Mesenchymal stem cells in veterinary clinical practice: Evidence from naturally occurring diseases

Over the past two decades, the use of mesenchymal stem cells (MSCs) in veterinary medicine has expanded rapidly, although the clinical evidence remains in its early stages. This review discusses clinical studies involving client-owned animals with naturally occurring diseases in which MSCs or MSC-derived extracellular vesicles (EVs) were used as treatments. It covers musculoskeletal disorders, including osteoarthritis, tendon and ligament injuries, and bone diseases; soft-tissue and oral mucosal conditions; neurological disorders; ophthalmic diseases; and internal medicine disorders, such as inflammatory bowel disease, chronic kidney disease, and respiratory diseases. The most robust data are available for equine superficial digital flexor tendon injuries and osteoarthritis in dogs and horses, with several controlled or prospective studies. For other conditions, evidence is mostly from pilot studies, case series, or single trials. The application of MSC-derived EVs in veterinary medicine is still very new, with preclinical results far exceeding clinical validation. Variations in cell source, preparation, dosing, routes of administration, and outcome measures across studies hinder direct comparisons and meta-analyses. This review offers a critical assessment of current evidence, highlights ongoing gaps, and suggests future directions to improve the translational potential of MSC therapies in veterinary care.