Adipose-derived regenerative cells and secretions for the treatment of canine osteoarthritis

The emergence of cellular therapies in the last fifteen years has seen a paradigm shift in healthcare not only in human medicine but in veterinary medicine also. The use of mesenchymal cells from bone marrow, cord blood or adipose tissue has been used in the treatment of both equine and canine musculoskeletal disorders since the early 2000's. Little is known, however, about the therapeutic mechanisms of these treatments. This thesis documents the cell types and secretion capabilities of adipose-derived therapeutics. It details the evolution of a treatment offering for canine osteoarthritis (OA), from an autologous freshly derived point-of-care treatment to an allogenic culture-expanded off-the-shelf therapeutic. Whilst some characterisation of canine MSCs has occurred in vitro, there is little known about the cell composition and secretion capabilities of the mixed cell population derived from adipose tissue, known as the stromal vascular fraction (SVF). Preliminary in vivo efficacy using the canine SVF was demonstrated in dogs suffering from OA. Whilst historically the differentiation capability of MSCs was thought to be the major driver of therapeutic efficacy, the early treatment response seen in these dogs was far too rapid to be due to tissue regeneration. Furthermore, it is now well established in the literature that the paracrine secretions of MSCs are a key contributing factor to therapeutic effect of these cells. To determine the cell types and composition of the canine SVF and the canine MSCs themselves, an in vitro characterisation utilising cluster differentiation antibodies and flow cytometry was performed. Additionally, the secretion profile of the cell types of the SVF in combination and the MSCs alone was carried out using a multi-plex cytokine analysis approach. This work demonstrated the cells of the SVF secreted therapeutically relevant cytokines and furthermore a correlation between the cells types present and the secretion profile was shown. To further exploit the apparent therapeutic benefit of the cellular secretions, a concentrated cell culture conditioned medium containing the secretions, was added to culture-expanded MSCs. To determine the efficacy of MSCs cryopreserved with cellular secretions, a mouse model of induced arthritis was utilised. The results of this trial showed that the addition of secretions to MSCs had a superior ability as an arthritis-relieving agent to that of MSCs alone. Furthermore, the use of MSCs with secretions was shown to have the same clinical efficacy in canine OA as the freshly derived SVF therapeutic.