Stem Cell Therapy
Mesenchymal stem cells are undifferentiated cells that exist in the bone marrow. These cells have the potential for unlimited replication. They also have the ability to differentiate into different types of cells in response to their local environment.
The aim of delivering mesenchymal stem cells to the site of a tendon or ligament injury is to supply cells that can differentiate into collagen producing cells and thus have a favourable effect on tissue organization and composition. Mesenchymal stem cells have been used in equine medicine to treat superficial and deep digital flexor tendon lesions, check ligament lesions, suspensory ligament lesions and lesions of the straight sesamoidean ligament.
At Tweedie and Associates, we currently have two techniques available to treat tendon and ligament injuries with bone marrow derived mesenchymal stem cells. The first involves direct injection of raw bone marrow aspirate. The second involves aspiration of bone marrow, culture of the cell population derived from bone marrow aspirate and implantation of this cultured cell population into the lesion at a later date.
Both procedures involve collecting bone marrow from the horses’ sternum. The horse is sedated and a local anaesthetic is administered approximately where the center of the girth would sit if the horse were saddled. Ultrasound is used to locate the exact position of the sternum. The sternum and the injured tendon are then prepared in a sterile fashion. A bone marrow biopsy needle is used to aspirate 20-30ml of bone marrow. If raw bone marrow aspirate is to be injected into the lesion it will be injected immediately into the injured area.
In addition to stem cells, bone marrow contains many useful elements for tendon and ligament healing including growth factors such as transforming growth factor and vascular endothelial growth factor. Growth factors can stimulate the division of existing cells, up-regulate collagen production and aid in the regeneration of new capillary blood vessels.
It should be noted that one of the disadvantages associated with injecting raw bone marrow straight into an injured tendon is the small number of mesenchymal stem cells in the aspirate. Another disadvantage is the large volume that needs to be injected into the area and the impact this might have on surrounding, normal tissues. In addition, there has been some concern about the potential for mineralization in tendons treated with bone marrow aspirate.
However, the advantages associated with this procedure are the ability to perform the procedure in a timely fashion and the relatively low cost associated with this therapy. Despite the disadvantages, we have had good success treating tendon and ligament injuries with bone marrow aspiration and injection.
If the bone marrow derived mesenchymal stem cells are going to be cultured prior to injection into the injured area, the aspirated bone marrow is shipped to the laboratory immediately after aspiration. The stem cells are then available for injection approximately three weeks after aspiration of the bone marrow.
The advantage of culturing the cell population for a period of two to three weeks before implantation is that more than 10 x 106 stem cells will be available for injection into the injured area. The cells are suspended in bone marrow supernatant which is rich in growth factors. In addition, because the cells are so concentrated, it is only necessary to inject a volume of 2-3ml into the injured area. These advantages are considerable, however, it should be noted that they are reflected in the increased cost associated with this procedure.
Please do not hesitate to contact our office if you would like to investigate stem cell therapy as a treatment option for your horse. One of our veterinarians will be happy to discuss the costs associated with these procedures and whether or not they would be a suitable treatment for your animal.
