Influence of a high-fat diet during chronic hyperglycemia on beta-cell function in pancreatic islet transplants to streptozotocin-diabetic rats

Manufacturing clinical-grade human induced pluripotent stem cell-derived beta cells for diabetes treatment

The unlimited proliferative capacity of human pluripotent stem cells (hPSCs) fortifies it as one of the most attractive sources for cell therapy application in diabetes. In the past two decades, vast research efforts have been invested in developing strategies to differentiate hPSCs into clinically suitable insulin‐producing endocrine cells or functional beta cells (β cells). With the end goal being clinical translation, it is critical for hPSCs and insulin‐producing β cells to be derived, handled, stored, maintained and expanded with clinical compliance. This review focuses on the key processes and guidelines for clinical translation of human induced pluripotent stem cell (hiPSC)‐derived β cells for diabetes cell therapy. Here, we discuss the (1) key considerations of manufacturing clinical‐grade hiPSCs, (2) scale‐up and differentiation of clinical‐grade hiPSCs into β cells in clinically compliant conditions and (3) mandatory quality control and product release criteria necessitated by various regulatory bodies to approve the use of the cell‐based products.

Treating diet-induced diabetes and obesity with human embryonic stem cell-derived pancreatic progenitor cells and antidiabetic drugs

Human embryonic stem cell (hESC)-derived pancreatic progenitor cells effectively reverse hyperglycemia in rodent models of type 1 diabetes, but their capacity to treat type 2 diabetes has not been reported. An immunodeficient model of type 2 diabetes was generated by high-fat diet (HFD) feeding in SCID-beige mice. Exposure to HFDs did not impact the maturation of macroencapsulated pancreatic progenitor cells into glucose-responsive insulin-secreting cells following transplantation, and the cell therapy improved glucose tolerance in HFD-fed transplant recipients after 24 weeks. However, since diet-induced hyperglycemia and obesity were not fully ameliorated by transplantation alone, a second cohort of HFD-fed mice was treated with pancreatic progenitor cells combined with one of three antidiabetic drugs. All combination therapies rapidly improved body weight and co-treatment with either sitagliptin or metformin improved hyperglycemia after only 12 weeks. Therefore, a stem cell-based therapy may be effective for treating type 2 diabetes, particularly in combination with antidiabetic drugs.

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High-fat diets (HFDs) caused rapid metabolic dysfunction in immunodeficient mice

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HFDs and/or antidiabetic drugs did not affect function of hESC-derived beta cells

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hESC-derived beta cells improved glucose tolerance in HFD-fed mice

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Cell therapy combined with an antidiabetic drug was the most effective treatment

Islet transplantation in rodents. Do encapsulated islets really work?

CONTEXT

Diabetes mellitus type I affects around 240 million people in the world and only in the USA 7.8% of the population. It has been estimated that the costs of its complications account for 5% to 10% of the total healthcare spending around the world. According to World Health Organization, 300 million people are expected to develop diabetes mellitus by the year 2025. The pancreatic islet transplantation is expected to be less invasive than a pancreas transplant, which is currently the most commonly used approach.

OBJECTIVES

To compare the encapsulated and free islet transplantation in rodents looking at sites of islet implantation, number of injected islets, viability and immunosuppression.

METHODS

A literature search was conducted using MEDLINE/PUBMED and SCIELO with terms about islet transplantation in the rodent from 2000 to 2010. We found 2,636 articles but only 56 articles from 2000 to 2010 were selected.

RESULTS

In these 56 articles used, 34% were encapsulated and 66% were nonencapsulated islets. Analyzing both types of islets transplantation, the majority of the encapsulated islets were implanted into the peritoneal cavity and the nonencapsulated islets into the liver, through the portal vein. In addition, the great advantage of the peritoneal cavity as the site of islet transplantation is its blood supply. Both vascular endothelial cells and vascular endothelial growth factor were used to stimulate angiogenesis of the islet grafts, increasing the vascularization rapidly after implantation. It also has been proven that there is influence of the capsules, since the larger the capsule more chances there are of central necrosis. In some articles, the use of immunosuppression demonstrated to increase the life expectancy of the graft.

CONCLUSION

While significant progress has been made in the islets transplantation field, many obstacles remain to be overcome. Microencapsulation provides a means to transplant islets without immunosuppressive agents and may enable the performance of xenotransplantation. The use of alternative donor sources, fewer islets per capsule and the appropriate deployment location, such as the peritoneal cavity, may give a future perspective to the application of immunoprotective capsules and viability in clinical practice. A variety of strategies, such as genetic engineering, co-encapsulation, improvement in oxygen supply or the establishment of hypoxia resistance will also improve the islet transplantation performance. It remains to be determined which combination of strategies with encapsulation can fulfill the promise of establishing a simple and safe transplantation as a cure for diabetes.

Saturated-fat diet induces moderate diabetes and severe glomerulosclerosis in hamsters

AIMS/HYPOTHESIS

Diets high in saturated fat are thought to be a risk factor for Type 2 diabetes and associated complications. We investigated effects of a medium and high saturated fat diet on the development of diabetes-associated pathologies in Golden Syrian hamsters, an animal that reacts to dietary lipids in a fashion similar to humans.

METHODS

Three diets containing 46.5 kcal %, 267.3 kcal %, and 488.2 kcal % as saturated fat respectively, were studied. Metabolic parameters were measured up to 20 weeks. Electron microscopy was used to examine the structure of the pancreas, aorta and kidney.

RESULTS

Increased saturated fat consumption was associated with: (i) gradual imbalance of homeostasis, and severe structural alterations of acinar, beta cells and capillaries in the pancreas, and of the kidney glomeruli; (ii) severe hypertriglyceridaemia and augmented creatinine concentrations related to disturbances of the renal function, progressing to nodular glomerulosclerosis and nephropathy; (iii) reduced early insulin secretion in response to glucose; (iv) switch of the aortic endothelium to a secretory phenotype.

CONCLUSION/INTERPRETATION

The results show that high-caloric saturated fat intake induced diabetes in hamsters, probably linked to delayed insulin secretion. The model was also associated with the development of a range of pathologies characteristic to human diabetes, including nephropathy and defects in vasculature. Thus, high-fat fed hamsters provide a new model that is likely to be useful in understanding the cellular and molecular mechanisms involved in the pathogenesis of diabetes.