Prototissues: Assembly strategies, collective behaviors, and emerging applications.

Recent advances in bottom-up synthetic biology have significantly expanded the ability to construct artificial life systems. While most efforts focus on building protocells, many biomimetic functions arise only when multiple units operate collectively. Prototissues, formed from interconnected protocell assemblies, provide a platform for such emergent behaviors and offer broad potential in biomedicine, biosensing, and smart materials. This review introduces a dual-dimensional framework for understanding prototissue design. The first dimension examines inter-protocell adhesion strategies that define molecular connectivity, and the second examines spatial programming approaches that organize protocells into functional architectures. On this basis, the review summarizes key collective behaviors enabled by these design principles and highlights how advances in materials chemistry, synthetic biology, and advanced manufacturing support the development of increasingly adaptive and functional prototissues. Major challenges remain, including achieving dynamic and selective adhesion, scaling spatial architectures while maintaining resolution, improving signal transport, and enhancing biological integration. The review outlines potential pathways to address these issues and to guide the development of prototissues with more sophisticated, life-like properties. Overall, the conceptual framework and insights presented here provide a foundation for the rational design of next-generation prototissues and advance bottom-up synthetic biology toward more complex artificial life systems.