Effect of various co-culture systems on embryo development in ovine

Considering the advent of mesenchymal stem cells (MSCs) as a new source of somatic cells in embryo co-culture system, the current study was aimed to compare in vitro embryo development using embryonic MSCs monolayer with embryonic fibroblast cells (EFCs), oviductal epithelial cells (OECs), and cell-free culture system. The IVM/IVF presumptive sheep zygotes were randomly cultured in different culture conditions as follows: (1) SOFaaBSA medium for the whole culture period (SOP, n = 371), (2) SOFaaBSA medium for the first 3 days followed by co-culturing with MSCs for the next 5 days (SOF-MSCs, n = 120), (3) co-culturing with MSCs for the first 3 days followed by culture in SOFaaBSA medium for the next 5 days (MSCs-SOF, n = 133), (4) co-culturing with MSCs for the whole culture period (MSCs, n = 212), (5) SOFaaBSA medium for the first 3 days followed by co-culturing with EFCs for the next 5 days (SOP-EFCs, n = 132), (6) co-culturing with EFCs for the first 3 days followed by culture in SOFaaBSA medium for the next 5 days (EFCs-SOF, n = 165), (7) co-culturing with EFCs for the whole culture period (EFCs, n = 236), and (8) co-culturing with OECs for the whole culture period (OECs, n = 255). One-Way ANOVA by multiple pairwise comparisons using Tukey's test was performed. Co-culturing in MSCs group had no superiority over EFCs and OECs groups. Though, when co-culturing with MSCs and EFCs was limited to the first 3 days of culture, the embryo development indices were improved compared to the other co-cultured groups. Considering both the hatching rate and total cell number, the application of MSCs for the first 3 days of culture (MSCs-SOP) was superior to the other co-culture and SOP groups.