Exosomes are extracellular vesicles (EVs) secreted from a majority of cell types. Exosomes play a role in healthy and pathogenic intercellular interactions via the transfer of proteins, lipids, and RNA. The contents and effects of exosomes vary depending on the properties of the originating cell. Exosomes secreted from some cell types, including stem cells, carry biological factors implicated in the protection, regeneration, and angiogenesis of damaged tissues. Due to these properties, exosomes have attracted attention as a novel vector for regenerative therapies. Exosomes as a therapeutic tool could have applications for the treatment of many disorders characterized by chronic tissue damage. Exosomes derived from stem cells could be applied to repair or prevent damage from the complications of diabetes mellitus. The immunomodulatory and reparative properties of stem cell-derived exosomes could protect, or even restore an early stage type-1 diabetic patient’s original islets from autoimmune destruction. Exosomes could also possibly suppress graft rejection of pancreatic islet transplants. Researchers from the Roger Williams Medical Center suggest that the treatment of diabetes mellitus using exosome based therapies be further explored. Development of novel therapies using exosomes is slowed by a limited understanding of their mechanisms. This hurdle must be overcome to pave the way for clinical trials and ultimately the adaptation of exosomes as a therapeutic vector.
Mechanisms of Exosome interaction with target cell
Ligands (triangles) on the surface of the exosomal membrane bind to receptors on the target cell. From there, the receptor-ligand interaction can trigger one of the following: (1) fusion of the exosomal membrane with the cell’s plasma membrane, releasing cargo (small circles) into the cytosol, (2) initiation of a downstream signaling cascade in the target cell, (3) endocytosis of the exosome, followed by the fusion of the exosome with the endosome’s membrane, releasing cargo (small circles) into the cytosol.