RELEASE FROM BIODEGRADABLE BIO-HYBRID HYDROGEL AND ELECTROSTIMULATION: TOWARD A BIOMIMETIC ENVIRONMENT FOR ENDOTHELIAL CELLS

A number of biochemical, mechanical, electrical and topographical factors serve as cues to orchestrate cellular responses. Tissue and regenerative engineering seek conditions wherein cells are exposed to cues similar in magnitude and temporal profile to those found in-vivo. For this purpose, a biomimetic, hybrid, degradable, hydrogel scaffold has been developed for use in a novel instrument that enabled electrostimulation of and paracrine release to cells in culture. The hydrogel comprises HEMA and HPMA as synthetic components and methacrylated gelatin (GelMA) as natural, degradable component. Poly(HEMA-co-HPMA) hydrogels were studied for the influence of water content and distribution on key biotechnical properties. Poly(GelMA-coHEMA-co-HPMA) were synthesized with pre-loaded FITC-dextran 40kDa as growth factor surrogate. The GelMA content was varied (0-87 mol%) to tune its collagenase degradation. Hydrogel formulation and factor payload, guided by the application requirements of compression modulus, degradation rate, release profile of factor, and the availability of motifs for cellular attachment, yielded scaffolds suitable for cell attachment, growth and proliferation. An electrical cell stimulation and recording apparatus (ECSARA) equipped with in-situ electrical impedance spectroscopy (EIS) for real-time, non-invasive monitoring was developed to apply endogenous-range electric fields (EF) to cells in 3-D culture. The 24-well electroculture ware with trans-well Ti electrodes produced a uniform EF perpendicular to the plane of cells on porous, transwell inserts. The system produced stable, reproducible, well-to-well temporal responses. The effect of EF on HUVECs was monitored with viability assay and EIS. Results indicated accelerated proliferation (alamarBlue assay) and early onset tight junction formation (EIS) in response to EF