Genetically programmable molecular framework for constructing precision recombinant human ECM mimics

Engineering extracellular matrix (ECM) mimetic materials that combine molecular precision of synthetic material options with native biological complexity remains a central challenge in biomaterials science. Here, we present a genetically programmable hydrogel platform that enables independent control of mechanical and biological properties including matrix composition, mechanics, viscoelasticity, and biochemical signaling using recombinant human ECM building blocks assembled via isopeptide chemistry. Modular protein ECM crosslinkers containing complete folded ECM domains equipped with terminal SpyTag peptides were integrated within SpyCatcher-functionalized interchangeable natural polysaccharide backbones to generate fully defined matrices with decoupled material parameters. Point mutations on crosslinker SpyTags within the bond interface varied bond affinity from covalent to physical bonding, allowing tuned stress-relaxation behaviors across physiologically relevant regimes without altering matrix composition nor stiffness. Using colorectal cancer models, we show that polymer identity and matrix viscoelasticity independently regulate spheroid growth, invasion capabilities, and dispersion. Importantly, recombinant ECM domains recapitulated native adhesion functions and provide a structurally encoded layer of biological information. This hydrogel platform provides a molecular framework for constructing precision recombinant human ECM mimics with broad applicability across biomaterials science, mechanobiology, disease modeling, tissue engineering, and regenerative medicine.