35 fold, respectively. To conclude insulin-secreting h-AD-MSC can be generated safely and effectively with application of specific differentiation media without xenogeneic material/any genetic modification, showing expression of transcriptional factors Pax-6, Ipf-1 and Isl-1.

Extrinsic factors promoting in vitro differentiation of insulin-secreting cells from human adipose tissue-derived mesenchymal stem cells

Understanding of β cell regeneration is needed to develop new treatment modalities in diabetes mellitus. We present our experience of glucose-sensitive insulin-secreting mesenchymal stem cells (IS-MSC) generated and differentiated from human adipose tissue (h-AD) with application of specific differentiation media, sans xenogenic material. h-AD from donor abdominal wall was collected in proliferation medium composed of α-Minimum Essential Media, albumin, fibroblast-growth factor and antibiotics, minced, incubated in collagenase I at 37 °C with shaker and centrifuged. Supernatant and pellets were separately cultured in proliferation medium on cell + plates at 37 °C with 5 % CO(2) for 10 days. Cells were harvested, checked for viability, sterility, quantification, flow-cytometry (CD45(-)/90(+)/73(+)), and differentiated into insulin-expressing cells using medium composed of Dulbecco's modified eagle's medium, gene expressing upregulators and antibiotics for 3 days. They were studied for transcriptional factors paired box genes-6(Pax-6), islet 1 transcriptional factor (Isl-1), pancreatic and duodenal homobox-1(Pdx-1). C-peptide and insulin were measured by chemiluminescence. IS-MSC showed presence of all three transcriptional factors and showed rise in insulin and c-peptide level in presence of glucose stimuli. It can be concluded that the specific extrinsic factors used in the defined differentiation media effectively and safely promote differentiation of glucose-sensitive insulin-secreting cells from human adipose tissue, without any genetic modulation.

GLP-1 could improve the similarity of IPCs and pancreatic beta cells in cellular ultrastructure and function

Transplantation of functional insulin-producing cells (IPCs) provides a novel mode for insulin replacement, but is often accompanied by many undesirable side effects. Our previous studies suggested that IPCs could not mimic the physiological regulation of insulin secretion performed by pancreatic beta cells. To obtain a better method through which to acquire more similar IPCs, we compared the difference between IPCs of the GLP-1 group and IPCs of the non-GLP-1 group in the morphological features in cellular level and physiological function. The levels of insulin secretion were measured by ELISA. The insulin and glucagon-like peptide-1 (GLP-1) mRNA gene expression was determined by real-time quantitative PCR. The morphological features were detected by atomic force microscopy (AFM) and laser confocal scanning microscopy (LCSM). Intracellular Ca(2+) levels and Glucagon-like peptide-1 receptor (GLP-1R) levels were determined by flow cytometer (FCM). We found that IPCs of the GLP-1 group had bigger membrane particle size and average roughness (Ra ) than IPCs of the non-GLP-1 group but still smaller than normal human pancreatic beta cells. The physiology function of IPCs of the GLP-1 group were much closer to normal human pancreatic beta cells than IPCs of the non-GLP-1 group. GLP-1 could improve the similarity of IPCs from human adipose tissue-derived mesenchymal stem cells and pancreatic beta cells in cellular ultrastructure and function.

Functional evaluation of ES cell-derived endodermal populations reveals differences between Nodal and Activin A-guided differentiation

Embryonic stem (ES) cells hold great promise with respect to their potential to be differentiated into desired cell types. Of interest are organs derived from the definitive endoderm, such as the pancreas and liver, and animal studies have revealed an essential role for Nodal in development of the definitive endoderm. Activin A is a related TGFβ member that acts through many of the same downstream signaling effectors as Nodal and is thought to mimic Nodal activity. Detailed characterization of ES cell-derived endodermal cell types by gene expression analysis in vitro and functional analysis in vivo reveal that, despite their similarity in gene expression, Nodal and Activin-derived endodermal cells exhibit a distinct difference in functional competence following transplantation into the developing mouse embryo. Pdx1-expressing cells arising from the respective endoderm populations exhibit extended differences in their competence to mature into insulin/c-peptide-expressing cells in vivo. Our findings underscore the importance of functional cell-type evaluation during stepwise differentiation of stem cells.

Generating insulin-producing cells for diabetic therapy: existing strategies and new development

Type 1 and 2 diabetes are characterized by a deficiency in β-cell mass, which cannot be reversed with existing therapeutic strategies. Therefore, restoration of the endogenous insulin-producing cell mass holds great promise for curing diabetes in the future. Since the initial induction of insulin-producing cells (IPCs) from embryonic stem (ES) cells in 1999, several strategies and alternative cell sources have been developed to generate β-like cells, including direct differentiation from ES cells or induced pluripotent stem (iPS) cells, proliferation of existing adult β-cells, and reprogramming of non-pancreatic adult stem/mature cells or pancreatic non-β-cells to β-like-cells. However, several barriers persist in the translation of the aforementioned strategies into clinically applicable methods for IPC induction. We briefly review the most relevant studies for each strategy, and discuss the comparative merits and drawbacks. We propose that ex vivo patient-specific IPCs generated from iPS cells may be practical for cell transplantation in the near future, and in situ regeneration of IPCs from cells within the pancreas may be preferable for diabetes therapy.