The use of mesenchymal stem cells to treat a wide range of health problems in horses shows considerable promise, the authors of a just-published review conclude.
Alina Cequier and her colleagues, writing in the journal Animals, noted that therapeutics involving mesenchymal stem cells were initially thought to act by differentiating into the cells of the injured tissue.
However, their influence extends further. “These cells are also able to regulate and stimulate the body’s own repair mechanisms, opening the door to many applications in inflammatory and immune-mediated disorders in both animals and humans.
The main target of mesenchymal stem cell therapy in horses has long been the locomotor system, they said, because tendon and joint injuries are common.
But beyond their traditional application in the musculoskeletal system, these cells have been studied for eye-related problems such as corneal ulcers or immune-mediated processes, and for reproductive disorders such as endometritis or endometriosis.
Their potential has been explored for problems in horses very similar to those affecting people, such as asthma, metabolic syndrome, aberrant wound healing, or endotoxemia, as well as for equine-specific pathologies such as laminitis.
“Current evidence is still preliminary, and further research is needed to clarify different aspects, although research performed so far shows the promising potential of mesenchymal stem cells to treat a wide variety of equine pathologies,” the review team, from the University of Zaragoza in Spain, wrote.
Their paper, which examined current knowledge on the use of the cells for equine problems beyond the musculoskeletal system, highlighted the value of the horse as a model for other species.
Eye-related and reproductive disorders are among the most studied areas for use of the cells, they noted.
“Equine asthma, equine metabolic syndrome, and endotoxemia have been less explored but offer an interesting scenario for human translation,” Cequier and her colleagues, Carmen Sanz, Clementina Rodellar and Laura Barrachinam, wrote.
“The use of mesenchymal stem cells in wounds also provides a potential model for humans because of the healing particularities in both species.”
High-burden equine-specific diseases such as laminitis have been suggested to benefit from stem cell therapy, and its use in challenging disorders such as neurologic conditions has been proposed.
However, findings from the use of the cells remain preliminary, and their use requires further development to translate results into the clinic, they said.
“Nevertheless, current evidence indicates a significant potential of equine mesenchymal stem cells to enlarge their range of application, with particular interest in pathologies analogous to human conditions.”
The review team noted shortcomings in some research in the field. These include variability in the clinical cases treated, the source of the mesenchymal stem cells used, cell isolation and culture techniques, and therapeutic protocols (the dose, route of administration, and number and frequency of administration).
There have also been issues around low sample sizes and a lack of control groups in some of the studies.
These limit drawing definitive conclusions, they said.
“Nevertheless, case reports are highly valuable as a proof of concept, indicating that there is potential for further investigations.
Future laboratory studies could provide interesting preliminary insights into mesenchymal stem cell mechanisms for each equine condition being treated, and studies in healthy animals would enable safety and feasibility assessments.
“More in-depth research is needed to test the safety and efficacy of these novel treatments, and future clinical trials would include a larger number of similar cases and standardized measurements of the outcomes, in order to establish specific therapeutic protocols.”
More laboratory and experimental work is needed to understand the pathways through which the cells elicit their effects, in order to achieve their highest therapeutic potential.
“Researchers and clinicians should work together to develop evidence-based treatments and exploit mesenchymal stem cell potential by extending their use to different pathologies in both equine and human patients.”
Cequier, A.; Sanz, C.; Rodellar, C.; Barrachina, L. The Usefulness of Mesenchymal Stem Cells beyond the Musculoskeletal System in Horses. Animals 2021, 11, 931. https://doi.org/10.3390/ani11040931