@ISB_Glasgow
DAVID WINTER YOUNG INVESTIGATOR AWARDS Cardiovascular
SS-0063
SUPERCRITICAL CARBON DIOXIDE DECELLULARISATION OF PERICARDIUM: MECHANICAL AND STRUCTURAL CHARACTERISATION FOR APPLICATIONS IN CARDIOVASCULAR SURGERY
Frank R. Halfwerk 1 2,*Jeroen Rouwkema 1Jan Gossen 3Bart Koopman 1Jan Grandjean 1 2
1Biomechanical Engineering, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 2Thoraxcentrum Twente, Medisch Spectrum Twente Hospital, Enschede, 3European Medical Contract Manufacturing,
Nijmegen, Netherlands
Introduction and Objectives: Pericardium is used in cardiovascular surgery as a temporary graft for heart tissue recovery, reconstruction of heart valves and aortic wall, closure of pericardium and reconstruction of blood vessels (arterioplasty). However, calcification, dehiscence and formation of scar tissue occurs in the long term. These issues, in part, may be caused by decellularisation and cross-linking by glutaraldehyde, used to prevent a pro-inflammatory immune response. Current decellularisation methods are enzymatic, physical or chemical processes and result in disruption of architecture, reduction of mechanical properties and loss of surface composition. Importantly, residual chemicals inhibit beneficial properties of a cell-free scaffold.
Moreover, these treatments induce a chronic inflammation, which result in calcification and limit lifespan of the graft to 10 years. This calcification is related to host metabolism, implant structure and mechanical factors. Reoperation is often required, with high mortality, morbidities and costs.
A new method of decellularisation is supercritical carbon dioxide (scCO2) processing; a mild but effective technique to
remove cells and fat from tissues. This technique uses non-toxic chemicals and does not require cross-linking that interfere with degradation and a constructive remodelling process.
Thus, the aim of this study is characterisation of mechanical and structural properties of scCO2 decellularised pericardium for applications in cardiovascular surgery.
Methods: Bovine and porcine pericardia were decellularised by scCO2 and compared with Peri-Guard® (bovine
pericardium cross-linked by glutaraldehyde). Ultimate tensile strength (UTS), elastic modulus and suture retention strength were determined using an uniaxial tensile tester in dry and hydrated samples. Suture retention strength was measured by Prolene 4-0 interrupted sutures. Ultrastructure was visualised using Scanning Electron Microscopy. Results: UTS of scCO2 decellularised porcine and bovine pericardium was comparable to untreated pericardium, while
UTS of Peri-Guard® was non-significantly higher (see Table 1). Elastic modulus was relatively high in Peri-Guard® and dry
scCO2 decellularised bovine pericardium, but was reduced by half in hydrated condition.
Suture retention strength was higher in dry and hydrated bovine pericardium, compared to Peri-Guard®. Three phenomena were observed: tearing, string cutting and slipping of surgical knot. Preservation of ultrastructure in scCO2
decellularised porcine pericardia (Figure 1) and some deterioration of ultrastructure was observed in Peri-Guard®.
Figure:
www.isbglasgow.com Caption: Ultrastructure of both rough and fibrous porcine pericardium decellularised by scCO2, visualised by Scanning Electron Microscopy. Inlay shows anatomic structures of pericardium. Magnification 50x.
Conclusion: Pericardium decellularised by scCO2 has superior mechanical properties with preservation of ultrastructure
and higher suture retention strength compared to Peri-Guard®. This makes scCO2 decellularisation a promising technique
and further mechanical characterisation, recellularisation capabilities and in vitro calcification should be investigated before use in cardiovascular surgery.
Table:
Source Treatment Tensile Strength (MPa) Elastic Modulus (MPa) Reference
Porcine Untreated 14.4 76 ± 10 Dong, 2013 Porcine X-100 8.0 51 ± 7 Dong, 2013 Porcine SDS
+Glutaraldehyde
7.3 ± 1.6 - Min, 2012 Porcine scCO2 (dry) 14.0 ±
4.1 131 ± 21 This study Human Untreated 7.6 ± 0.96 50 ± 3 Cohn, 1987 Human Glutaraldehyde 10 ± 3 51 ± 15 Yamashita,
2012 Bovine Untreated 8.9 ± 0.75 53 ± 4 Cohn, 1987 Bovine Glutaraldehyde (Peri-Guard) 19.4 ± 7.3 91 ± 38 This study Bovine Untreated 9 ± 3 26 ± 5 Hülsmann,
2012
@ISB_Glasgow Bovine SDS
+Glutaraldehyde
4.2 ± 1 5 ± 2 Hülsmann, 2012 Bovine scCO2 (dry) 11.0 ± 2 83 ± 14 This study
Bovine scCO2 (hydrated) 13.4 ± 3 48 ± 12 This study
Caption: Table 1 Mechanical properties of pericardia References: [1] Dong et al., J Surg Res, 183: 56-67, 2013.
[2] Min et al., Korean J Thor Cardiovasc Surg, 45: 368-379, 2012. [3] Cohn et al., Clin Mater, 2: 115-124, 1987.
[4] Yamashita et al., Ann Thorac Cardiovasc Surg, 18: 434-437, 2012. [5] Hülsmann et al., Xenotransplantation, 19: 286-297, 2012.
Disclosure of Interest: F. Halfwerk Conflict with: Supercritical carbon dioxide decellularised pericardium was provided free of charge by EMCM in a collaborative project between the University of Twente, Medisch Spectrum Twente Hospital and EMCM with an indirect financial relationship between FH and EMCM (partial honorarium). , J. Rouwkema: None Declared, J. Gossen: None Declared, B. Koopman: None Declared, J. Grandjean: None Declared
Keywords: None
