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RNA innate immunity constitutes a barrier for interspecies chimerism
Journal article   Peer reviewed

RNA innate immunity constitutes a barrier for interspecies chimerism

Yingying Hu, Hai-Xi Sun, Masahiro Sakurai, Zhou Luo, Amanda E. Jones, Tianlei Cheng, Jia Huang, Lizhong Liu, Canbin Zheng, Jie Li, …
Cell, Vol.189(1), pp.23-33.e16
01/08/2026
DOI: 10.1016/j.cell.2025.10.039
PMCID: PMC13008183
PMID: 41289993

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Abstract

Creating interspecies chimeras with human pluripotent stem cells (hPSCs) offers a promising strategy for modeling human development and generating donor organs; however, poor human cell integration remains a major barrier. Most existing efforts to improve human chimerism focus on genetically modifying donor hPSCs, while altering the host embryo remains largely unexplored. Using an interspecies PSC competition model, we discovered that RNA innate immunity in “winner” mouse cells drives the competitive elimination of hPSCs. Disrupting RNA-sensing pathways reduced the competitiveness and viability of mouse PSCs, and mouse embryos lacking Mavs—a key gene in RNA innate immunity—led to markedly improved human cell survival and chimerism. We also found that contact-dependent horizontal RNA transfer likely underlies this immune activation. Overall, our study uncovers a previously unrecognized role for RNA innate immunity in cell competition and demonstrates that targeting host immune pathways represents a powerful approach to improve human chimerism in animals. [Display omitted] •Co-culture with human PSCs triggers the RNA innate immune response in mouse PSCs•Mavs knockout weakens the mouse PSCs’ competitiveness and improves human PSC survival•Mavs-deficient mouse embryos boost human PSC survival and chimerism in vivo•Interspecies PSC co-culture enables direct, contact-dependent horizontal RNA transfer Interspecies PSC co-culture induces horizontal RNA transfer that activates innate immunity in “winner” mouse cells, a response that is alleviated by Mavs deletion, thereby enhancing “loser” human PSC survival and chimerism.
cell competition horizontal RNA transfer human pluripotent stem cells interspecies chimeras interspecies PSC co-culture MAVS mouse epiblast stem cells RLR pathway RNA innate immunity tunneling nanotube

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