Adult Stem Cells for Treatment of Oa in the Dog: Data to and from the Clinic

Adult stem cells in veterinary medicine can be derived from adipose tissue or from bone marrow. In small animal veterinary medicine stem cells are more commonly collected from adipose tissue but my opinion is that bone marrow-derived cells remain a perfectly reasonable option. There are key species differences and this is one difference between the canine and equine world. In horses, adult stem cells are usually collected from bone marrow because it can be performed in the standing horse and the BM provides a better source of cells than fat. In dogs, adipose-derived stem cells (ASC) are usually collected from the falciform ligament but can also be collected from any fat deposit such as just caudal to the shoulder or from the inguinal region. Although the data is not definitive; recent investigations have suggested that cell harvest from the falciform ligament generally yields the largest, most predictable amount of cells. Adiposederived cells appear to have a similar potential for differentiation into bone, cartilage, adipose, and fibrous tissues as bone marrow derived cells. This multipotency is a key component to calling a cell a “stem cell” and is something we, and others, have been able to demonstrate from fat and BM derived cells in the dog and horse. Adipose-derived stem cells hold great potential for the treatment of many conditions in the dog because of their trophic and anti-inflammatory properties and because they can differentiate into several other cell lines. The most notable tissues that adult stem cells can form is bone and cartilage. Because of this the main focus in the veterinary literature has been the treatment of osteoarthritis (OA). In two, prospective, randomized, placebo-controlled studies, dogs with lameness from osteoarthritis improved as compared to dogs treated with placebo. However, the strength of this evidence should be considered as the number of dogs evaluated was small and only subjective outcome measures (owner and veterinarian opinion) were used. Data in other species would suggest that ASCs could be used for bone and ligament injuries, spinal cord injury, cardiomyopathies, and inflammatory conditions of the gastrointestinal tract and skin. Certainly, many empirical stories are available for these types of conditions. In addition, the potential to gain valuable information from naturally occurring animal diseases in order to translate it to the human field is immeasurable. Currently, for veterinary use, ASCs are isolated by collagenase digestion of adipose tissue that yields an initial stromal vascular fraction (SVF) that can be further processed by cell culture. Historically, stem cell therapy in dogs has been limited to commercial operations (e.g. Vet Stem) that will process fat obtained from a patient, and return a stromal vascular fraction (SVF) preparation of stem cells to the veterinarian for injection. Stem cells are not specifically isolated or cultured. This process is time intensive, requiring a veterinarian specifically trained (this is an online training process via Vet Stem) in proper handling of the care and acquirement of tissue. However, systems are now available that allow this processing to be performed directly in the veterinary clinic with little training. While this adds convenience and reduces time and cost it introduces error and variability in the product (SVF). Thus the patient, with systemic illness, must undergo a general anesthetic episode for surgical collection of fat. Significant cost can be incurred by the owner for the surgical procedure and the process of preparing the SVF from the fat. Although this process is far from perfect it is what is currently available. The SVF has many limitations. First, it is important to understand that this “treatment” includes all