Fundamental insight into the effect of carbodiimide crosslinking on cellular recognition of collagen-based scaffolds

Abstract

Research on the development of collagen constructs is extremely important in the field of tissue engineering. Collagen scaffolds for numerous tissue engineering applications are frequently crosslinked with 1-ethyl-3-(3-dimethylaminopropyl-carbodiimide hydrochloride (EDC) in the presence of N-hydroxy-succinimide (NHS). Despite producing scaffolds with good biocompatibility and low cellular toxicity the influence of EDC/NHS crosslinking on the cell interactive properties of collagen has been overlooked. Here we have extensively studied the interaction of model cell lines with collagen I-based materials after crosslinking with different ratios of EDC in relation to the number of carboxylic acid residues on collagen. Divalent cation-dependent cell adhesion, via integrins α${1}$β${1}$, α${2}$β${1}$, α${10}$β${1}$ and α${11}$β${1}$, were sensitive to EDC crosslinking. With increasing EDC concentration, this was replaced with cation-independent adhesion. These results were replicated using purified recombinant I domains derived from integrin α${1}$ and α${2}$ subunits. Integrin α${2}$β${1}$-mediated cell spreading, apoptosis and proliferation were all heavily influenced by EDC crosslinking of collagen. Data from this rigorous study provides an exciting new insight that EDC/NHS crosslinking is utilising the same carboxylic side chain chemistry that is vital for native-like integrin-mediated cell interactions. Due to the ubiquitous usage of EDC/NHS crosslinked collagen for biomaterials fabrication this data is essential to have a full understanding in order to ensure optimized collagen-based material performance.