Engineering Livestock Stem Cells: New Tools for Functional Biology and Disease Research

Access to biologically relevant cell models remains a challenge for livestock research. Many experiments rely on primary cells isolated directly from animals. These cells can have a limited lifespan in culture, and obtaining enough for experiments may require repeated collection from multiple animals, introducing biological variability as well as increasing animal use.

Induced pluripotent stem cells (iPSCs) offer an alternative. iPSCs are generated by reprogramming mature cells into a pluripotent state. They can self-renew and give rise to many specialised cell types, providing a renewable source of genetically defined cells. However, maintaining livestock cells in a stable pluripotent state has historically been challenging.

Engineering control of pluripotency in livestock cells

Researchers at the Roslin Institute have introduced a controllable transgenic system into cells to maintain their pluripotent state. The system contains genes encoding pluripotency factors that can be switched on or off. These factors regulate networks of genes that keep the cells in a pluripotent, self-renewing state. 

When the system is switched on, the transgene-regulated iPSCs can be maintained and expanded in culture. When it is switched off, the cells can leave the pluripotent state and, using specific culture conditions, be directed to differentiate into specialised cell types such as macrophages.

This creates a renewable and genetically tractable platform in which cells with defined genetic backgrounds can be expanded, genetically modified, differentiated and compared under controlled conditions.

Putting the platform to work: comparing ASFV responses across pig species

African swine fever virus (ASFV) primarily infects macrophages and causes severe disease with very high mortality in domestic pigs and wild boar. In contrast, natural African hosts such as warthogs can become infected without developing severe disease. Understanding the biological basis of these differences could reveal mechanisms associated with disease susceptibility or resilience.

Researchers generated transgene-regulated iPSC lines from four members of the pig family: domestic pig, wild boar, red river hog and warthog. The iPSC lines from these different species were subsequently differentiated into macrophages.

Macrophages derived from all four iPSC lines could be infected with ASFV and supported viral replication, demonstrating that the engineered cells can provide a relevant model for studying infection. However, the cellular response to infection differed between species. Only warthog iPSC-derived macrophages failed to induce interferon-alpha, an antiviral signalling protein produced as part of the immune response to infection.

This species-specific difference in macrophage response can now be investigated further to identify mechanisms underlying disease susceptibility and resilience and potentially inform strategies to mitigate ASFV in domestic pigs.

From cellular models to functional genetics

The wider value of the approach extends beyond ASFV. Combining engineered livestock iPSCs with genome-editing technologies provides a platform in which candidate genes can be identified in vitro, manipulated, and functionally tested in relevant differentiated cell types.

This approach offers opportunities to:

• Identify and test candidate genes in vitro, accelerating the discovery of genes and pathways underlying important traits.
• Engineer defined genetic changes and directly investigate their effects on cell function.
• Compare responses across genetic backgrounds and species under controlled experimental conditions.
• Generate different specialised cell types from renewable iPSC lines for a range of research applications.

• Reduce reliance on animals as a source of primary cells, while improving the consistency and scalability of experimental models.

   

A collaborative effort and specialist infrastructure

This research brought together expertise in stem cell biology, cell engineering, macrophage culture and African swine fever virology, alongside specialist high-containment facilities required for ASFV infection studies. Led by researchers at the Roslin Institute, the study involved collaborators at The Pirbright Institute, the Friedrich-Loeffler-Institut (FLI), the Animal and Plant Health Agency (APHA), the Royal Zoological Society of Scotland and Roslin Technologies.

Key publications

• Watson et al. Stem Cell Reports (2026). Suidae iPSC-derived macrophages as models for investigating susceptibility and resilience to African swine fever virus.
• Gao et al. Nature Cell Biology (2019). Establishment of porcine and human expanded potential stem cells.