Fabrication of fibrillated and interconnected porous poly(ε-caprolactone) vascular tissue engineering scaffolds by microcellular foaming and polymer leaching

This paper provides a method combining eco-friendly supercritical CO2 microcellular foaming and polymer leaching to fabricate small-diameter vascular tissue engineering scaffolds. The relationship between pore morphology and mechanical properties, and the cytocompatibility, are investigated with respect to the effects of poly(epsilon-caprolactone)/poly(ethylene oxide) (PCL/PEO) phase morphologies and PEO leaching. When PEO content increases, the pore size decreases and the pore density increases. After the leaching process, highly interconnected and fibrillated porous structures are detected in the foamed PCL70 blend with droplet-matrix morphologies. Moreover, the leaching process had a greater contribution to improve the open-cell content in the PCL50 blend, which has a co-continuous morphology and easily obtained open-cell content of more than 80%. Small-diameter tubular PCL70 and PCL50 porous scaffolds with an average pore size of 48 +/- 1.4 mu m and 30 +/- 1.0 mu m respectively, are fabricated successfully. Prominent orientated pores are found in the PCL70 scaffold, and a mixed microstructure combining interconnected channels and open cells occurs in PCL50 scaffold. The PCL70 scaffold has a greater longitudinal tensile strength, longer toe region, and larger cyclical recoverability. HUVECs tend to align along the direction of the pore orientation in the PCL70 scaffold, whereas HUVECs have a higher density and spreading area in the PCL50 scaffold. The results gathered in this paper may provide a theoretical basis and data support for fabricating small-diameter porous tissue engineering vascular scaffolds.