Receptor-mediated transport of foreign DNA into preimplantation mammalian embryos

Mouse and rabbit preimplantation embryos with intact zona pellucida were incubated for 3 hr with DNA‐carrying constructs containing insulin as an internalizable ligand: (insulin‐polylysine)‐DNA and (insulin‐polylysine)‐DNA‐(streptavidin‐polylysine)‐(biotinylated adenovirus). Video‐intensified microscopy demonstrated that the constructs penetrated the zona pellucida and accumulated in the blastomere perinuclear space. The percentage of blastocysts formed was about 70% after incubation of zygotes and two‐cell embryos with the constructs. Foreign DNA was detected after 51 hr in 80% of rabbit embryos and after 96 hr in 73% of mouse embryos. Inclusion of various adenoviruses into the construct improved foreign DNA preservation in early embryos. Blot hybridization revealed genome‐integrated foreign DNA in 12‐ and 15‐day mouse embryos and in a newborn. Thus, the ligand‐mediated mechanism can be employed for introducing foreign genetic material into early mammalian embryos; insulin provides for delivery inside the cell and to the nucleus, while adenoviruses ensure release from endosomes. Mol. Reprod. Dev. 54:112–120, 1999. © 1999 Wiley‐Liss, Inc.