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

A Method to Freeze Skin Samples for Cryobanks: A Test of Some Cryoprotectants for an Endangered Deer

The genetic diversity of endangered deer species, such as Mazama jucunda, can be preserved with the help of somatic cell cryopreservation. This procedure allows obtaining several cells from the individual even after its death, which is very important for applications in reproductive biotechnologies. This study's objective was to test cryopreservation protocols of skin fragments of M. jucunda, using different cryoprotectants in slow freezing. We evaluated four treatments, composed of three cryoprotectants, dimethyl sulfoxide (DMSO), polyvinylpyrrolidone (PVP), and ethylene glycol (EG), used alone and in combination. There was also a control group where the tissue did not undergo cryopreservation. Skin fragments were collected from the medial region of the pelvic limbs of three individuals. Each fragment was divided into 10 equal parts, standardized by weight, making two pieces for each treatment and control from each animal. The collected fragments were evaluated in culture, based on the speed of occupation of the free spaces of the cell culture flask. Cell viability was also evaluated using Trypan Blue dye and the mitotic index to understand the effect of toxicity and freezing on cell membrane integrity and cell division capacity, respectively. The treatments that used association with PVP proved to be more damaging to the cells, taking longer to reach confluence. EG alone showed better results than DMSO in the slow-freezing protocol. Clinical Trial Registration Number is 1390/21.

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.

Interactions Among Sucrose and Concentrations of Serum Fetal Bovine on the Cryopreservation of Somatic Cells Derived from Red-Rumped Agoutis

BACKGROUND: The synergistic action among the different extracellular cryoprotectants could improve somatic cell quality after thawing and provide bases for the formation of biobanks for redrumped agoutis. OBJECTIVE: This study evaluated the interactions among sucrose (SUC) and concentrations of serum fetal bovine (FBS) on the cryopreservation of somatic cells derived from redrumped agoutis. MATERIALS AND METHODS: Cells were cryopreserved with 10% dimethyl sulfoxide and different concentrations of FBS (10%, 40%, and 90%) with or without 0.2 M SUC, totaling six comparison groups. Non-cryopreserved cells were used as a control. Cells were evaluated for viability, metabolic activity, proliferative activity, reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm) and apoptosis levels. RESULTS: No difference was observed among cryopreserved with DMSO containing (10FBS, 10FBS-SUC, 40FBS, 40FBS-SUC, 90FBS, 90FBSSUC) and non-cryopreserved groups for viability, metabolic activity, proliferative activity, and ROS levels. Interestingly, only cells cryopreserved with 90% FBS and SUC maintained the ΔΨm like the control. This indicates that at high concentrations of FBS, SUC contributes to the maintenance of this parameter in cryopreserved cells. Moreover, at concentrations of 10% and 40% of FBS, SUC contributed to the maintenance of viability evaluated by the levels of apoptosis evaluated after thawing. In summary, we verified that 90% FBS and 0.2 M SUC promote greater ability of cells after thawing. Additionally, SUC positively acts in cryopreservation solutions containing 10% and 40% FBS. CONCLUSION: This information is essential to an understanding of the mechanisms involved in the interactions of extracellular cryoprotectants in somatic cell cryopreservation solutions of red-rumped agoutis.

Comparison between concentration and type of intracellular cryoprotectants and the presence of sucrose for cryobanks of somatic cells derived from captive Pumas

The loss of wild biodiversity has prompted the development of cryobanks, such as those of somatic cells. This is the reality of Pumas, wild felids of ecological importance that suffer from anthropogenic actions, population decline, and subsequent loss of genetic diversity. Somatic cell banks are a strategy for conserving population diversity. We compared different concentrations and types of intracellular cryoprotectants (dimethyl sulfoxide, DMSO; ethylene glycol, EG) associated with 0.2 M of sucrose (SUC) in the cryopreservation of the somatic cells of captive Pumas. The cells were cryopreserved by slow freezing with different solutions containing Dulbecco's modified Eagle's medium with 10% fetal bovine serum and varying concentrations of DMSO and EG in the absence or presence of SUC. The cells were analyzed for morphological characteristics, viability, proliferative activity, metabolic activity, and apoptosis levels. Cells maintained similar fusiform morphology before and after cryopreservation. There was no difference in viability, regardless of the reduction in the concentration and type of intracellular cryoprotectants and sucrose. Similarly, proliferative activity, metabolic activity, and apoptosis levels were not altered by the composition of the cryoprotectants. In summary, we demonstrate that reducing the concentration of DMSO or EG ensures adequate cryopreservation of Puma somatic cells, regardless of the presence of SUC.

Effects of somatic tissue cryopreservation on puma (Puma concolor L, 1771) tissue integrity and cell preservation after in vitro culture

Somatic resource banks play a crucial role in the conservation of genetic diversity, allowing for the preservation of biological samples from different populations. Puma somatic cells can be recovered from these banks and used in assisted techniques toward enhancing their multiplication and conservation. In response to the population reduction of this ecologically importance species, we aimed to evaluate the capacity of cryopreservation of somatic tissues on the maintenance of the integrity and quality of the cells recovered after culture, with the aim of establishing a somatic tissue bank that will allow for the safeguarding of a wide genetic sampling of pumas. Cryopreservation increased the thickness of the corneum layer in the tissues, and the number of perinuclear halos and empty gaps. Nevertheless, cryopreservation was able to maintain normal fibroblast patterns, even showing an increase in the percentage of collagen fibers. Cryopreservation maintained the proliferative potential of the tissues and the parameters evaluated during in vitro culture, mainly regarding the viability, proliferative activity, and apoptosis levels. Nevertheless, cells from cryopreserved tissues showed decreased metabolism and mitochondrial membrane potential when compared to cells from non-cryopreserved tissues. In summary, we demonstrated for the first time that puma somatic tissues subjected to cryopreservation are viable and maintain tissue integrity, featuring minimal changes after warming. Although viable somatic cells are obtained from these tissues, they undergo alterations in their metabolism and mitochondrial membrane potential. Improvements in the conservation conditions of somatic samples are needed to increase the quality of somatic tissue banks in this species.

Isolation, characterization, and cryopreservation of collared peccary skin-derived fibroblast cell lines

Background

Biobanking of cell lines is a promising tool of support for wildlife conservation. In particular, the ability to preserve fibroblast cell lines derived from collared peccaries is of significance as these wild mammals are unique to the Americas and play a large role in maintaining the ecosystem. We identified collared peccary fibroblasts by immunofluorescence and evaluated their morphology, growth and adherence capacity. Further, we monitored the viability and metabolic activity of the fibroblasts to determine the effects of passage number and cryopreservation on establishment of cell lines.

Methods

Skin biopsies were collected from the peripheral ear region from five adult animals in captivity. Initially, cells were isolated from fragments and cultured in the Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum and 2% antibiotic-antimycotic solution under a controlled atmosphere (38.5 °C, 5% CO₂). We evaluated the maintenance of primary cells for morphology, adherence capacity of explants, explants in subconfluence, cell growth and absence of contamination. Moreover, we identified the fibroblast cells by immunofluorescence. Additionally, to evaluate the influence of the number of passages (first, third and tenth passage) and cryopreservation on establishment of cell lines, fibroblasts were analysed for the viability, metabolic activity, population doubling time (PDT), levels of reactive oxygen species (ROS), and mitochondrial membrane potential (ΔΨm).

Results

All explants (20/20) adhered to the dish in 2.4 days ± 0.5 with growth around the explants in 4.6 days ± 0.7, and subconfluence was observed within 7.8 days ± 1.0. Moreover, by morphology and immunocytochemistry analyses, cells were identified as fibroblasts which presented oval nuclei, a fusiform shape and positive vimentin staining. No contamination was observed after culture without antibiotics and antifungals for 30 days. While there was no difference observed for cell viability after the passages (first vs. third: P = 0.98; first vs. tenth: P = 0.76; third vs. tenth: P = 0.85), metabolic activity was found to be reduced in the tenth passage (23.2 ± 12.1%) when compared to that in the first and third passage (100.0 ± 24.4%, P = 0.006). Moreover, the cryopreservation did not influence the viability (P = 0.11), metabolic activity (P = 0.77), or PDT (P = 0.11). Nevertheless, a greater ΔΨm (P = 0.0001) was observed for the cryopreserved cells (2.12 ± 0.14) when compared to that in the non-cryopreserved cells (1.00 ± 0.05). Additionally, the cryopreserved cells showed greater levels of intracellular ROS after thawing (1.69 ± 0.38 vs. 1.00 ± 0.22, P = 0.04).

Conclusions

This study is the first report on isolation, characterization and cryopreservation of fibroblasts from collared peccaries. We showed that adherent cultures were efficient for obtaining fibroblasts, which can be used as donor cells for nuclei for species cloning and other applications.

Potential role of intraspecific and interspecific cloning in the conservation of wild mammals

Intraspecific and interspecific cloning via somatic cell nuclear transfer (iSCNT) is a biotechnique with great possibilities for wild mammals because it allows the maintenance of biodiversity by recovering species, nuclear reprogramming for the production of pluripotency-induced cells, and studies related to embryonic development. Nevertheless, many areas in cloning, especially those associated with wild mammals, are still in question because of the difficulty in obtaining cytoplasmic donor cells (or cytoplasts). Conversely, donor cell nuclei (or karyoplasts) are widely obtained from the skin of living or post-mortem individuals and often maintained in somatic cell banks. Moreover, the creation of karyoplast–cytoplast complexes by fusion followed by activation and embryo development is one of the most difficult steps that requires further clarification to avoid genetic failures. Although difficult, cloning different species, such as wild carnivores and ungulates, can be successful via iSCNT with embryo development and the birth of offspring. Thus, novel research in the area that contributes to the conservation of biodiversity and knowledge of the physiology of species continues. The present review presents the failures and successes that occurred with the application of the technique in wild mammals, with the goal of helping future work on cloning via iSCNT.

CÉLULAS FETAIS BOVINAS DE CULTIVO PRIMÁRIO SUBMETIDAS A DIFERENTES PRESSÕES NEGATIVAS ANTES DO CONGELAMENTO EM PALHETAS

Resumo O congelamento de células é uma importante ferramenta na preservação de espécies ameaçadas de extinção. Células fetais de cultivo primário obtidas de um bovino clone foram submetidas à pressão negativa (PN) de 200, 500 ou 800 mbar, imediatamente (PN0h) ou três horas antes (PN3h) do congelamento em palhetas finas, com 10% de DMSO como crioprotetor. Células frescas e congeladas sem submissão à PN foram utilizadas como controles. Avaliou-se a viabilidade pós-descongelamento, a curva de proliferação celular, assim como o tempo de duplicação da população (PDT) celular, a cada 24 horas, durante oito dias. Os dados obtidos foram submetidos ao teste de Tukey ou Qui quadrado (P≤0,05). A sobrevivência média dos grupos controle (89,8%) e PN500 0h (88,1%) foi superior aos outros grupos; o tempo de PDT foi semelhante nos grupos fresco (27,5 ± 0,35 h), controle congelado (30,1 ± 2,3 h) e PN500 0h (32,4 ± 1,6 h). O menor tempo foi observado no grupo PN800 0h (21,9 h). O congelamento de células fetais bovinas de cultivo primário, realizado em palhetas de 0,25 mL, com 10% de DMSO, possibilita elevadas taxas de sobrevivência após o descongelamento. A PN modifica a curva de crescimento de células criopreservadas, sendo que as intensidades de 200 ou 500 mbar, aplicadas imediatamente antes do congelamento das células, possibilitam curvas de proliferação semelhantes às obtidas com células frescas.

Use of somatic cell banks in the conservation of wild felids

The conservation of biological resources is an interesting strategy for the maintenance of biodiversity, especially for wild felids who are constantly threatened with extinction. For this purpose, cryopreservation techniques have been used for the long-term storage of gametes, embryos, gonadal tissues, and somatic cells and tissues. The establishment of these banks has been suggested as a practical approach to the preservation of species and, when done in tandem with assisted reproductive techniques, could provide the means for reproducing endangered species. Somatic cell banks have been shown remarkable for the conservation of genetic material of felids; by merely obtaining skin samples, it is possible to sample a large group of individuals without being limited by factors such as gender or age. Thus, techniques for somatic tissue recovery, cryopreservation, and in vitro culture of different wild felids have been developed, resulting in a viable method for the conservation of species. One of the most notable conservation programs for wild felines using somatic samples was the one carried out for the Iberian lynx, the most endangered feline in the world. Other wild felids have also been studied in other continents, such as the jaguar in South America. This review aims to present the technical progress achieved in the conservation of somatic cells and tissues in different wild felids, as well address the progress that has been achieved in a few species.

Combination of ethylene glycol with sucrose increases survival rate after vitrification of somatic tissue of collared peccaries (Pecari tajacu Linnaeus, 1758)

ABSTRACT: The cryopreservation of somatic tissue in collared peccaries promotes an alternative source of genetic material of this specie. The solid-surface vitrification (SSV) is a great option for tissue conservation; nevertheless, the optimization of SSV requirements is necessary, especially when referred to cryoprotectants that will compose the vitrification solution. Therefore, the aim was to evaluate the effect of the presence of 0.25 M sucrose in addition to different combinations (only or association) and concentrations (1.5 M or 3.0 M) of ethylene glycol (EG) and/or dimethyl sulfoxide (DMSO) in the somatic tissue vitrification of collared peccaries. Subsequently, we tested six combinations of cryoprotectants with or without sucrose in Dulbecco modified Eagle medium (DMEM) plus 10% fetal bovine serum (FBS). Thus, 3.0 M EG with sucrose was able to maintain normal tissue characteristics compared with non-vitrified (control), especially for the volumetric ratio of epidermis (61.2 vs. 58.7%) and dermis (34.5 vs. 36.6%), number of fibroblast (90.3 vs. 127.0), argyrophilic nucleolar organizer region (AgNOR) ratio (0.09 vs. 0.17%) and nucleus area (15.4 vs. 14.5 μm2) respectively. In conclusion, 3.0 M EG with 0.25 M sucrose and 10% FBS resulted in a better cryoprotectant composition in the SSV for somatic tissue of collared peccaries.

Influence of Cryopreservation Solution on the In Vitro Culture of Skin Tissues Derived from Collared Peccary (Pecari tajacu Linnaeus, 1758)

Skin vitrification is a promising and alternative tool for the conservation of biodiversity, especially for wild mammals, such as collared peccaries. Several factors can affect the success of this procedure, such as the cryoprotectant solution used. Therefore, this study was carried out to compare the efficiency of various vitrification solutions for recovery of viable cells after in vitro culture of cryopreserved skin tissues derived from the collared peccary, aiming to study the application in biobanking, where cellular use is not immediately required. Then, Dulbecco's modified Eagle's medium (DMEM) composed of 2.2 g/L sodium bicarbonate and 10% fetal bovine serum (FBS) was supplemented with 3.0 M ethylene glycol (EG) or 3.0 M dimethyl sulfoxide (DMSO) or 1.5 M EG plus 1.5 M DMSO with or without sucrose (SUC; 0.25 M) to produce six solutions for solid-surface vitrification. After warming, skin tissues were cultured in vitro and recovered cells were analyzed for morphology, adhesion, subconfluence, and proliferative activity for developing the growth curve and determining the population doubling time (PDT), and viability by Trypan Blue. The vitrification did not alter the ability of the tissues to adhere to the culture dish, as well as the day of all explants with cell growth, subconfluence samples, subconfluence total time, and PDT (p > 0.05). Moreover, independent of the cryoprotectant solution used, the vitrification altered the day of all attached explants (p < 0.05). Nevertheless, for viability after the first passage, only the EG-SUC (86.9%) and DMSO-SUC (91.4%) groups maintained viable cell recovery similar to the nonvitrified group (96.3%, p > 0.05). Additionally, for viability after the third passage, only the EG-SUC group maintained the cell quality (88.3%), when compared with the nonvitrified (97.8%, p > 0.05). In conclusion, DMEM with 10% FBS, 3.0 M EG, and 0.25 M sucrose was the most efficient solution for vitrifying collared peccary skin tissues, leading to the in vitro culture of viable cells.

Insights on Cryopreserved Sheep Fibroblasts by Cryomicroscopy and Gene Expression Analysis

Cryopreservation includes a set of techniques aimed at storing biological samples and preserving their biochemical and functional features without any significant alterations. This study set out to investigate the effects induced by cryopreservation on cultured sheepskin fibroblasts (CSSF) through cryomicroscopy and gene expression analysis after subsequent in vitro culture. CSSF cells were cryopreserved in a cryomicroscope (CM) or in a straw programmable freezer (SPF) using a similar thermal profile (cooling rate -5°C/min to -120°C, then -150°C/min to -196°C). CSSF volume and intracellular ice formation (IIF) were monitored by a CM, while gene expression levels were investigated by real-time polymerase chain reaction in SPF-cryopreserved cells immediately after thawing (T0) and after 24 or 48 hours (T24, T48) of post-thaw in vitro culture. No significant difference in cell viability was observed at T0 between CM and SPF samples, while both CM and SPF groups showed lower viability (p < 0.05) compared to the untreated control group. Gene expression analysis of cryopreserved CSSF 24 and 48 hours post-thawing showed a significant upregulation of the genes involved in protein folding and antioxidant mechanisms (HPS90b and SOD1), while a transient increase (p < 0.05) in the expression levels of OCT4, BCL2, and GAPDH was detected 24 hours post-thawing. Overall, our data suggest that cryostored CSSF need at least 24 hours to activate specific networks to promote cell readaptation.

Conservation of somatic tissue derived from collared peccaries (Pecari tajacu Linnaeus, 1758) using direct or solid-surface vitrification techniques

Cryopreservation of somatic tissue can be applied in biodiversity conservation, especially for wild species as collared peccary. We aimed to evaluate the effect of vitrification techniques of ear tissue of collared peccary [direct vitrification in cryovials (DVC) or solid-surface vitrification (SSV)] on the layers of epidermis and dermis by conventional histology and cell ability during the in vitro culture. Thus, both the vitrification methods were able to maintain normal patterns of the epidermis as the cornea and granular layers, furthermore the intercellular space and dermal-epidermal junction of the spinous layer when compared to fresh control. Nevertheless, DVC and SSV percentage of normality decreased in the morphological integrity of cytoplasm (37.5 and 25.0%) of spinous layer, respectively, as compared to the fresh fragments (100%, p < 0.05). Moreover, other differences between the fresh control (100%) and DVC tissues were verified in the intra-epidermal cleavage of the spinous (37.5%) and basal (37.5%) layers. In general, DVC and SSV techniques were efficient for the recovery of the somatic cells according to most of the evaluated parameters for the in vitro culture (p > 0.05). In addition, only at time of 72 h (D3), in the growth curve, DVC fragments showed a reduced cell concentration than fresh control. In conclusion, SSV was found to be a more efficient method for vitrifying collared peccary skin tissue when compared to DVC. These results are relevant for the tissue cryopreservation from collared peccary and could also be useful for mammals with phylogenetic relationships.

In vitro culture of somatic cells derived from ear tissue of collared peccary (Pecari tajacu Linnaeus, 1758) in medium with different requirements

ABSTRACT: The maintenance of metabolic activities during the in vitro culture of somatic cells of wild animals, especially collared peccary (Pecari tajacu), is an interesting step in conservation of these cells for the use in nuclear transfer. In this context, it is necessary to optimize the culture conditions of somatic cells by the establishment of appropriate supplementation to the media. Therefore, this study aimed to analyze the composition of the culture means of somatic cell derived from ear tissue of collared peccaries, evaluating concentrations of fetal bovine serum (FBS; 10% vs. 20%) and epidermal growth factor (EGF; 5ng/mL vs. 10ng/mL). Tissues were submitted to primary culture and subcultures for 40 days and cells were analyzed for morphology, adhesion, subconfluence, and proliferative activity to develop the growth curve and to determine the population doubling time (PDT), viability, and functional/metabolic activity. No difference was observed between the concentrations of FBS for several parameters, except for viability [FBS10: 85.6% vs. FBS20: 98.2%], PDT [FBS10: 155.4h vs. 77.2h], and functional/metabolic assay [FBS10: 0.57-0.55 vs. FBS20: 0.82-0.99 (D5-D7)]. For the EGF in culture, no difference was observed in the evaluated parameters. In all experiments, the growth curves were typical S-shape and the cells passed through a lag, logarithmic, and plateau phase. In conclusion, 20% FBS is suitable for the recovery of somatic cells; nevertheless, EGF does not improve the quality of growing these cells. To our knowledge, this is the first study culturing somatic cells of collared peccaries.