P.21: Reproductive ability of minipigs as surrogates for somatic cell nuclear transfer

Background: Pigs are genetically, anatomically, and physiologically similar to humans. In addition, they have been used in various research in the fields of toxicology and pharmacology due to the characteristics of well-defined reproduction, a large number of live offspring, and rapid growth into adulthood. Also, recently, pigs are in the spotlight as a suitable source animal for xenotransplantation. Objectives: There is abundant data from embryo transfer (ET) experiments using farm pigs as surrogates, but data on ET experiments using minipigs, which are easy to raise as surrogates, are scarce. Therefore, in this study, the differences related to pregnancy were compared when somatic cell nuclear transfer-derived embryos were transferred to farm pigs or minipigs as surrogate mothers. Methods: A total of 80 minipigs were used for ET experiments using transgenic embryos. After transplantation, the early pregnancy and delivery rates were investigated. The factors that can affect the pregnancy rate such as 1) estrus synchronization program, 2) ovulation status at the time of ET, 3) the number of repeated ET surgeries, and 4) the ET sites, were changed, and the differences on the pregnancy rate were observed in minipigs. In the case of minipigs that gave birth, the size of the fetal sac on the 28th day of ET was also measured by ultrasound. Results: Even we changed the conditions or surgical methods, there were no statistically significant differences in implantation rate and delivery rate in minipigs. The diameter of the implanted fetal sac on the 28th day after ET in the minipigs whose delivery was confirmed was calculated to be 4.7 ± 0.5 cm. Conclusions: It was confirmed that there were no significant differences in pregnancy rate of minipigs in the comparative experiment on various factors affecting the pregnancy rate. However, additional experiments and analyses are needed due to the large individual differences of the minipigs. This research was supported by a grant from the Korea Health Technology R&D Project of the Korea Health Industry Development Institute (KHIDI), Funded by the Ministry of Health and Welfare, Republic of Korea (grant number: HI20C0056) and a National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT; No. NRF-2020R1F1A1052024).