By Dr. David Lane, DVM
Regenerative medicine is a new branch of medicine that examines how the body heals itself, then looks for ways to concentrate those efforts where they are most needed. Techniques are rapidly evolving as we learn more, but even though it is early days it is already showing great promise for many treating musculoskeletal conditions that we couldn’t before.
It is particularly useful for alleviating the pain of arthritis, and for growing new tendon or ligament tissue.
Below is a brief overview of the regenerative medicine options available for treating musculoskeletal issues in dogs.
Hyaluronic acid (HA) is a key component of healthy joint fluid and cartilage, and is depleted in arthritic joints, which leads to worsening arthritis, which depletes HA – it’s a self-perpetuating cycle. There are effective oral and subcutaneous injection products that help boost HA levels, but direct injections into the joint are the most effective way to quickly replace HA levels.
HA can be used on its own for early or mild arthritis, or combined with steroids for more advanced and/or painful conditions. It can also be combined with stem cells or PRP (see below). Although we frequently use HA injections for severely arthritic joints, the best effects are seen when it is given earlier in the disease process.
Although HA injections into the joint are helpful, especially when combined with steroids, the effects don’t last as long as they do with PRP injections. There are different steroids that can be used, each with their own pro’s and con’s; the choice of which steroid to use should be matched to your dog’s individual needs.
PRP (platelet rich plasma)
Platelets are the body’s front line soldiers for repairing damaged tissue. They clot the wound to stop bleeding, then release a number of growth factors to initiate the healing process. By collecting a sample of blood from your dog, concentrating down the platelet fraction and then re-injecting this platelet rich plasma (PRP) where it is needed, we see a number of positive effects.
PRP accelerates healing and decreases inflammation associated pain. When injected into arthritic joints, it gives pain relief for 80% of patients (which is the same as either HA or stem cell injections) that lasts about 9 months (which is much longer than HA injections, and almost as much as stem cell injections). The pain relief provided is as good as, if not better, than that provided by combining HA with steroids.
When injected into injured tendons, PRP accelerates repair. I find it very useful for the treatment of many shoulder injuries, including biceps tendon, supraspinatus tendon, and rotator cuff injuries. It can also be used in groin injuries involving the iliopsoas tendon.
Compared to stem cells, PRP is a less invasive and less expensive technique (about 1/3 the cost of stem cell injections). Depending on the joint or tendon being injected, the entire process can happen with only mild sedation, or even no sedation in some dogs. However, for advanced tendon repair, stem cells do a better job.
(Mesenchymal) Stem Cells
Mesenchymal stem cells are very different than embryonic stem cells. We only use mesenchymal stem cells in veterinary medicine. Our bodies constantly undergo some degree of damage and repair, and stem cells are a big part of that repair. They can be found in many tissues, and once stimulated, will begin to grow new healthy tendon, ligament, or bone. They are found in high levels in the marrow and periosteum of bone, and play a big role in fracture repair (along with platelets).
In veterinary medicine, we commonly harvest MSCs from two locations: fat, or bone marrow. Fat derived stem cells are typically sent to an outside lab for processing which often means a second anesthesia for your pet, but bone marrow origin stem cells can be processed and re-implanted immediately as part of the same procedure.
When MSCs were first injected into joints, we were hopeful that they would regrow healthy cartilage and reverse arthritis. Unfortunately, they do not. They do however provide good pain control in most patients for 11 months on average (see PRP above).
However, when injected into damaged tendons, MSCs do regrow normal tissue, as well as resorb scar tissue and mineralization. It is an excellent tool for advanced tendon repair; it is also the treatment of choice for dogs wanting to return to a high level of activity. Stem cells can also be used to accelerate the healing of broken bones.
Regenerative medicine is fast becoming a key tool for addressing and decreasing the progression of arthritic pain and for treating damaged tendons. It is an excellent option for owners who want to avoid daily anti-inflammatories or other prescription medications, or for patients who do not tolerate those medications well.
Most shoulder and groin injuries respond well to rehabilitation medicine (the veterinary equivalent of physiotherapy) but for those that don’t, regenerative medicine is often what is needed for dogs to return to full function.
Case Report: Stem Cell treatment of partially torn biceps tendon.
Biceps tendon injury is a common cause of shoulder pain in dogs. In veterinary medicine, the traditional treatment has been surgical – the tendon is cut from its attachment point so that it is no longer a source of pain. The problem is that once cut, the tendon is no longer a source of stability for the shoulder and now there is an increased change of incurring other secondary shoulder injuries, including rotator cuff tears. SURGICALLY CUTTING THE BICEPS TENDON SHOULD ONLY BE USED AS A LAST RESORT AFTER ALL OTHER TREATMENTS HAVE FAILED!
Rehabilitation therapy offers a new option for treating this condition and is successful in most minor cases where the amount of tendon tearing is not too great. However, if rehabilitation therapy on its own is not enough, PRP or stem cell injections are often what is needed.
This is an ultrasound of a damaged biceps tendon that I examined last summer. Because looking at ultrasound images is a lot like trying to read television static, I’ve added graphics to help. Healthy tendon should have an even level of “whiteness” on ultrasound, with easily distinguished fibers running along its length. Damaged tendon has mixed colouring of light and dark tissue, with disruptions of these fibers.
The two regions coloured blue are the bones of the shoulder joint. See how the tendon crosses from the upper limb on the right to the shoulder blade on the left? By spanning the joint, it provides stability to the shoulder, which is why we want to preserve it if at all possible.
The tendon itself is outlined in red. As you can see, there is quite a bit of colour variation and fibre disruption evident. This is a badly damaged biceps tendon. We tried fixing the tendon using rehabilitation therapy techniques, but it didn’t work. Without some other treatment, this dog would never return to full and pain free activity again.
Here is the same tendon 3 months after injection with stems cells collected from the dog’s bone marrow and injected into the damaged tendon. See the difference? We anticipate that this dog will return to full activity.