Exosomes as a novel pathway for regulating development and diseases of the skin.

Exosomes are one of the most potent intercellular communicators, which are able to communicate with adjacent or distant cells. Exosomes deliver various bioactive molecules, including membrane receptors, proteins, mRNA and microRNA, to target cells and serve roles. Recent studies have demonstrated that exosomes may regulate the functions and diseases of the skin, which is the largest organ of the human body. The abnormal functions of the skin lead to the progression of scleroderma, melanoma, baldness and other diseases. A previous study has demonstrated that epithelial progenitor cells are rich in several subunits of exosomes that may maintain the proliferative capacity of these epithelial progenitor cells, which is essential for the development of the epidermis. Exosomes derived from human adipose mesenchymal stem cells accelerate skin wound healing by optimizing fibroblast properties; this is beneficial for the recovery of postoperative and other wounds. Exosomes derived from adipocytes promote melanoma migration and invasion through fatty acid oxidation; therefore, in the clinic, it may be possible to improve the prognosis of patients with melanoma by reducing their body fat content. Exosomes derived from keratinocytes modulate melanocyte pigmentation, which has been utilized as a novel mechanism for the regulation of pigmentation in conditions including Moynahan syndrome and albinism. Meanwhile, scleroderma patients with vascular abnormalities may experience decreased serum exosome levels; it may therefore be possible to detect the exosome content in sera in order to diagnose and treat scleroderma. In addition, the use of exosomes has been suggested to promote or enhance hair growth, which has been demonstrated to be highly effective. These studies have provided new opportunities and therapeutic strategies for understanding how exosomes regulate intercellular communication in pathological processes of the skin.