Microbiological safety assessment of canine adipose derived mesenchymal stem cell preparations reveal no detectable contamination

The experimental application of canine adipose-derived mesenchymal stem/stromal cells (cAD-MSC) has demonstrated excellent therapeutic potential in the treatment of a number of previously untreatable or difficult-to-treat diseases. However, the production of cAD-MSC for clinical application necessitates in vitro isolation and cell expansion, introducing the risk of microbiological contamination. Studies indicate that stored MSCs may be contaminated with bacteria, fungi, or viruses, resulting in cell transformation, cell death, or persistent infection. This ultimately compromises therapeutic efficacy and potentially facilitates therapy-induced pathogen transmission. In accordance with the European Medicines Agency guidelines mandating sterility testing as an integral component of the manufacturing process, this study aimed to assess the sterility of the cAD-MSC bank at the Croatian Veterinary Institute. To test for the most clinically significant canine pathogens, nucleic acids were extracted from 32 cAD-MSC preparations and analyzed using standard molecular PCR methods. The pathogen screening panel included rabies virus (Lyssavirus), canine herpesvirus (Varicellovirus canidalpha1), parvovirus (Carnivore protoparvovirus 1), coronavirus (Alphacoronavirus 1), distemper virus (Morbillivirus canis), Rotavirus A, Leptospira spp, Brucella canis, Borrelia burgdorferi sensu lato, Anaplasma spp, Ehrlichia spp, Mycoplasma spp (hemotropic), and Neospora caninum. No tested gene fragments of the aforementioned pathogens were detected, indicating that the cAD-MSC preparations were free from the presence of clinically significant pathogens. Rigorous implementation of sterility control during the cell isolation and expansion process is essential to ensure safe cell-based therapy in canine patients.