Supercritical carbon dioxide decellularised pericardium: Mechanical and structural characterisation for applications in cardio-thoracic surgery.

Introduction: Many biomaterials are used in cardio-thoracic surgery with good short-term results. However, calcification, dehiscence, and formation of scar tissue are reported. The aim of this research is to characterise decellularised pericardium after supercritical carbon dioxide (scCO) processing as an alternative biological material for uses in cardio-thoracic surgery.

Methods: Porcine and bovine pericardium were decellularised using scCO. Mechanical properties such as tensile strength, elastic modulus, fracture toughness and suture retention strength were determined. Ultrastructure was visualised using Scanning Electron Microscopy. Water uptake and swelling was experimentally determined. Commercially available glutaraldehyde treated bovine pericardium was used as gold standard for comparison.

Results: scCO decellularised porcine (and bovine pericardium) maintained their tensile strength compared to untreated native pericardium (13.3 ± 2.4MPa vs 14.0 ± 4.1MPa, p = 0.73). Tensile strength of glutaraldehyde treated pericardium was significantly higher compared to untreated pericardium (19.4 ± 7.3MPa vs 10.2 ± 2.2MPa, p = 0.02). Suture retention strength of scCO treated pericardium was significantly higher than glutaraldehyde treated pericardium (p = 0.01). We found no anisotropy of scCO or glutaraldehyde treated pericardium based on a trouser tear test. Ultrastructure was uncompromised in scCO treated pericardium, while glutaraldehyde treated pericardium showed deterioration of extracellular matrix.

Conclusion: scCO processing preserves initial mechanical and structural properties of porcine and bovine pericardium, while glutaraldehyde processing damages the extracellular matrix of bovine pericardium. Decellularisation of tissue using scCO might give long-term solutions for cardio-thoracic surgery without compromising initial good mechanical properties.