Efficient cryopreservation of Antillean manatee skin-derived somatic cells via reduced intracellular cryoprotectant concentration

Abstract

The declining population of the Antillean manatees has prompted interest in developing conservation strategies, including somatic cell cryopreservation. However, the type and concentration of intracellular cryoprotectant agents (CPAs) are limiting factors for its success. Therefore, we evaluated three concentrations (5, 8, 10%) of dimethyl sulfoxide (Me₂SO) and ethylene glycol (EG) to assess if reducing CPA concentration is efficient for the cells of these animals. Cells not subjected to cryopreservation were used as a control. All cells were analyzed for morphology, viability, metabolism, proliferative activity (PDT), apoptosis, levels of reactive oxygen species (ROS), and mitochondrial membrane potential (ΔΨm). Regardless of the solution used, the cryopreservation did not change frozen-thawed cells' morphology, metabolism, and apoptosis levels compared to control group cells (p > 0.05). Immediately after thawing, cells derived from the 8% Me₂SO group-maintained viability similar to the control; after in vitro culture of thawed cells, this positive response of viability was observed only in cells cryopreserved in solutions containing 5% and 8% CPA, regardless the type of CPA. Interestingly, cells frozen in 8% Me₂SO showed a higher PDT value than the other groups (p < 0.05). Cells frozen with 10% EG showed higher ROS than the control group (p < 0.05). Additionally, regardless of the solution used, cryopreservation resulted in a change in ΔΨm. In summary, reducing the concentration of CPAs (5 and 8%) helps with somatic cell quality, regardless of the CPA type used in Antillean manatees.

Keywords: Conservation strategies; Cryobanking; Dermal cells; Sirenians; Slow freezing.