The Impact of Novel Sterilisation Methods on the Biological and Biomechanical Properties of Decellularised Heart Valves

Valvular heart disease has a major impact on patient morbidity and mortality on a global scale. Current heart valve replacement options present with numerous limitations. These can be addressed by the implementation of a novel decellularised heart valve replacement option that can meet clinical needs. However, decellularised heart valves require sterilisation prior to clinical use.
The aim of this study was to identify a novel sterilisation method that minimally impacts ECM structure and components, biochemical composition,
biocompatibility, and biomechanical properties of decellularised porcine pulmonary heart valves (dPHVs).
Sterilisation of dPHVs with 1 mg/L copper chloride (CuCl2) combined with 1 % hydrogen peroxide (H2O2) (pH 7) for 3 hours at 37 °C resulted in histoarchitectural alterations of the leaflets, a reduction in collagen thermal stability and a loss of tissue mechanical strength. However, the intensity of collagen IV and fibronectin
immunolabelling was comparable to untreated dPHV tissue.
Supercritical carbon dioxide (ScCO2) sterilisation (supplemented with 13.5 - 18.5 % [v/v] PAA and 4.5 - 6 % [v/v] H2O2) of dPHVs in Poly-Tyvek pouches resulted in the unanticipated compression of the whole dPHV macroscopic structure. ScCO2 treatment of dPHVs in Poly-Tyvek pouches and dPHVs submerged in PBS resulted in a significant reduction in collagen IV immunolabelling and a reduction in collagen thermal stability in comparison to untreated dPHV controls. However, fibronectin immunolabelling was retained along with the ECM histoarchitecture, biochemical composition and tissue biomechanical properties.ScCO2 sterilisation of dPHVs submerged in PBS did not detrimentally impact valve competency, expansion characteristics and suture retention properties in comparison to untreated dPHV controls. In vitro contact and extract cytotoxicity assessments demonstrated that both sterilisation methods investigated did not induce a cytotoxic response.
Overall, ScCO2 sterilisation under submerged conditions may be the optimalmethod for the terminal sterilisation of dPHVs.