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Priors Farm can offer the latest advances in the treatment of joint and tendon disease using autologus condition serum therapies (STEM CELLS, IRAP and PRP).


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.

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.


IRAP (Interleukin-1 (IL-1) Receptor Antagonist Protein) has been developed for the treatment of joint disease. The process uses the horse’s own serum to combat osteoarthritis in the joint. IL-1 is a cytokine secreted by cells of the immune system to attack infections and damaged or dying cells. Although this is an important part of the inflammatory response, it can be detrimental to joints by accelerating deterioration of the cartilage. IRAP works by blocking IL-1 from binding to tissues and as a result preventing the damage to the cartilage. Therefore the reason IRAP is exciting is its potential long-term effect on cartilage i.e. preventing an injured joint becoming an arthritic joint.

The procedure starts with sterile collection of blood into a syringe with special glass beads that stimulate production of IL-1. After incubation and centrifuging the IRAP rich serum is injected into the affected joint in a sterile manner. Usually IRAP treatments are given on three occasions at two week intervals. Case selection is very important and IRAP is of most benefit in joint disease where no x-ray change can be seen but pain has been localised exclusively to the joint. In these cases we have found IRAP to be remarkably effective with horses returning to normal work. In addition we have also seen benefits in its use where there is a damaged ligament associated with a joint for example with coffin joint collateral ligament injuries. It is however no substitute for surgery where fragments must be taken out, and there are also limitations in its use for the later stages of joint disease.


Platelet rich plasma is a new therapy for the treatment of equine tendon and ligament injuries. It is a welcome addition to the range of therapies available to treat these injuries because it offers an affordable, practical and scientifically based point of care treatment alternative to horse owners and trainers alike.

Horses suffering tendon and ligament injuries have historically had a poor prognosis for a return to athletic ability due to the limited ability of tendons to repair after injury. The repair tissue is often functionally inferior to normal tendon tissue and this goes hand in hand with an increased risk of re-injury. In the normal, uninjured tendon, there is an abundance of type 1 collagen. After injury, tendons tend to repair with an abundance of type 4 collagen. Type 1 collagen is preferable to type 4 because it is made up of long fibres with few cross links. In contrast, type 4 collagen is made up of short fibres with many cross links. These short type 4 fibres do not move as independently as long type 1 fibres and are therefore much more susceptible to re-injury.

Platelets are found in abundance in the blood stream and are mostly known for the role they play in blood clotting. However, platelets are not just involved in blood clotting, but are in fact an integral part of the early repair process at the site of any injury. When platelets organise into a clot, they release a variety of growth factors that are important for the repair of injured tissue. Platelets also send signals to other cells within the body to move to the site of injury. The clot also acts as a scaffold to retain the growth factors at the site of injury.

Growth factors released by platelets include: Transforming growth factor Β, Platelet derived growth factor, vascular endothelial growth factor and Insulin Like growth factor. Vascular endothelial growth factor has been shown to be an important factor involved in the proliferation and remodelling of tenocytes (tendon cells). Studies have also demonstrated that Transforming growth factor, platelet derived growth factor and vascular endothelial growth factor act together to accelerate white blood cell infiltration of the injury and stimulate new blood supply to the injured tenocytes. This is a very beneficial characteristic because one of the major limiting factors for tendon regeneration is a poor blood supply to the injured tissue.

Importantly, a study using Platelet rich plasma on equine tendons showed that tendons cultured in 100% Platelet rich plasma solution showed an increase in the expression of collagen Type 1 producing cells. Based on our current understanding of the repair process occurring after tendon injury, platelet rich plasma appears to be very beneficial in the regeneration of new tendon fibres and indeed this technology has been used in human medicine for some time.

The collection and preparation of platelet rich plasma is simple, non-invasive and takes only about 30 minutes. Firstly, 60mls of venous blood is collected from the horses’ jugular vein. The blood is transferred to a holding device, which is then placed into a portable centrifuge and spun for 3 minutes. This process separates the serum from the red blood cells. The serum is removed from this sample, placed into the centrifuge and spun for a further 15 minutes. This process leaves the platelets concentrated at the bottom of the sample. Excess serum is then removed and the platelets are re-suspended and ready for injection into the injured tendon. The injured horse is mildly sedated and a nerve block is administered to anaesthetise the injured area. The platelet rich plasma is then injected back into the injured tendon under ultrasound guidance.

After implantation of platelet rich plasma into the injured area, the horse is then confined for a period of 2-3 weeks, with the leg bandaged at all times. We prefer to not administer any anti-inflammatories after implantation because of the possibility that anti-inflammatories may interfere with the cellular response to platelet rich plasma therapy. After the initial 2-3 week period, horses are confined for a further period of 6 weeks in a small yard. After this time a gradual exercise program is commenced with the aim of returning to horse to full activity over a period of 6-12 months depending on the degree of injury and ligament injured. We recommend repeat ultrasound examinations of the injured tendon at one, four and six months post injury to facilitate assessment of the healing process and allow tailored modifications to the controlled exercise program.