|LAUGHLIN, TAYLOR - University Of Nebraska|
|PANNIER, ANGELA - University Of Nebraska|
Submitted to: Reproduction, Fertility and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2017
Publication Date: 12/1/2017
Citation: Laughlin, T.D., Miles, J.R., Wright-Johnson, E.C., Rempel, L.A., Lents, C.A., Pannier, A.K. 2017. Development of pre-implantation porcine blastocysts cultured within alginate hydrogel systems either supplemented with secreted phosphoprotein 1 or conjugated with Arg-Gly-Asp Peptide. Reproduction, Fertility and Development. 29(12):2345-2356. https://doi.org/10.1071/RD16366.
Interpretive Summary: The majority of early embryonic mortality in the pig is primarily influenced by deficiencies in embryo elongation. Many uterine specific factors, like secreted phosphoprotein 1 (SPP1) with its integrin binding Arg-Gly-Asp (RGD) peptide, are thought to play a role in the development of pre-implantation embryo; however, the exact mechanisms are not known partly due to inadequate culture system capable to replicate this process in vitro. The objective of the current study was to expand our established alginate hydrogel culture system and evaluate embryo development of pre-implantation porcine embryos encapsulated and cultured within alginate hydrogels either supplemented with SPP1 or conjugated with RGD. This study demonstrated that embryos encapsulated in alginate hydrogels with the integrin binging RGD sequence led to increased embryonic survival, improved changes in morphology and modulation of gene expression support of increased secretion of estradiol-17'; thereby, illustrating the importance of the integrin RGD peptide sequence for stimulating the initiation of embryo elongation.
Technical Abstract: Although deficiencies in porcine blastocyst elongation play a significant role in early embryonic mortality and establishment of within-litter developmental variation, the exact mechanisms of elongation are poorly understood. Secreted phosphoprotein 1 (SPP1) is increased within the uterine milieu during early porcine pregnancy and contains an Arg-Gly-Asp (RGD) peptide sequence that binds to cell surface integrins on the uterine endometrium and trophectoderm, promoting cell adhesion and migration. The aim of the present study was to evaluate the development of preimplantation porcine blastocysts encapsulated and cultured within alginate hydrogels either supplemented with SPP1 or conjugated with RGD. Blastocysts encapsulated within alginate hydrogels supplemented with SPP1 or conjugated with RGD had increased survival compared with non-encapsulated control blastocysts. In addition, the percentage of blastocysts encapsulated within RGD hydrogels that underwent morphological changes was greater than that of blastocysts encapsulated within standard alginate hydrogels or SPP1-supplemented hydrogels. Finally, only blastocysts encapsulated within RGD hydrogels had both increased expression of steroidogenic and immune responsiveness transcripts and increased 17ß-oestradiol production, consistent with blastocysts undergoing elongation in vivo. These results illustrate the importance of the integrin-binding RGD peptide sequence for stimulating the initiation of blastocyst elongation.