Embryonic stem cell processing in obtaining insulin-producing cells: A technical review

Abstract

Diabetes mellitus derives from the absence of insulin hormone in the organism, usually due to the destruction of insulin-producing pancreatic β-cells either by immune attack or glucolipotoxic mechanisms. Insulin is a key hormone in controlling nutrient (glucose and fatty acids) homeostasis, as well as modulating both their uptake and metabolism by peripheral target tissues, such as skeletal muscle and adipose tissue. Insulin injection can partially mimic endogenous hormone function, although it does not avoid the appearance of secondary complications such as retinopathy, nephropathy, neuropathy, and cardiovascular disorders. Implantation of de novo insulin-producing cells in the organism could be a long-term solution in the treatment of the disease, restoring the lost function. Transplantation of highly pure isolated islets (pancreatic cell clusters where β-cells are located) from cadaveric donors is a possibility, although there are still many problems to resolve, such as immune rejection, low isolation yields, implant survival, and biomaterial scarcity. Altogether, this suggests that alternative sources for insulinproducing cells have to be considered, such as embryonic and adult stem cells. In this context, embryonic stem (ES) cells offer an interesting alternative due to two main properties: self-renewal capability and high differentiation potential. However, during the first culture phases, there are many factors that may affect the amount of differentiated insulin-positive cells obtained following certain protocols. Taking into account those early factors will help to improve present working methods and, consequently, the design of a definite protocol for cell therapy. This review will summarize key practical issues of generating insulin-secreting cells from ES cells based on the experience accumulated by different laboratories, including ours, in this area.