Sea urchin Paracentrotus lividus immune cells in culture: formulation of the appropriate harvesting and culture media and maintenance conditions

The sea urchin is an emergent model system for studying basic and translational immunology. Here we report a new method for the harvesting and maintenance of primary immune cells isolated from adult Paracentrotus lividus, a common Mediterranean sea urchin species. This optimised method uses coelomocyte culture medium, containing a high-affinity Ca(2+) chelator, as the ideal harvesting and anti-clotting vehicle and short-term culture medium (≤48 h), and artificial seawater as the master medium that maintains cell survival and in vitro-ex vivo physiological homeostasis over 2 weeks. Gradually reducing the amount of anticoagulant solution in the medium and regularly replacing the medium led to improved culture viability. Access to a robust and straightforward in vitro-ex vivo system will expedite our understanding of deuterostome immunity as well as underscore the potential of sea urchin with respect to biomedicine and regulatory testing. This article has an associated First Person interview with the first author of the paper.