Meddleton Equine Hospital

Adult (mesenchymal as opposed to embryonic) stem cells are primitive, non-differentiated cells that are located in the bone marrow, adipose (fat) tissue, and the circulatory system. They are part of the bodies repair system, and are able to transform into nearly any type of cell in the body. When normal tissue is diseased or injured, these stem cells are signaled to migrate to the area of damage. There, under the influence of the local growth factors and signals, these stem cells will differentiate into whatever cell type is needed to help regenerate the normal architecture of the tissue. With this in mind, stem cells have been used to treat tendon and ligament tears, muscle injuries, bone cysts, bone fractures, OCD, arthritis, and even heart muscle damage. Its primary use in the horse has been with tendon and ligament injuries.

Using Stem Cell Therapy in torn tendons or ligaments significantly improves the outcome. The stem cells differentiate into tendon or ligament cells, thus healing the injury with tendon cells in tendons or ligament cells in ligaments thus delivering site appropriate regeneration without scarring. When these areas heal with scar tissue, they never heal as strong or as elastic as the original structure, are more prone to re-injury, and heal very slowly. In some cases they may never heal completely. Using stem cell therapy can dramatically improve the quality and rate of healing, reduce the time off and the likelihood of re-injury, and help get your horse back to your previous level of work.

There are currently three methods of Stem Cell Therapy

1. Bone Marrow derived stem cells:
   • This was the original method of obtaining stem cells. Stem cells along with growth factors are harvested from the sternum or pelvis of the horse through a large bore bone marrow needle and then injected into the site of injury. This requires careful placement of the needle in the sternum or ilium. Once the bone marrow is collected it can be injected directly into the injured site. This has been shown to be quite successful for many different types of injuries.
   • The stem cells can be sent out to be cultured and multiplied over several weeks to increase the numbers of actual stem cells that are injected back into the injured tissue. Although very expensive, this is probably the best method.
2. Fat derived stem cell:
   • Vet-Stem claims that there is a relatively high concentration of stem cells stored in adipose tissue. This has been disputed and remains to be clarified, however, success rates have been promising.
   • Harvesting fat tissue requires sedation and local anesthesia to surgically remove a small amount of fat (approximately 2 tablespoons) which is then shipped to a Lab in California to be processed and purified, then shipped back to be implanted in the affected area. This usually requires 48-72 hours.
3. ACell Therapy:
   • ACell is a product derived from a naturally occurring biological source. It is a derivation of the extracellular matrix of porcine urinary bladder. It adheres to damaged tissue, forms a scaffold, and recruits fibroblasts and adult stem cells from the local tissues and the circulatory system.
   • This is a less invasive and less expensive way to treat tendons and ligament injuries, and can be done on the farm. A recent study, including 101 tendon or ligament injuries treated with ACell, showed approximately 80% return to the previous level of use.