Scientists create gene-edited livestock surrogate sires fertile

For the first time, scientists have created pigs, goats and cattle that can serve as viable ‘surrogate sires’

In a recent study by a research team led by Oatley used the gene-editing tool, CRISPR-Cas9, to knock out a gene-specific to male fertility in the animal embryos that would be raised to become surrogate sires. The male animals were then born sterile but began producing sperm after researchers transplanted stem cells from donor animals into their testes. The sperm the surrogate sires produced held only the genetic material of the selected donor animals. The gene-editing process employed in this study seeks to bring about changes within an animal species that could occur naturally, such as infertility.

The study is the result of six years of collaborative work among researchers at WSU, Utah State University, University of Maryland and the Roslin Institute at the University of Edinburgh in the U.K.

The researchers used CRISPR-Cas9 to produce mice, pigs, goats and cattle that lacked a gene called NANOS2 which is specific to male fertility. The male animals grew up sterile but otherwise healthy, so when they received transplanted sperm-producing stem cells from other animals, they started producing sperm derived from the donor’s cells.

The surrogate sires were confirmed to have active donor sperm. The surrogate mice fathered healthy offspring who carried the genes of the donor mice. The larger animals have not been bred yet. Oatley’s lab is refining the stem cell transplantation process before taking that next step.

Oatley realizes there is a lot of work to do outside of the lab and recently joined the National Task Force on Gene Editing in Livestock to bring together researchers, industry representatives, bioethicists and policymakers to find a path forward for the technology.