Immunological safety assessment of a single and repeated intra-articular administration of xenogeneic equine umbilical cord mesenchymal stem cells under field conditions in young healthy dogs: A randomized double-blind placebo-controlled study

The objective was to study the cellular immune response of equine umbilical cord mesenchymal stem cells (EUC-MSCs) in healthy dogs after a single and repeated intra-articular administration versus placebo in the right knee. Sixteen dogs were randomized into two groups of eight dogs that received two intraarticular administrations of placebo or EUC-MSCs on day 0 and on day 28. Blood samples for the analysis of cellular response were obtained from the cephalic vein on days 0 for baseline data, 14, 28 (before the second administration), 42, and 56. A cellular response assay was made through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT tetrazolium) method. No cytotoxic reaction occurred between lymphocytes and EUC-MSC demonstrating the safety of EUCMSCs administration in dogs. Overall these results suggest that the administration of EUC-MSCs can be considered as safe.