108 Effect of sericin supplementation in IVM-in vitro culture medium and vitrification of bovine in vitro-produced embryos
J. Velasquez Vasquez A , M. Betancur Restrepo A , O. Velasquez Arboleda A , J. Montoya Paez A , J. Gomez Oquendo A , G. Restrepo Betancur B and M. Duque Rodriguez AA Grupo de Investigación en Biotecnología Animal, Facultad de Ciencias Agrarias, Politécnico Colombiano Jaime Isaza Cadavid, Medellín, Antioquia, Colombia
B Faculty of Agricultural Sciences, Universidad Nacional de Colombia, Medellín, Antioquia, Colombia
Reproduction, Fertility and Development 35(2) 181-181 https://doi.org/10.1071/RDv35n2Ab108
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
Fetal bovine serum (FBS) has been widely used as a media supplementation of in vitro embryo production (IVEP), since it provides growth factors, hormones, amino acids, and proteins that are beneficial for embryonic development. However, several studies have reported that embryos produced in vivo are less sensitive to cryopreservation than those produced in vitro. The reduced resistance of IVEP to cryopreservation can be partially attributed to the effects of some components of the in vitro culture (IVC) medium, especially FBS. The objective of this study was to investigate the effect of sericin supplementation, a sticky protein derived from the silkworm (Bombyx mori) silk, during in vitro maturation (IVM) and IVC, as an alternative replacement for FBS. We evaluated the effect on embryo development and post-vitrification survival. Bovine serum albumin (BSA), FBS, and the absence of a protein source (w/oPS) were also evaluated. Slaughterhouse-derived bovine oocytes were in vitro matured for 22–24 h in tissue culture medium 199, supplemented with 0.2 mM sodium pyruvate, 10 ug/mL FSH, 100 uM cysteamine, 0.5% ATB, and 1% sericin at 38.5°C in 6.5% CO2 humidified air. 10% FBS and 0.6% BSA were used for control groups as a replacement of sericin in IVM medium. For IVF, in vitro-matured oocytes were co-incubated with 2 × 106 spermatozoa per mL in an atmosphere of 21% O2 at 38.5°C in 6.5% CO2 humidified air for 18–20 h. Presumptive zygotes were cultured in vitro in 50-µL drops of synthetic oviducal fluid (SOF) medium supplemented with 1% of sericin on 6.5% CO2 in the air at 38.5°C. 5% FBS and 0.6% BSA were used for control groups as a replacement of sericin in IVC medium. Cleavage was determined 72 h post-fertilisation and blastocyst stage was evaluated at Day 7. Expanded blastocysts at Day 7 were vitrified and embryo re-expansion/hatching was evaluated 24–48 h post-warming. The experiment was repeated three times and data were analysed by Fisher’s exact test. No differences were observed between sericin (141/218, 64.6%) FBS (169/230, 73.4%), and BSA (138/225, 61.3%) groups in maturation and cleavage rate (155/235, 65.9%; 131/203, 64.5%; and 132/255, 51.7%, respectively). However, w/oPS showed lower maturation rates (94/201, 46.7%) compared with other groups. Additionally, we found that blastocyst rate was higher using FBS in comparison with other groups (38.5% vs 24.6%, 21.5% and 20.2%). Results regarding expansion and hatching of warmed embryos cultured for 24–48 h demonstrated that sericin and w/oPS had higher expansion (90%, 100% vs 30% and 60%) and hatching (50%, 38% vs 25% and 7%) rate compared with FBS and BSA. Our results suggest that supplementation with sericin in IVM and IVC medium increased cryotolerance and warming survival after vitrification. Further studies should be conducted to evaluate the implantation rate of vitrified-warmed embryos after transfer using sericin supplementation in IVM-IVC.
