Researchers have generated farm animals with integrated gene scissors, which can be used for genome editing in biomedical and agricultural science.
Chicken and pigs are among the most important livestock species in the world. They are both food sources and valuable models for evolutionary biology and biomedical science. Pigs share a high anatomical and physiological similarity with humans. They are also important for translational biomedical research, such as in cancer and cardiovascular disease. In addition, pig models resemble human pathophenotype more closely than other model organisms like rodents. While chickens are phylogenetically distant vertebrates from humans, they have been instrumental in the understanding of development.
Genetically modifying livestock species is a promising approach for agriculture, providing new opportunities for disease control. However, due to the lack of fully functional embryonic stem cells, genetically engineering pigs and chickens is currently an inefficient and time-consuming procedure. The advent of synthetic endonucleases, such as CRISPR-Cas9, has improved targeted germline modification in both species. Yet, this process still requires the generation and breeding of new founder lines.
Generation of transgenic animals with gene scissors
In this study, published in PNAS, researchers attempted to circumvent current limitations by generating transgenic chicken and pigs that constitutively and ubiquitously express Cas9. Consequently, these animals only require the delivery of the respective guide RNA to get animals with specific genetic characteristics.
The team found that all chickens and pigs that possessed the Cas9 nuclease were healthy. They also confirmed the functionality of Cas9 in both these species for a number of different target genes and cell types.
Overall, these Cas9 transgenic animals provide a powerful resource for in vivo genome editing that will have applications in both agricultural and translational biomedical research.
Angelika Schnieke, Professor of Livestock Biotechnology at the Technical University of Munich, stated:
“Due to the presence of Cas9 in the cells the processes are significantly accelerated and simplified.
Cas9-equipped animals make it possible, for example, to specifically inactivate tumour-relevant genes and to simulate cancer development.”
Image credit: By Design Cells – canva.com