Addition of synthetic polymer in the freezing solution of mesenchymal stem cells from equine adipose tissue as a future perspective for reducing of DMSO concentration.

The regenerative therapies with stem cells (SC) has been increased by the cryopreservation, permitting cell storage for extended periods. However, the permeating cryoprotectant agents (CPAs) such as dimethylsulfoxide (DMSO) can cause severe adverse effects. Therefore, this study evaluated equine mesenchymal stem cells derived from adipose tissue (eAT-MSCs) in fresh (Control) or after slow freezing (SF) in different freezing solutions (FS). The FS comprise DMSO and non-permeating CPAs [Trehalose (T) and the SuperCool X-1000 (X)] in association or not, totalizing seven different FS: (DMSO; T; X; DMSO+T; DMSO+X; T+X, and DMSO+T+X). Before and after cryopreservation were evaluated, viability, colony forming unit (CFU), and cellular differentiation capacity. After freezing-thawing, the viability of the eAT-MSCs reduced (P< 0.05) in all treatments compared to the control. However, the viability of frozen eAT-MSCs in DMSO (80.3 ± 0.6) was superior (P<0.05) to the other FS. Regarding CFU, no difference (P>0.05) was observed between fresh and frozen cells. After freezing-thawing, the eAT-MSCs showed osteogenic, chondrogenic, and adipogenic lineages differentiation potential. Nonetheless, despite the significative reduction in the osteogenic differentiation capacity between fresh and frozen cells, no differences (P > 0.05) were observed among FS. Furthermore, the number of chondrogenic differentiation cells frozen in DMSO+X solution reduced (P<0.05) comparing to the control, without differ (P>0.05) to the other FS. The adipogenic differentiation did not differ (P>0.05) among treatments. In conclusion, although these findings confirm the success of DMSO to cryopreserve eAT-MSCs, the Super Cool X-1000 could be a promise to reduce the DMSO concentration in a FS.

As terapias regenerativas com células-tronco (CT) têm sido incrementadas pela criopreservação, permitindo o armazenamento celular. No entanto, os agentes crioprotetores (ACPs) penetrantes, como DMSO, podem causar efeitos adversos graves. Portanto, este estudo avaliou células-tronco mesenquimais equinas derivadas de tecido adiposo (CTM-TAe) in natura (Controle) ou após congelamento lento (CL) em diferentes soluções de congelamento (SC). As SCs compreendem DMSO e ACPs não permeáveis [Trealose (T) e o SuperCool X-1000 (X)] associados ou não: (DMSO; T; X; DMSO+T; DMSO+X; T +X e DMSO+T+X). Antes e após a criopreservação foram avaliados, viabilidade, unidade formadora de colônia (UFC) e capacidade de diferenciação celular. Após o congelamento-descongelamento, a viabilidade das CTM-TAe reduziu (P< 0,05) em todos os tratamentos em relação ao controle. Entretanto, a viabilidade das CTM-TAe congeladas em DMSO (80,3 ± 0,6) foi superior (P<0,05) às demais SC. Em relação às UFC, não houve diferença (P>0,05) entre células frescas e congeladas. Após congelamento-descongelamento, as CTM-TAe apresentaram potencial de diferenciação de linhagens osteogênicas, condrogênicas e adipogênicas. No entanto, apesar da redução significativa na capacidade de diferenciação osteogênica entre células frescas e congeladas, não foram observadas diferenças (P > 0,05) entre SCs. Além disso, o número de células de diferenciação condrogênica congeladas em solução de DMSO+X reduziu (P<0,05) em relação ao controle, sem diferir (P>0,05) das demais SCs. A diferenciação adipogênica não diferiu (P>0,05) entre os tratamentos. Em conclusão, embora esses achados confirmem o sucesso do DMSO para criopreservar CTM-TAe, o Super Cool X-1000 pode ser uma promessa para reduzir a concentração de DMSO.

Powdered coconut water (ACP 406®) as an alternative base culture medium for in vitro culture of goat preantral follicles enclosed in ovarian tissue.

This study evaluated a powdered coconut water solution (ACP 406®) as a base culture medium on the in vitro survival and development of in situ goat preantral follicles. The ovarian fragments were either immediately fixed in Carnoy solution (non-cultured control) or individually cultured for 2 or 6 days. The following culture media (all containing 100 µg/mL penicillin and 100 µg/mL streptomycin) were evaluated: α-MEM (α-MEM alone, without additional supplementation); α-MEM+ (supplemented α-MEM); ACP (ACP®406 alone); or ACP+ (supplemented ACP®406). Additional supplementation includes: 1.25 mg/mL bovine serum albumin, 10 µg/mL insulin, 5.5 µg/mL transferrin, 5 ng/mL selenium, 2 mM glutamine, and 2 mM hypoxanthine. The endpoints (i) follicular morphology; (ii) development; (iii) estradiol production; and (iv) reactive oxygen species (ROS) were recorded. Data were analyzed using chi-square, Turkey, t-test or One-Way ANOVA. Differences were considered significant when P < 0.05. At day 2 of culture, a greater (P < 0.05) percentage of morphologically normal follicles was observed between ACP+ and ACP treatments. Moreover, at day 2 of culture, no hormonal difference (P < 0.05) was observed between ACP+ and both α-MEM treatments. At day 6 of culture when ACP and α-MEM treatments were compared the percentage of healthy follicles were similar (P > 0.05) among treatments. Overall, all treatments had lower primordial follicles (P < 0.05) accompany by greater developing follicles (P < 0.05) percentages than non-cultured control treatment, indicating primordial follicle activation. However, at day 6 of culture, the percentage of primordial follicle development were similar (P > 0.05) among the treatments. Likewise, no differences (P > 0.05) were observed for ROS production and follicular and oocyte diameters among treatments. Therefore, ACP+ has the equivalent efficiency to MEM+ in maintaining the survival and development of goat preantral follicles, representing an alternative plant-based low-cost culture medium for in vitro culture.

Sheep Isolated Secondary Follicles Are Able to Produce Metaphase II Oocytes After Vitrification and Long-Term In Vitro Growth.

The vitrification of preantral follicles followed by in vitro growth (IVG) could be valuable to produce fertilizable oocytes. However, the meiotic resumption rates of oocytes cultured from vitrified secondary follicles (SF) have been reported as suboptimal. This study aimed to verify two base media (alpha modification of minimum essential medium, α-MEM, and tissue culture medium 199, TCM199) on vitrified SF regarding different requirements during IVG. Sheep ovarian fragments were divided in six groups: (1) Fresh groups (Control α-MEM and TCM199): SF without vitrification; (2) Follicle-Vitrified (Follicle-Vit α-MEM and TCM199): SF vitrified after isolation; and (3) Tissue-Vitrified (Tissue-Vit α-MEM and TCM199): SF vitrified enclosed in ovarian fragments and, subsequently, isolated. The isolated SF were submitted to IVG for 18 days. Thereafter, the recovered cumulus-oocyte complexes (COCs) underwent in vitro maturation (IVM) and evaluation of chromatin configuration. Follicular granulosa cells were analyzed for their gene expression of Bax, Bcl2, and Connexins (CX) 37 and 43. COCs from in vivo antral follicles were used as in vivo control. Data were analyzed by analysis of variance, Tukey, and chi-square tests. Differences were considered significant if p-value is <0.05. Follicle-Vit groups had higher (p < 0.05) percentage of antrum formation compared with Tissue-Vit groups. Vitrification did not affect (p > 0.05) oocyte diameter postmaturation. Oocytes from Follicle-Vit in α-MEM reached metaphase II stage after IVM. Gene expression for CX37, CX43, and Bax was lower in Tissue-Vit groups. For Bcl2, the gene expression was the opposite. In conclusion, during IVG for 18 days, maximal oocyte meiotic resumption was not negatively impacted by vitrification and was greatest for isolated SF using α-MEM as a medium.

Accelerated follicle growth during the culture of isolated caprine preantral follicles is detrimental to follicular survival and oocyte meiotic resumption.

This study investigated the effect of androstenedione (A4) alone or in association with different concentrations of bovine recombinant FSH on the IVC of isolated goat preantral follicles. Follicles were mechanically isolated from ovarian tissue and cultured for 18 days in α-minimum essential medium supplemented or not with A4 (10 ng/mL) alone or in association with fixed (A4 + FixFSH: 100 ng/mL) or sequential (A4 + SeqFSH: Day 0, 100 ng/mL; Day 6, 500 ng/mL; Day 12, 1000 ng/mL) concentrations of FSH. After 18 days, the oocytes were recovered for IVM and fluorescence analysis. At Day 18 of culture, only A4 + SeqFSH treatment showed a lower (P < 0.05) rate of intact follicles, survival probability, and meiotic resumption, as well as higher (P < 0.05) percentage of degeneration and/or extrusion after antrum formation. Taken together, these results reported a positive correlation between fast-growing follicles and follicles that degenerated and/or extruded after antrum formation. When compared with control, the addition of A4 alone or in association of FSH did not increase (P > 0.05) the estradiol production or androstenedione levels on Day 6. However, on Day 18, the androstenedione levels were significantly lower in A4 + SeqFSH treatment when compared with A4 alone or to A4 + FixFSH treatments, whereas the estradiol production did not differ (P > 0.05). In summary, this study found that accelerated follicle growth negatively impacted the morphology of caprine preantral follicle cultured in vitro. In addition, the association of androstenedione with increasing concentration of FSH was detrimental to follicular survival and oocyte meiotic resumption.

Ovine secondary follicles vitrified out the ovarian tissue grow and develop in vitro better than those vitrified into the ovarian fragments.

Cryopreservation of preantral follicles is a promising technique to preserve female fertility. The aim of this study was to evaluate the effect of vitrification on the development of secondary follicles included in ovarian tissue or isolated after microdissection. An important end point included is the capacity of grown oocytes to resume meiosis. Sheep ovarian cortexes were cut into fragments and split into three different groups: (1) fresh (control): secondary follicles isolated without any previous vitrification; (2) follicle-vitrification (follicle-vit): secondary follicles vitrified in isolated form; and (3) tissue-vitrification (tissue-vit): secondary follicles vitrified within fragments of ovarian tissue (in situ former) and subsequently subjected to isolation. From the three groups, isolated secondary follicles were submitted to IVC for 18 days. After IVC, cumulus-oocyte complexes (COCs) were harvested from follicles. As an additional control group, in vivo grown, in vivo-grown COCs were collected from antral ovarian follicles. All, recovered COCs were matured and the chromatin configuration was evaluated. Data were analyzed by ANOVA, and the means were compared by Student-Newman-Keuls test, and by chi-square. Differences were considered to be significant when P < 0.05. Isolated preantral follicles from all treatments had normal morphology, antrum formation, and low follicle degeneration after IVC. The growth rate between control and follicle-vit did not differ (P > 0.05), and was higher (P < 0.05) than for tissue-vit. The percentage of follicles that decreased diameter during IVC was significantly higher in tissue-vit than the in follicle-vit. Recovery rate of oocytes from normal follicles was higher in follicle-vit than in tissue-vit. Furthermore, oocyte viability was lower in tissue-vit than other treatments, and follicle-vit did not differ from control and in vivo grown. The percentage of oocytes meiosis resuming was not different between treatments except for in vivo grown. After vitrification, only follicle-vit showed metaphase I oocyte. We conclude that secondary follicles vitrified after isolation displayed a better follicular growth rate, oocyte viability, percentage of oocytes reaching the metaphase I stage, and fewer follicles with decreased diameter after IVC.

Connexin 37 and 43 gene and protein expression and developmental competence of isolated ovine secondary follicles cultured in vitro after vitrification of ovarian tissue.

Cryoinjuries caused by vitrification of tissues and organs lead to the loss of membrane proteins that mediate intercellular communications, such as connexins 37 (Cx37) and 43 (Cx43). Thus, the present study aimed to evaluate ovine Cx37 and Cx43 gene and protein expressions and developmental competence by in vitro-cultured secondary follicles retrieved from vitrified ovarian tissue. Ovarian fragments for the same ovary pair were distributed into six treatments: (1) fresh ovarian tissue (FOT); (2) vitrified ovarian tissue (VOT); (3) isolated follicles from fresh ovarian tissue (FIF); (4) isolated follicles from vitrified ovarian tissue; (5) isolated follicles from fresh ovarian tissue followed by in vitro culture (CFIF); (6) isolated follicles from vitrified ovarian tissue followed by in vitro culture (CVIF). In all treatments, Cx37 and Cx43 gene and protein expression patterns were evaluated by reverse transcription polymerase chain reaction and immunocytochemistry. In addition, secondary follicles were analyzed according to follicular integrity and growth, apoptosis, and cell proliferation. In vitro-cultured secondary follicles (CFIF and CVIF) were evaluated based on morphology (extruded follicles), antrum formation, and viability. The percentage of intact follicles was higher, whereas antrum formation, oocyte extrusion rate, and follicle viability were lower in CVIF than in CFIF treatment (P < 0.05). Terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphates nick end-labeling assay demonstrated that apoptosis was absent in FIF, whereas follicles from all other treatments showed positive labeling. Cell proliferation index was higher in isolated follicles from vitrified ovarian tissue and CVIF treatments than in follicles from FIF. Expression of Cx43 messenger RNA was lower in CVIF treatment when compared with follicles from all other treatments (P < 0.05). Follicle Cx37 messenger RNA levels did not show alterations in any treatment (P > 0.05). Cx37 and Cx43 immunolabeling was localized mainly on granulosa cells and oocytes, respectively. In conclusion, isolation of ovine secondary follicles could be done successfully after vitrification of ovarian tissue, and the basement membrane integrity remained intact after in vitro culture. Although the gene and protein expression of Cx37 did not change after vitrification of ovarian tissue, Cx43 turned out to be altered in secondary follicles after vitrification and in vitro culture.