Scientists have discovered a method of helping human stem cells thrive in an animal embryo—a key development in efforts to grow human organs in animals for medical transplants.
A study by UT Southwestern found that turning off a specific gene in mouse cells weakens their competitive advantage over human cells, dramatically improving integration of human cells in a chimeric embryo—an organism containing cells from multiple species. The study was published in Cell.
“The findings provide insights for enhancing human-animal chimerism without altering donor human cells,” said Dr. Jun Wu, a molecular biologist at UT Southwestern. “This advances the possibility of growing human organs in animal hosts and potentially easing the global shortage of transplantable organs.”
Normally, mouse cells outcompete human stem cells, limiting the ability to create chimeric embryos. Researchers found that mouse cells do this by activating an RNA-based immune defense, known as RNA innate immunity, whenever foreign human RNA enters the cell. This immune response suppresses human cells, giving mouse cells a competitive advantage.
By disabling a gene called MAVS in the mouse cells, researchers turned off this immune alarm, reducing the competitiveness of mouse cells and allowing human stem cells to survive and integrate more effectively. This increased the level of “chimerism,” the coexistence of cells from two species in a single embryo.
While still in early-stage laboratory embryos, Dr. Wu said the findings reveal a barrier to interspecies stem cell integration and suggest a promising strategy for advancing human organ growth in animals.