Rapid stem cell spreading induced by high affinity α5β1 integrin-selective bicyclic RGD peptide in biomimetic hydrogels

Cell-matrix interactions form a crucial parameter for the design of a synthetic extracellular matrix (ECM), as they ultimately dictate cell fate and functions. Universally, synthetic biomaterials are conjugated with a linear or cyclic Arg-Gly-Asp (RGD) peptide to establish a direct link of the ECM with the cell. These peptides, however, present low binding affinities and lack selectivity towards integrin subtypes presented on the cell membrane. Here, a highly biomimetic synthetic ECM based on polyisocyanides (PIC) that has been decorated with bicyclic peptides that show a high affinity towards specific integrin subtypes is presented. 3D cell studies show that human adipose-derived stem cells (hASCs) in matrices carrying the optimized bicyclic α5β1-integrin binder, spread within 24 hours, which is much faster than in other PIC gels, including the default RGD-decorated gel, but also much faster than in the positive Matrigel control. YAP/TAZ staining shows that the rapid morphological change in the 3D microenvironments is YAP independent. The data highlights that the design of synthetic matrices with appropriate, optimized guiding signals is key to guide cells towards a predetermined outcome. ### Competing Interest Statement The authors have declared no competing interest.