Understanding how living systems repair and renew themselves underpins much of modern tissue engineering. Biological models of regeneration examine how species such as salamanders, zebrafish, and planarians naturally regrow limbs, spinal tissue, or entire organs. These models reveal key molecular pathways—such as Wnt, BMP, and FGF signaling—that are conserved across species and can be manipulated in human cells for therapeutic purposes. By studying cellular plasticity, immune modulation, and scaffold-independent regeneration, researchers identify principles applicable to human healing. Biological models of regeneration inform the design of synthetic systems, gene circuits, and scaffold-free regeneration strategies, bringing biologically inspired insights into clinical frameworks and strengthening the foundation for transformative therapies.