Cryopreservation of Brown Bear Skin Biopsies

The initial steps toward the formation of somatic tissue banks and cell cultures derived from captive Antillean manatee (Trichechus manatus manatus) skin biopsies

The declining population of the Antillean manatee caused by ecosystem degradation and rising pollution has prompted interest in developing conservation strategies for this species. Given this scenario, somatic tissue banks are important tools for acquiring knowledge about the species, as well as for obtaining somatic cells for biotechnological and ecotoxicological applications. Therefore, we aimed to assess the effects of slow freezing (SF) and solid-surface vitrification (SSV) of the dermis of captive Antillean manatees on the histology and ultrastructure of the tissue and cell viability in culture. While the SSV did not change the dermis thickness, the SF maintained the tissue proliferative potential, assessed by the nucleolar organizer region area, similar to noncryopreserved tissues. Moreover, both techniques reduced the number of fibroblasts and increased the percentage of collagen fibers. Nevertheless, only tissues cryopreserved with SF and noncryopreserved tissues were able to produce cells after in vitro culture. Although SF did not alter cell viability and proliferative activity, cells derived from cryopreserved tissues showed decreased metabolism, altered apoptosis, increased levels of reactive oxygen species, and mitochondrial membrane potential compared to cells from noncryopreserved tissues. In summary, we demonstrated for the first time that Antillean manatee somatic tissues can be cryopreserved by SF, and cells can be obtained after in vitro culture. Improvements in cryopreservation conditions, especially vitrification, of somatic samples are needed to increase the quality of somatic tissue banks in this species.

Influence of Intracellular Cryoprotectants on the Conservation of Dermal Somatic Tissues Derived from Antillean Manatees (Trichechus manatus manatus Linnaeus, 1758)

Cryopreservation of somatic tissue has been studied as a tool for the knowledge and conservation of endangered species, such as Antillean manatees. The use of vitrification protocols is an important step in the establishment of biological banks. To decrease the damage caused by this technique, a reduction in the concentration of cryoprotectants has been proposed. Therefore, we aimed to evaluate combinations and concentrations of intracellular cryoprotectants for the conservation of somatic tissues derived from Antillean manatees. Dulbecco's modified Eagle's medium, F-12 composed of 10% fetal bovine serum and 0.25 M sucrose, was supplemented with 3.0 M ethylene glycol (EG) plus 3.0 M dimethyl sulfoxide (DMSO), or 1.5 M EG plus 1.5 M DMSO or 3.0 M EG or 3.0 M DMSO, to produce four solutions for solid-surface vitrification. Noncryopreserved tissues were used as the controls. After warming, tissues derived from four Antillean manatees were evaluated for ultrastructure, histology, and in vitro culture. No differences were observed among the cryopreserved and noncryopreserved tissues in terms of ultrastructure. The dermis thickness of the cryopreserved fragments in solutions containing 3.0 M EG plus 3.0 M DMSO, 3.0 M EG, and 3.0 DMSO was similar to that of the control. Moreover, cryopreservation with 3.0 M EG plus 3.0 M DMSO maintained tissue proliferative capacity potential evaluated by quantification of nucleolar organizing regions. Nevertheless, none of the cryopreserved fragments were able to maintain the number of fibroblasts and the collagen percentage as compared with that of the noncryopreserved fragments. Also, none of the cryopreserved fragments in the different solutions were able to produce cells in vitro. In summary, even reducing the concentration of intracellular cryoprotectants as well as their association did not guarantee the maintenance of cells after in vitro culture. Further studies are needed to optimize the cryopreservation protocols in Antillean manatee somatic tissues.

Effects of Refrigeration at 5°C for Long Periods of Time on Bovine Ear Skin as a Strategy to Transport Biological Material and Isolate Fibroblasts to Use in the Nuclear Transfer

Animal cloning is an important technique used to produce clones from valuable farm animals, to rescue animals in risk of extinction, and for producing transgenic animals. The objective of this work was to evaluate the effects of refrigeration on bovine ear skin as a strategy to transport biological material for long periods of time to isolate viable fibroblasts. Ears from eight cows were collected after death and stored for 30 days at 5°C. On days 0, 2, 4, 7, 14, 21, and 30, skin biopsies were cultured in vitro for fibroblast isolation. The time for first fibroblast outgrowth, time to reach 100% confluence. and cell concentration before freezing were observed for each period. In addition, plasma membrane integrity, cell apoptosis, and necrosis in cells were evaluated through fluorescent colorant combination in a flow cytometer from all periods after thawing. Fibroblasts obtained after 30 days of storage, considered a critical period, were tested for embryo production using nuclear transfer (NT) with micromanipulators. All time points allowed for cell culture. The time of cell growth onset was longer in samples refrigerated for 14, 21, and 30 days. The time to reach confluence also increased with longer refrigeration periods. Cells from day 0 reached confluence in 24 ± 2 days, while day 30 cells took 31 ± 0 days. Cell concentration and viability dropped with increased storage time and freezing/thawing, respectively. It was found that a long period of sample storage results in cell damage, making cultivation more difficult and decreasing cell viability post-thawing and cell concentration. However, when cells from day 30 were used as nuclei donors in NT, a 26.05% blastocyst rate after 7 days in culture was obtained. In conclusion, refrigeration at 5°C was shown to be efficient in maintaining viable tissue for up to 30 days, and fibroblasts isolated can be used for cloned embryo production.