Regenerative Medicine for Equine Musculoskeletal Diseases

Abstract

Musculoskeletal injuries and chronic degenerative diseases commonly affect both athletic and sedentary horses and can entail the end of their athletic careers. The ensuing repair processes frequently do not yield fully functional regeneration of the injured tissues but biomechanically inferior scar or replacement tissue, causing high reinjury rates, degenerative disease progression and chronic morbidity. Regenerative medicine is an emerging, rapidly evolving branch of translational medicine that aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. It includes tissue engineering but also cell-based and cell-free stimulation of endogenous self-repair mechanisms. Some regenerative medicine therapies have made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising results. However, the qualitative and quantitative spatiotemporal requirements for specific bioactive factors to trigger tissue regeneration in the injury response are still unknown, and consequently, therapeutic approaches and treatment results are diverse. To exploit the full potential of this burgeoning field of medicine, further research will be required and is ongoing. This review summarises the current knowledge of commonly used regenerative medicine treatments in equine patients and critically discusses their use.

Case Report: Repeated Intralesional Injections of Autologous Mesenchymal Stem Cells Combined With Platelet-Rich Plasma for Superficial Digital Flexor Tendon Healing in a Show Jumping Horse

“…Superficial digital flexor tendon (SDFT) injuries are a severe problem that affect a large percentage of athletic and pleasure horses; often they develop recidivisms and, in the worst scenario, have to retire from competition early (9,47). In a One Health perspective, the equine could play an important role as a model for human musculoskeletal disorders because of their similarities (48)(49)(50), especially for investigating the regenerative efficacies of innovative treatments such as PRP, bone marrow aspirate (BMA), or MSCs.…”

“…Tendinopathies are one of the most common orthopedic disorders in equine and human athletes, leading to lameness and pain (1)(2)(3)(4)(5). Tendon injuries are responsible for approximately one third of traumas that occur during the sporting career of horses (6,7), forcing a significant number of individuals to an early retirement from competition (8,9). The superficial digital flexor tendon (SDFT) is frequently injured in show jumping discipline due to the repeated and excessive loading forces that the tendon has to sustain after jumping and landing (10,11).…”

“…Tendons possess a limited regenerative capacity and usually heal by forming a fibrotic scar, but the repaired tissue possesses inferior biomechanical characteristics compared to its normal physiological counterpart (13)(14)(15). Consequently, horses that have previously sustained a tendon injury are more prone to re-injury (up to 80%) or to chronicity (9,16).…”

“…Another product of interest in equine regenerative practice is platelet-rich plasma (PRP), a blood-derived product rich in growth factors and cytokines that can sustain and boost the tissue healing process (20,27,28). When combined, these two treatments possess a higher regenerative potential in comparison to their application alone as it has been demonstrated for treating different tissue (e.g., skin, bone, joint) in human and horses (9,(29)(30)(31)(32)(33). Nevertheless, only one study describes the repeated application of MSCs and PRP for the treatment of naturally occurring chronic tendonitis, which was not a re-injury, in the equine in a 16-weeks time interval (34).…”

Role of Innate Immunity in Initiation and Progression of Osteoarthritis, with Emphasis on Horses

“…McIlwraith et al reported the direct and indirect medical costs associated with OA to be between $3000–15,000 per horse each year in the U.S. alone [ 5 ]. Specific populations of horses may also suffer from higher rates of OA, with up to 66% of Thoroughbred racehorses developing this disorder, resulting in pain and significantly shortened career-spans [ 6 , 7 ].…”