Genome editing in large animals: current status and future prospects

Abstract

Large animals (non-human primates, livestock and dogs) are playing important roles in biomedical research, and large livestock animals serve as important sources of meat and milk. The recently developed programmable DNA nucleases have revolutionized the generation of gene-modified large animals that are used for biological and biomedical research. In this review, we briefly introduce the recent advances in nuclease-meditated gene editing tools, and we outline these editing tools' applications in human disease modeling, regenerative medicine and agriculture. Additionally, we provide perspectives regarding the challenges and prospects of the new genome editing technology.

Keywords: agriculture; disease model; genome editing; large animal; xenotransplantation.

Figure 1.

Major strategies to recruit DNA- and RNA-targeting and modifying enzymes via the CRISPR/Cas systems, and their potential applications in large animals to life science fields. Left panel: large animals including pig, cow, sheep, monkey and dog are discussed in this review. Middle panel: CRISPR-based technologies have been developed to edit DNA and RNA, and regulate transcription. Right panel: potential applications of genome-edited large animals in modeling human diseases, offering xenotransplant organs, livestock breeding and more.

Figure 2.

Disease models using large animals contribute to basic science as well as translational science research. Nuclease-mediated genome editing can introduce specific mutations into orthologous genes in large animals, including NHPs, pigs and dogs. Large animal disease models contribute to our fundamental understanding of the underlying mechanisms of disease and, therefore, therapeutic development to treat or cure human disease.

Figure 3.

Strategies to manipulating pig organs to make them compatible to humans. Left panel: genetically modified pigs could provide organs compatible with the human immune system (e.g. GGTA1, CMAH knockout, hCD46, hCD55 and hCD59 transgenic) and free of PERV. Right panel: hESCs or iPSCs were injected into genetically modified pig embryos that lacked specific tissues or organs, generating human organs in the human–pig chimeras.

Figure 4.

CRISPR/Cas system-mediated genome editing in farm animals has created a new era of breeding by design. Left panel: suiforme diversity and phylogenetic relationship of Sus scrofa. With the power of natural selection, S. scrofa, S. salvanlus et al. evolved from the same ancestor [156]. Pig pictures are adapted from the animal diversity website at the University of Michigan Museum of Zoology. Middle panel: driven by artificial selection, including index selection, best linear unbiased prediction (BLUP), marker-assisted selection (MAS) and whole-genome selection, pig breeds with advanced production ability (Doruc, Landrace and Large white), miniaturized body (Tibet, Wuzhishan and Bama) and high prolificacy (Taihu) were created. Right panel: with the aid of CRISPR/Cas-mediated genome editing, functional genes or loci from viruses, bacteria, worms, plants and other elite animals are able to be introduced into livestock for designed traits. Evidence is presented for the feasibility of breeding by design, such as thermoregulation, meat quality, disease resistance and livestock production. Breeding mediated by genome editing dramatically improves the spectrum for making genetic modifications in livestock, and reduces the costs and timeframes for generating desired mutant animals.