In Vitro Biomechanical Evaluation Of Pre-implanted And Post-implanted Decellularised Porcine Pulmonary Valve Conduits
A Desai1, T Vafaee1, H E. Berry2, J Roderjan3, Costa da4, E Ingham1, J Fisher1.
1University of Leeds, Leeds, United Kingdom, 2University of Leeds & Tissue Regenix Ltd. The Biocentre, Innovation Way, York, United Kingdom, 3Pontificia Universidade Catolica do Parana (PUCPR), Curitiba, Parana, Brazil, 4Pontificia Universidade Catolica do Parana (PUCPR) & Santa Casa Misericordia Curitiba, Curitiba, Parana, Brazil.
OBJECTIVE: The aim of this study was to assess the effects of patented decellularisation and cryopreservation on the biomechanical properties of porcine pulmonary heart valve conduits (PHVC) pre- and 12 months post-implantation in sheep.
METHODS: Biomechanical properties of five PHVC groups were determined and compared to respective control groups (minimum n=4 for all) as follows: non-implanted cryopreserved decellularised porcine (DecellCP Porcine) with cryopreserved cellular porcine (CellCP Porcine), CellCP Porcine with cellular porcine (Cell Porcine), 12 month explanted cryopreserved decellularised porcine (ExpDCP Porcine) with DecellCP Porcine. 12 month DecellCP Porcine was also compared with cellular ovine PHVC (Cell Ovine). Wall and leaflet specimens from all the valve groups were subjected to uniaxial tensile testing to failure at 10 mm/min under hydrated conditions at 37°C. The biomechanical parameters (elastin phase modulus [Ee], collagen phase modulus [Ec], ultimate tensile stress [UTS]) were determined.
RESULTS: The biomechanical wall and leaflet parameters for CellCP Porcine were similar to Cell Porcine PHVC. No significant differences were found between DecellCP Porcine and CellCP Porcine for the leaflet parameters Ee, Ec and UTS. The Ee for DecellCP Porcine wall specimens was significantly increased compared to the CellCP Porcine specimens. No significant differences were found between ExpDCP Porcine and DecellCP Porcine for the wall parameters. The Ee for the ExpDCP Porcine radial leaflet specimens was significantly higher than DecellCP Porcine specimens. In the circumferential direction the UTS for ExpDCP Porcine leaflet specimens was significantly lower compared to DecellCP Porcine specimens. The comparison between ExpDCP Porcine and Cell Ovine showed several differences in the wall and leaflet biomechanical properties.
CONCLUSIONS: Cryopreservation did not affect the biomechanical properties of porcine PHVC, and the biomechanical properties of leaflets and wall (with exception of Ee) were preserved after decellularisation. Comparison between ExpDCP Porcine and DecellCP porcine demonstrated that the biomechanical properties of wall were preserved following implantation in sheep, however, several directional biomechanical properties of leaflets were altered. The differences in biomechanical properties between ExpDCP Porcine and Cell Ovine were expected, due to differences in valve species and size. Overall, this study provides valuable pre-clinical biomechanical data that can support clinical trial design.
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