The embryo game uncovers hidden cell behaviours

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Cell Biology

Background:

• Cells prioritize survival but must cooperate for successful embryo development.
• Cell competition, a conserved cell-killing mechanism, is hypothesized to correct embryonic errors.
• Direct links between cell competition and overall embryo success remain under-explored.

Purpose of the Study:

• To investigate how cellular behaviors, specifically cell competition, influence human embryonic development.
• To integrate evolutionary game theory with in vitro embryo modeling to understand cell cooperation.

Main Methods:

• Developed a collective risk game model to analyze the costs and benefits of cell killing.
• Utilized in vitro embryoid models to observe cellular behaviors during development.
• Manipulated cell death pathways to assess their impact on embryoid size and viability.

Main Results:

• The game model indicated that cell killing is beneficial when embryos exceed target size and survival probability is low.
• In vitro embryoids successfully formed within the target size range of native human embryonic discs.
• Inhibiting cell death resulted in larger, defective embryoids, demonstrating the role of cell killing in size regulation.
• Cell killing and proliferation were identified as responsive behaviors maintaining optimal embryoid size.

Conclusions:

• Conditional cell killing acts as a "threat" to regulate over-proliferating cells, promoting cooperation.
• Cell competition may be a crucial mechanism underpinning cooperative behaviors essential for successful embryogenesis.
• This study provides novel insights into the paradoxical role of cell death in supporting collective embryonic development.