The concept of using stem cell therapy as a form of regenerative medicine was born out of a lack of satisfactory therapy for degenerative diseases, such as osteoarthritis. Regenerative medicine also came to the forefront due to a lack of adequate healing of traumatic ailments. These include non-union fractures and tendon and ligament injuries. The goal of stem cell therapy is to initiate tissue regeneration and homeostasis, not just healing. In this way, strength, range of motion and performance are enhanced while minimizing scars, pain, and potentially future related disease.
Stem cells are primitive cells which are present in virtually every tissue. They are capable of differentiating many different tissue types (Figure 1). They are self renewing and act as trophic factories. This allows these adult stem cells to treat traumatic and degenerative diseases, including bowed tendons, ligament injuries, osteoarthritis, and osteochondral defects in horses and dogs.
Figure 1. Differentiation of Adipose into Various Tissues
A key concept is that this type of regenerative medicine utilizes ADULT stem cells. These adult stem cells are derived from adipose tissue from inguinal, caudal scapular or intra-abdominal areas, making them a readily available source, much easier to collect and much more plentiful than those derived from bone marrow. As mentioned above, these cells are able to differentiate into multiple lineages implicating their potential in bone, cartilage, and cardiac repair. Fractions isolated from adipose tissue contain a heterogeneous mixture of regenerative cells, including:
- Mesenchymal stem cells
- Endothelial progenitor cells
- Immune cells
- Other growth factor-secreting bioactive cells
There are multiple advantages of using stem cell regenerative medicine over a more traditional approach. The first is that stem cells do not rely on a single target receptor or a single pathway for their action. They can have very global effects. Additionally, the regenerative cell mixture is delivered either directly to the traumatic wound (e.g. tendonitis, desmitis, fracture) or is delivered systemically (e.g.: liver disease, renal disease). In the case of arthritis, stem cells are injected directly into 2-4 affected joints, or intra-articularly and intravenously to induce a more global effect. Once again the regenerative cells can differentiate into many tissue types, induce repair, and stimulate regeneration. They can also "communicate" with the cells of their local environment through paracrine and autocrine modalities, creating the optimal environment for natural healing. They also produce a variety of both secreted and cell surface substances that regulate tissue growth, integrity, and function.
Figure 2. The Effect of a Single Intra – Articular Injection of Stem Cells on Walking and Trotting Lameness Scores in Dogs with Elbow Osteoarthritis
Currently, over 400 dogs have been treated for osteoarthritis and orthopedic procedures. Most patients had elbow, hip, or knee problems. Initial studies demonstrate that intra-articular administration of regenerative stem cells significantly decreases pain and improves comfort in the majority of cases. Duration of the benefit from a single injection varies from several months to more than one year (Figures 2,3,4). The current indications for regenerative stem cell therapy in dogs includes osteoarthritis and tendon and ligament injuries.
Figure 3. The Effect of Intra-Articular Stem Cells on a Walking Lameness Score in Dogs Hip Osteoarthritis
As more research is conducted, the likelihood of expanding the indications for stem therapy increases. Besides the overwhelming scientific data demonstrating the clinical efficacy of regenerative cellular therapy in animal models of osteoarthritis, osteochondral defects, tendon repair, and fractures, many additional studies demonstrate success in treating systemic disorders such as cerebral and myocardial infarction, muscular dystrophy, and immune-mediated disorders.
Figure 4. The Effect of Intra-Articular Stem Cells on a Trotting Lameness Score in Dogs Hip Osteoarthritis