Exosomes Derived from Mesenchymal Stem Cells in the Treatment of Animal Tendon Injuries: A Review on Their Isolation and Application

Tendon injuries are a major part of musculoskeletal injuries in animals, particularly in horses. So far, no complete cure has been found for this disease, and most treatments focus on pain control. The advantages of using exosomes over cell-based therapies and the effects of mesenchymal stem cells (MSCs) on tissue repair suggest exosomes derived from MSCs as an appropriate treatment option in repairing tendon injuries. This paper aimed to review various protocols for exosome isolation and the role of MSCs- derived exosomes on tendon tissue repair of animals, especially in horses. In the treatment of tendon disorders, exosomes are more stable than cells, have a lower risk of immune rejection after allogeneic administration, and can be used as an appropriate alternative therapy. Exosomes derived from MSCs of different sources stimulate the proliferation and migration of tenocytes and fibroblasts, mod-ulate collagen fiber arrangement, macrophage functions, and inflammatory responses, inhibit adhesion, and generally repair damaged tendons. Exosomes are involved in cell-cell communication due to the exchange of pro-teins and genetic materials. The use of MSCs-derived exosomes is considered a treatment option due to easier maintenance and reduction of the risk of rejection by the immune system, reducing the possibility of aneuploidy compared to cell-based methods