When Simplicity Matters: Simplified Skin Tissue Cryopreservation Media for Wildlife Conservation

Introduction: The conservation of threatened species requires effective strategies to preserve genetic diversity, with genome resource banks representing a valuable tool in this context. However, many cryopreservation protocols rely on complex media and laboratory infrastructure, limiting their applicability under field conditions. Objectives: This study evaluated whether simplified cryopreservation media composed of widely available reagents could effectively preserve skin tissue from Neotropical deer using slow freezing and needle-immersed vitrification. Methods: Skin samples from red brocket deer ( Mazama rufa ) and marsh deer ( Blastocerus dichotomus ) were cryopreserved using conventional media (Ham′s F10 with 10% fetal bovine serum, 0.5 M sucrose and 2.8 M dimethyl sulfoxide) or simplified saline-based formulations containing 0.5 M commercial table sugar and 2.8 M dimethyl sulfoxide. Post-thaw viability, mitochondrial activity, histomorphology, apoptosis, and fibroblast culture were evaluated. Results: Fibroblast cultures were successfully established from fresh and cryopreserved skin tissues, with cell migration occurring within 2–5 days and 70% confluence reached between 13 and 19 days depending on protocol. In red brocket, slow freezing showed higher post-thaw cell viability (79.2 ± 4.96% and 80.7 ± 8.26%) than vitrification (63.0 ± 12.3% and 59.2 ± 10.6%; p = 3.03 × 10 −5 ), but lower mitochondrial activity (69.5 ± 10.5%) compared with needle-immersed vitrification, which showed lower viability (59%–63%) but higher mitochondrial activity (90.1 ± 8.9% and 94.1 ± 5.2%; p = 0.00208). In marsh deer, viability differed significantly among protocols ( p = 0.0194), with fresh tissue showing higher viability than conventional and simplified vitrification, while mitochondrial activity showed no significant differences ( p = 0.9885). Simplified media performed comparably to conventional formulations across both cryopreservation techniques. Species-specific responses were evident, with marsh deer tissues showing similar responses across cryopreservation strategies, whereas red brocket exhibited greater sensitivity to vitrification. Conclusions: The adoption of accessible and field-adapted cryopreservation strategies may facilitate implementation of somatic cell biobanking.