Magnetic Cell Assembly for Engineering Living Building Blocks: Principles, Strategies, and Biomedical Applications

Magnetic cell assembly has emerged as a powerful biofabrication strategy that uses externally applied magnetic fields to manipulate and organize living cells with spatial control, enabling the fabrication of scaffold-free multicellular constructs while preserving cell viability and function. Advances in magnetic nanoparticles, cell labeling techniques, and magnetic field engineering have expanded its applications from rapid spheroid formation to the assembly of complex, spatially organized tissues. This review provides a comprehensive overview of the fundamental principles governing magnetic cell assembly, including the generation of magnetically responsive cells, magnetic force-mediated manipulation, and the biological processes driving tissue formation after magnetic assembly. We discuss the major assembly strategies, including magnetic aggregation, levitation, patterning, alignment, and modular tissue assembly, highlighting their underlying mechanisms, representative studies, engineering advantages, and current limitations. Recent progress in musculoskeletal, cardiovascular, neural, and vascular tissue engineering, as well as organoid and assembloid technologies, disease modeling, and drug discovery, is critically evaluated with an emphasis on experimental outcomes and remaining challenges. Particular attention is given to how magnetic cell assembly has evolved from a technique for manipulating individual cells into a programmable platform for organizing living building blocks with increasing structural and biological complexity. Finally, we discuss the key obstacles to clinical translation, including vascularization, tissue maturation, scalability, reproducibility, and standardization, together with future opportunities arising from the integration of magnetic cell assembly with bioprinting, stem cell engineering, microphysiological systems, and artificial intelligence. This review highlights the potential of magnetic cell assembly as an enabling technology that bridges magnetism and biofabrication to engineer next-generation living tissue models.