Equine (Equus caballus) primary post-natal brain-derived cells: immortalization and preliminary reprogramming attempts to induced pluripotent stem cells.

Equines represent an underexplored yet highly relevant model for studying neurological diseases within a One Health framework. Here, we report the first establishment of post-natal equine brain-derived in vitro systems, including equine primary post-natal brain-derived cells (EpBCs) and their immortalized counterparts (EiBCs). EpBCs were isolated from the hippocampus and successfully expanded, while immortalization via Simian virus 40 large T antigen generated EiBCs lines with distinct transcriptomic reprogramming characterized by cell cycle activation and partial dedifferentiation. Despite testing three non-integrating approaches-Sendai virus, episomal vectors, and synthetic mRNA-no induced pluripotent stem cells (iPSCs)-like colonies were detected under the tested conditions, possibly reflecting a combination of species-specific, cell-intrinsic, and donor-specific factors, as well as culture conditions, factor compatibility, and delivery efficiency. Together, these findings establish a foundational equine brain-derived cell platform and highlight key challenges in equine reprogramming. Its One Health relevance is prospective, as this system may support future comparative neurological research and the development of equine brain organoids.