Great advances in type 1 diabetes (T1D) and type 2 diabetes (T2D) treatment have been made to this day. However, modern diabetes therapy based on insulin injections and cadaveric islets transplantation has many disadvantages. That is why researchers are developing new methods to regenerate the pancreatic hormone-producing cells in vitro. The most promising approach is the generation of stem cell-derived beta cells that could provide an unlimited source of insulin-secreting cells. Recent studies provide methods to produce beta-like cell clusters that display glucose-stimulated insulin secretion—one of the key characteristics of the beta cell. However, in comparison with native beta cells, stem cell-derived beta cells do not undergo full functional maturation. In this paper we review the development and current state of various protocols, consider advantages, and propose ways to improve them. We examine molecular pathways, epigenetic modifications, intracellular components, and the microenvironment as a possible leverage to promote beta cell functional maturation. A possibility to create islet organoids from stem cell-derived components, as well as their encapsulation and further transplantation, is also examined. We try to combine modern research on beta cells and their crosstalk to create a holistic overview of developing insulin-secreting systems.

Extracellular vesicles (EVs) are attracting considerable interest due to their important role in cell signaling. However, their nanosized scale, complexity, and heterogeneity make even morphological characterization challenging. Only with the recent advances in cryogenic electron microscopy (cryo-EM), together with the increasing availability of cryo-electron microscopes, has it become possible to visualize the native structure of EVs. In this study we performed an in-depth cryo-EM analysis of EVs derived from four glioblastoma multiforme (GBM) cell lines (U87MG, U373MG, U251MG, and T98G), highlighting the morphological changes induced by temozolomide (TMZ) chemotherapeutic treatment. Size, shape, circularity, concentricity, membrane thickness, and electron density of EVs were analyzed. The key characteristic revealed by cryo-EM was that EVs can be enclosed not only by one membrane bilayer, but also by two or more bilayers (double-layered vesicles, DVs; and multilayered vesicles, MVs). Overall, TMZ treatment substantially modified both the morphology and production of EVs, decreasing the percentage of single-layered vesicles (SVs) while increasing that of DVs and MVs, as well as reducing the electron density of the EV cargo. Morphometric and morphological information can shed light on the contribution of EVs to tumor progression, metabolism, drug resistance, and immune evasion.