Evaluating the suitability of placental bovine explants for ex vivo modelling of host-pathogen interactions in Neospora caninum infections

Bovine abortions, often caused by infectious agents like Neospora caninum, inflict substantial economic losses. Studying host-pathogen interactions in pregnant cows is challenging, and existing cell cultures lack the intricate complexity of real tissues. To bridge the gap between in vitro and in vivo models, we explored the use of cryopreserved bovine placental explants. Building upon our successful development of protocols for obtaining, culturing, and cryopreserving sheep placental explants, we applied these methods to bovine tissues. Here, we compared fresh and cryopreserved bovine explants, evaluating their integrity and functionality over culture time. Additionally, we investigated their susceptibility to N. caninum infection. Our findings revealed that bovine explants deteriorate faster in culture compared to sheep explants, exhibiting diminished viability and function. Cryopreservation further exacerbated this deterioration. While fresh explants were successfully infected with N. caninum, parasite replication was limited. Notably, cryopreservation reduced infection efficiency. This pioneering work paves the way for developing ex vivo models to study reproductive pathogens in cattle. However, further optimization of the model is essential. These improved models will have the potential to significantly reduce the reliance on animals in research.