Different cryopreservation requirements in foetal versus adult skin cells from an endangered mammal, the Iberian lynx (Lynx pardinus).

Cryobanking somatic foetal cells acquire much relevance in endangered species for biodiversity conservation purposes. Such cells could be later used to reintroduce the lost genes into the breeding pool, by inducing pluripotency and/or nuclear transfer if necessary. Since requirements for preserving foetal cells are not always the same as for adult ones, we evaluated the cryosensitivity of foetal skin cells in comparison with adult ones from the critically endangered Iberian lynx. Responses to cryoinjury were analyzed in both thawed cell types by means of cell viability and functionality (by analyzing their membrane integrity, metabolic activity, glycosaminoglycan content and proliferative activity). Freezing media included the permeating cryoprotectant Me2SO, either alone or along with the non-permeating cryoprotectant sucrose at 0.1 or 0.2M. When Me2SO was the only cryoprotectant, survival rate fell in thawed foetal cells to 54±4% (against 89±6% for thawed adult ones) and both proliferative and metabolic activities remained significantly lower than values for thawed adult cells. However, the combination of sucrose (both 0.1 as 0.2) and Me2SO in foetal cells significantly increased their survival rates (to 71±4% and 73±5%, respectively), proliferative activities (partially at day 7 and completely at day 14 after thawing) and metabolic activities. Our findings clearly show a difference between foetal and adult cells concerning their cryopreservation sensitivity and requirements, as well as their recovery time after thawing. These results are of relevance for the cryopreservation of foetal and adult cells from the Iberian lynx and could be also useful for other mammals.