Mechanical characterisation of a customised decellularized scaffold for vascular tissue engineering

Abstract

Several challenges persist when attempting to utilise decellularized tissue as a scaffold for vascular tissue engineering. Namely: poor cell infiltration/migration, excessive culture times associated with repopulating the scaffolds, and the achievement of a quiescent medial layer. In an attempt to create an optimum vascular scaffold we customised the properties of decellularized porcine carotid arteries by: (i) creating cavities within the medial layer to allow direct injection of cells, and (ii) controlling the amount of collagen digestion to increase the porosity. Histological examination of our customised scaffold revealed a highly porous tissue structure containing consistent medial cavities running longitudinally through the porous scaffold wall. Mechanical testing of the customised scaffold showed that our minimal localised disruption to the ECM does not have a detrimental effect on the bulk mechanical response of the tissue. The results demonstrate that an increased stiffness and reduced distensibility occurs after decellularisation when compared to native tissue, however post scaffold customisation we can revert the scaffold tensile properties back to that of native tissue. This most noteworthy result occurs in the elastin dominant phase of the tensile response of the scaffold, indicating no disruption has occurred to the elastin network by our decellularization and customisation techniques. Additionally, the bulk seeding potential of the customised scaffold was demonstrated by direct injection of human smooth muscle cells through the medial cavities. The optimum cell dispersion was observed in the highest porosity scaffold, with large cell numbers retained within the medial layer after 24 h static culture. In summary, this study presents a novel customised decellularized vascular scaffold that has the capability of bulk seeding the media, and in tandem to this method the porosity of the scaffold has been increased without compromising the mechanical integrity.