Abstract
Simple SummaryOocyte vitrification is a cryopreservation method that guarantees the long-term conservation of genetic material and fertility potential in humans and wild or domestic animals. However, in the domestic cat the in vitro embryo development of immature vitrified oocytes is not yet satisfactory. In this study, a three-dimensional (3D) culture system was used for the in vitro embryo production of vitrified oocytes to provide conditions more similar to those of the in vivo microenvironment, and for comparison, control vitrified oocytes were cultured in two-dimensional (2D) conditions. Embryos were cultured for seven days and their development was assessed. The results showed that the 3D enriched culture system was able to sustain the in vitro maturation and the subsequent embryo development of vitrified oocytes, but no differences were found with the 2D system and improvements to enhance the development of vitrified oocytes are still needed.Cryoinjuries severely affect the competence of vitrified oocytes (VOs) to develop into embryos after warming. The use of culture conditions that provide physical and chemical support and resemble the in vivo microenvironment in which oocytes develop, such as 3D scaffolds and coculture systems, might be useful to improve VOs outcomes. In this study, an enriched culture system of 3D barium alginate microcapsules was employed for the in vitro embryo production of domestic cat VOs. Cryotop vitrified-warmed oocytes were in vitro matured for 24 h in the 3D system with or without fresh cumulus-oocyte complexes (COCs) in coculture, whereas a control group of VOs was cultured in traditional 2D microdrops of medium. After in vitro fertilization, presumptive embryos were cultured in 3D or 2D systems according to the maturation conditions. Vitrified oocytes were able to mature and develop into embryos in 3D microcapsules (17.42 ± 11.83%) as well as in 2D microdrops (14.96 ± 8.80%), but the coculture with companion COCs in 3D resulted in similar proportions of VOs embryo development (18.39 ± 16.67%; p = 1.00), although COCs presence allowed for blastocyst formation (0.95 ± 2.52%). In conclusion, embryos until late developmental stages were obtained from cat VOs, and 3D microcapsules were comparable to 2D microdrops, but improvements in post-warming conditions are still needed.
Highlights
Vitrification has widely improved oocyte cryopreservation techniques [1], but successful meiosis resumption and further embryo development of immature vitrified oocytes (VOs) are still difficultAnimals 2019, 9, 329; doi:10.3390/ani9060329 www.mdpi.com/journal/animalsAnimals 2019, 9, 329 to achieve compared to fresh gametes [2]
The developmental potential of VOs was similar in all of the tested conditions, without remarkable differences between the culture in the 3D or 2D system, the only treatment in which the blastocyst stage was obtained by VOs was 3D microcapsules in association with companion
Fresh cumulus-oocyte complexes (COCs) developed at higher rates compared to VOs, both as companion cells
Summary
Vitrification has widely improved oocyte cryopreservation techniques [1], but successful meiosis resumption and further embryo development of immature vitrified oocytes (VOs) are still difficultAnimals 2019, 9, 329; doi:10.3390/ani9060329 www.mdpi.com/journal/animalsAnimals 2019, 9, 329 to achieve compared to fresh gametes [2]. The developmental competence of VOs after the restoration of physiological conditions is severely impaired [2]. Oocytes grow in a complex environment where cell-to-cell contacts, communications, and stimulating signaling allow female gametes to acquire their developmental competence. To provide a more physiological environment for oocytes and embryos, three-dimensional (3D) culture systems have been applied with success. These systems, named scaffolds, were created and used for in vitro culture to provide a more suitable environment for cell growth, differentiation, and function [9], as they can trap cells or allow their migration and incorporate biologically active molecules [10,11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
