Modulating Poly(ε-caprolactone) Scaffold Properties by Altering Porogen Concentration for Blood-Vessel Tissue Engineering

Abstract

Achievement of optimum scaffold porosity while bearing relevant mechanical integrity and suitable degradation profile needs to be addressed appropriately for the successful construction of a tissue engineered blood vessel. Poly[ethylene glycol] (PEG) was used as porogen while fabricating poly[ε-caprolactone] (PCL) tubular scaffolds by solvent casting and particulate leaching process. Scaffolds were fabricated by varying polymer/porogen ratio from 4:1, 2:1, 4:3 and 1:1 for comparative study. The effect of porogen concentration on scaffold physico-chemical properties including real time degradation in PBS at 37 °C was studied using two reference molecular weight PEGs (3400 and 8000). Wall thickness and tubular consistency of cast scaffolds were found to improve with increasing PEG content. Analysis using micro-computed tomography (μ-CT) revealed majority of pores to lie between 12–24 μm in size. The concentration of PEG was found to influence porosity, hydrophilicity, crystallinity and mechanical strength within scaffold systems containing each MW PEGs. Though considerable reduction in tensile strength was observed for scaffolds with 1:1 PCL:PEG ratio, mechanical integrity of these scaffolds were retained even after one year degradation. Scaffolds with 1:1 PEG-PCL ratio were found to have better structural integrity, highest porosity, favourable mechanical strength for blood vessel construction, long term degradation characteristics suitable for implant applications and good endothelial cell coverage after 3 days static cell culture.