Efficient gene editing of pig embryos by combining electroporation and lipofection.

Background and Aim: Mosaicism, which is characterized by the presence of wild-type and more than one mutant allele, poses a serious problem in zygotic gene modification through the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 system. Therefore, we used pig embryos to compare the gene editing efficiencies achieved by combining electroporation and lipofection using different aminopeptidase N (APN)-targeting guide RNA (gRNA) sequences. Materials and Methods: Six gRNAs (gRNA1-6) with different target sequences were designed to target APN. Results: gRNA4 and gRNA6 exhibited the lowest and highest mutation rates, respectively. gRNA4-targeted ZP-free embryos subjected to additional lipofection 29 h after IVF initiation exhibited significantly higher total and biallelic mutation rates than ZP-intact embryos that received only electroporation. Additional lipofection of gRNA6-targeted embryos had no obvious effect on mutation rates. Conclusion: Electroporation combined with lipofection using gRNAs with low mutation rates may improve gene editing efficiency in pig embryos. However, the effects may vary based on the timing of gene editing.