An Enzyme-Cleavable Cage on Integrin Adhesive Ligand Regulates Stem Cell Fate in An External Stimulus-Free Manner

The interaction between integrins and their receptors is essential for cell adhesion, acting as a critical link for cells to sense and respond to signals from the extracellular matrix (ECM). While various stimuli-responsive systems, such as electrical, optical, enzymatic, and magnetic systems, have been employed to modulate the binding of arginine-glycine-aspartic acid (RGD) to integrins, these triggers often pose risks of cellular damage. Here, the cRGD ligands are passivated by conjugating amide cages with varying electron densities on the side chain of aspartic acid in cRGD peptides in order to undergo spontaneous hydrolysis of the cages via MSC exocrine enzymes during cell adhesion. This modification allows precise control over enzyme-mediated cage degradation and cRGD activation as the varying electron densities affect the stability of the amide cages. Our approach enables controllable spatiotemporal integrin activation, thereby regulating cell spreading and differentiation while minimizing the risks associated with external stimuli.