Since the development of the first genetically-modified mouse, transgenic animals have been utilized for a wide range of industrial applications as well as basic research. To date, these transgenic animals have been used in functional genomics studies, disease models, and therapeutic protein production. Recent advances in genome modification techniques such zinc finger nuclease (ZFN), transcription activator-like effector nucleases (TALEN), and clustered regularly interspaced short palindromic repeats (CRIPSR)-Cas9, have led to rapid advancement in the generation of genome-tailored livestock, as well as experimental animals; however, the development of genome-edited poultry has shown considerably slower progress compared to that seen in mammals. Here, we will focus primarily on the technical strategies for production of transgenic and gene-edited chickens, and their potential for future applications.

Germ cells originate outside of the fetal gonads and migrate toward the genital ridges through the embryonic tissue. Germ cell is the most important and valuable cell in livestock because germ cell is the only cell type that can transfer the genetic information and content into the next generation. In this study, we established the primordial germ cell (PGC) lines derived from the fetal gonads of 6 day-old-embryonic chicks, and then cryopreserved for long-term storage. First, we determined each chick embryo sex by genomic PCR with DNA extracted from blood. After dissociation of the whole gonads from individual embryos, total gonadal cells were plated into the culture dish and cultured with 20% fetal bovine serum-contained culture media. PGC lines were derived from three different chicken strains; White Leghorn (WL), Korean Oge (KO), and a commercial line, Hyline. There was no significant difference between the efficiencies of the PGC line derivation according to the different chicken strains. Thus, PGC culture and long-term storage system could be applied to maintain the endangered avian species and also produce the offspring through germline chimera production system.