Characterization of the First Turtle Organoids: A Model for Investigating Unique Adaptations with Biomedical Potential

ABSTRACT

Painted turtles are remarkable for their well-developed freeze tolerance and associated resilience to hypoxia/anoxia, oxidative stress, and ability to supercool. They are, therefore, an ideal model for biomedical research on hypoxia-induced injuries (including strokes), tissue cooling during extensive surgeries, and organ cryopreservation. Yet, the seasonal reproduction and slow maturation of turtles hinder basic and applied biomedical research. To overcome these limitations, we developed the first adult stem cell-derived turtle hepatic organoids, which provide 3D self-assembled structures that mimic their original tissue and allow for in vitro testing and experimentation without constantly harvesting donor tissue and screening offspring. Our pioneering work with turtles represents the first for this vertebrate Order and complements the only other organoid lines from non-avian reptiles, derived from snake venom glands. Here we report the isolation and characterization of hepatic organoids derived from painted, snapping, and spiny softshell turtles spanning ∼175 million years of evolution, with a subset being preserved in a biobank. Morphological and transcriptomics revealed organoid cells resembling cholangiocytes, which was then compared to the tissue of origin. Deriving turtle organoids from multiple species and life stages demonstrates that our techniques are broadly applicable to chelonians, permitting the development of functional genomic tools currently missing in most herpetological research. When combined with genetic editing, this platform will further support studies of genome-to-phenome mapping, gene function, genome architecture, and adaptive responses to climate change, among others. We discuss the unique abilities of turtles, including their overwintering potential, which has implications for ecological, evolutionary, and biomedical research.