Regenerative medicine advances, step by step: "researchers have developed an unlimited number of pure insulin-producing cells from mouse embryonic stem cells (ESCs). ... These pure insulin-producing cells, which according to electron microscopy studies, have the same sub-cellular structures as the insulin-producing cells naturally found in the pancreas, were highly effective in treating diabetes in the mouse model. The transplants of pure insulin-producing cells reduced the blood glucose levels of diabetic mice with high blood glucose levels. ... None of the diabetic mice involved in the transplant experiments developed teratoma, which are a type of tumour often associated with ESCs and which could complicate their use in human therapeutic treatment. Furthermore, the pure insulin-producing cells managed to retain their insulin-production and glucose-sensing capacity over time. ... Besides providing a tool to facilitate basic research in test tubes and animals, these insulin-producing cells may be also used to replace the isolated native pancreatic cells that are hard to obtain in a large amount, for pharmacological tests."