A Scoping Review of Exosome Delivery Applications in Hair Loss

The objective of this scoping review was to understand the extent and type of evidence found in the current literature on the delivery mechanisms of exosome therapeutics and how these methods can work synergistically with existing treatments for alopecia. Alopecia is primarily characterized as non-scarring or scarring (cicatricial). In cicatricial alopecia, the hair follicles are irreversibly destroyed, causing permanent hair loss. In non-cicatricial alopecia, the hair follicles are undamaged, allowing for possible hair regeneration. Non-scarring alopecia includes androgenetic alopecia, telogen effluvium, and alopecia areata. Current treatments for non-scarring alopecia include oral minoxidil and spironolactone. Exosome therapeutics are a possible alternative treatment for non-scarring alopecia because of their regenerative properties in hair follicle stimulation, customizable size selection, and the potential to activate and down-regulate specific pathways that enhance hair growth. This review evaluates types and sources of exosome delivery as regenerative treatments for alopecia. A search of literature published in English from 2018 to 2023 was performed using the electronic databases EMBASE, Ovid MEDLINE, and Web of Science. Data from selected studies included specific details about the participants, concept, context, study methods, and key findings relevant to the review questions. Upon completion of the database search that yielded 1,087 citations, after removing 284 duplicates, 803 articles remained for assessment of eligibility. Finally, 16 studies were retained for inclusion. These studies explored one or more exosome delivery techniques, such as intradermal needle injection, microneedle patches, topical application, and topical application with a secondary assistive device. The therapeutic focus of these studies ranged from hair follicle regeneration and wound healing to spinal cord injury repair and collagen regeneration for cosmetic purposes. Most of the studies (14 out of 16) used exosomes derived from mesenchymal stem cells (MSCs), while others isolated exosomes from human adipose stem cells, macrophage cell lines, and dermal fibroblast cells. Of the 16 studies, all but two administered exosomes via microneedle patches. The findings suggest that intradermal microneedle patches are a promising method for delivering exosomes into tissues, particularly for the treatment of non-cicatricial alopecia. Exosome therapy shows strong potential for promoting hair follicle regeneration, supported by its proven efficacy in wound healing, spinal cord injury repair, and cosmetic applications. Among the various delivery methods explored, microneedle patches loaded with exosomes from MSCs emerged as the most effective for targeted delivery into tissues. These findings support exosome-based therapies for non-cicatricial alopecia.