Small Peptide Functionalized Thiol-Ene Hydrogels as Culture Substrates for Understanding Valvular Interstitial Cell Activation and de novo Tissue Deposition

摘要

A thiol-ene polymerization platform was used to synthesize peptide functionalized poly(ethylene glycol) (PEG) hydrogels, which were initially characterized and compared to theoretical predictions of Young’s modulus via a theoretical crosslinking density equation presented herein. After thorough characterization, this material system’s utility for answering specific biological hypotheses was demonstrated with the culture and observation of aortic valvular interstitial cells (VICs). Specifically, these materials were used to better understand the role of substrate elasticity and biochemical functionality on VIC α-smooth muscle (αSMA) expression and secretory properties (i.e., de novo ECM). The Young’s moduli of the hydrogels were varied from 28kPa (activating, 90% myofibroblasts) to 4kPa (non-activating, 15% myofibroblast) substrates, and the biochemical functionality was tailored by incorporating three small adhesive peptide sequences, RGDS, VGVAPG, and P15. To promote VIC adhesion, a basal [RGDS] of 0.8mM was used in all formulations, while the [VGVAPG] or [P15] were varied to be lower, equal, or higher than 0.8mM. The substrates with 1.2mM VGVAPG and all gels with P15 led to significantly higher αSMA expression for both stiff and soft substrates, as compared to 0.8mM RGDS alone. Importantly, all gel conditions were significantly lower than TCPS (~4–10 fold difference). The ECM produced significantly decreased as the total integrin binding peptide concentration increased, but was significantly higher than that expressed on TCPS. This easily tailored material system provides a useful culture platform to improve the fundamental understanding of VIC biology through isolating specific biological cues and observing VIC function.