Mesenchymal Stem Cell Treatment of Osteoarthritis

Kenneth A. Johnson, Editor-in-Chief Treatment of canine osteoarthritis comprises a large part of the clinical practice of small animal surgeons. Some cases are post-traumatic, but most are heritable, developmental or idiopathic in origin. Although the pathological changes of osteoarthritic joints are essentially irreversible, many types of surgical procedures are aimed at restoring mobility, including prosthetic joint replacement, joint resurfacing, osteotomy, arthrodesis and excision arthroplasty. However, for a very large cohort of dogs suffering from osteoarthritis, surgical treatment of osteoarthritis is not indicated, not appropriate, not feasible or not affordable. Consequently, the search for effective non-surgical treatments such as systemic and intra-articular medications and other modalities is a critical priority. Considering that intractably painful osteoarthritis is a frequent reason for poor quality of life and even euthanasia, this is indeed an appropriate priority. Innumerable medication and therapies have been administered to dogs suffering from osteoarthritis; most recently, the interest has been focused on gene therapy, cytokine inhibition, plasma rich proteins and mesenchymal stem cells. Stem cell therapy is currently being offered by many veterinary clinical programmes for the treatment of osteoarthritis and other diseases including neoplasia. A recent PubMed search using the term ‘mesenchymal stem cell’ yielded 56,877 hits, while ‘mesenchymal stem cell + osteoarthritis’ gave 1,183 citations. However, ‘mesenchymal stem cell + osteoarthritis + dog’ found a meagre 34 citations, of which only about half were in peer-reviewed journals. Since it would appear that the clinical use of mesenchymal stem cells in veterinary practice is galloping ahead of the published research, the study published in this issue of the journal is a welcome addition to the scientific literature. Olsen and colleagues found that intravenously administered allogeneic mesenchymal stem cells were well tolerated by dogs with elbow osteoarthritis. While some subjective outcome evaluations found significant improvements with this treatment, a raft of different objective outcome measures failed to demonstrate any significant improvement. Although this is somewhat disappointing from a clinical stand point, these data are very valuable because they provide important knowledge on which further blinded clinical studies can be planned in future.