Alginate/Gelatin Hydrogels to Coat Porous Tubular Scaffolds for Vascular Tissue Engineering

To perfuse porous tubular scaffolds for vascular tissue engineering (VTE) with a controlled flow rate, there is the need to prevent leakage from the scaffold lumen. A gel coating made of 8% w/v alginate and 6% w/v gelatin, at different volumetric proportions (50/50, 70/30 and 90/10), functionalized with fibronectin, was produced using a custom-made bioreactor-based method. Gel swelling and stability, and rheological and uniaxial stretch tests on different percentages of alginate and gelatin demonstrate the gel ability to resist to biochemical microenvironment, to well withstand physiological deformations (~10%) and wall shear stresses (5-20 dyne/cm2). These are prerequisites to stimulate tubular scaffolds with the proper mechanical stimuli able to maintain the physiological phenotype of vascular smooth muscle cells and endothelial cells (ECs), as in blood vessels. Cytocompatibility shows gel capability to induce ECs proliferation and colonization within the gel, especially in presence of fibronectin and higher gelatin percentage. The custom-designed bioreactor is suitable to create reproducible and homogeneous tubular gel coating, independently from alginate percentage. Permeability test shows the effectiveness of 70/30 alginate/gelatin gel to occlude wadding pores, and therefore prevent leakages. In this regard, the synthetized tubular alginate/gelatin gel with fibronectin represents a promising substrate for ECs, as well as leakproof when the scaffold is submitted to pulsatile perfusion for VTE applications.