Tissue engineered vascular grafts: elastic polyethylene glycol hydrogel scaffolds for culture under pulsatile flow conditions

Increased demand for small diameter vascular grafts has spurred the development of scaffold materials for tissue engineered vascular grafts. We have investigated one such material, photopolymerizable polyethylene glycol (PEG) hydrogels. The mechanical properties of these PEG hydrogels may be tailored for a given application to provide desired elasticity and tensile strength. The Young´s modulus and ultimate tensile strength may be increased by increasing the polymer concentration, lowering the polymer molecular weight, or by combining a small fraction of low molecular weight polymer with a higher molecular weight polymer. Cells seeded within these PEG hydrogels retain viability throughout 4 weeks in culture, with no differences in viability across the thickness of the hydrogel. Tubular PEG hydrogel constructs were seeded with vascular smooth muscle cells and cultured under pulsatile flow conditions. After 4 days, the Young´s modulus and ultimate tensile strength of the constructs were significantly higher compared to static controls. Cells in the hydrogels also produced more extracellular matrix in pulsatile culture, as evidenced by hydroxyproline content, compared to static controls. These results suggest that PEG hydrogels may be suitable materials for vascular tissue engineering.