Cell Viability of Skin Tissue Collected from Postmortem Neotropical Deer: A Novel Perspective for Conservation Biotechnology

Considering the taxonomic uncertainties of Neotropical deer species, as well as the threat status of many of them, new studies and strategies for their maintenance are urgently needed. Obtaining live cells is of great importance for the conservation of wild species in order to allow cytogenetic and molecular studies to be carried out and for the construction of genomic resource banks. In order to increase the genetic diversity stored in these banks, the possibility of collecting skin fragments from dead animals (e.g., run over, hunted, deaths related to disease or natural causes) becomes a valuable source and a last alternative for obtaining material from these individuals. However, the interval between the death of the animal and the collection of tissue can directly interfere with the quality of the sample obtained and it is therefore essential to identify the maximum time during which viable cells are still found. Thus, this study sought to establish a protocol for the collection, storage, cryopreservation, and cultivation of skin obtained postmortem from individuals of the species Subulo gouazoubira (gray brocket deer) and Mazama rufa (red brocket deer). The collection of tissue fragments at different postmortem intervals (0 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, and 11 h) was evaluated. The tissues were analyzed for fibroblast cell viability immediately after collection. Their ability to undergo cryopreservation was evaluated based on techniques that can be directly applied to samples obtained in the field and their subsequent thawing and success of cell cultures was performed in the laboratory. Regarding the genetic integrity of the cells, the number of metaphases was observed by the mitotic index. The cell viability presented by the samples always remained above 60%. It was possible to establish cell cultures even with the tissues obtained 11 h after the death of the individuals: however, they required twice as many days to reach bottle confluence compared to the cultures performed with the tissues obtained 0 h after the death of the individuals. The results suggest that the best rates of cell viability, time to reach confluence, and number of metaphases per cell (mitotic index) are found in skin fragments collected up to 5 h after the death of individuals when their carcasses are kept at room temperature.