The SULEEI Procedure - A Novel Approach For Crosslinking And Sterilization Of Pericardia For Manufacturing Bioprosthetic Heart Valves
Simona Walker1, Jessy Schönfelder1, Aline Jakob2, Christiane Wetzel1, Sems-Malte Tugtekin2, Michael C Hacker3, Michaela Schulz-Siegmund3.
1Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, Dresden, Germany, 2Department of Cardiac Surgery, Faculty of Medicine CGC, Technische Universität Dresden, Herzzentrum Dresden, Dresden, Germany, 3Institute of Pharmacy, Pharmaceutical Technology, Leipzig University, Leipzig, Germany.
OBJECTIVE: Long term results of current bioprosthetic heart valves are still limited due to valve degeneration which often result in re-interventions. In order to prevent degenerative processes, established surface preservation methods of tissue materials used for valve reconstruction are being reconsidered. Common approaches, which include the application of glutaraldehyde, are associated with calcification and cytotoxicity. Both of which initiate an ongoing degenerative process leading to prosthesis dysfunction. The novel SULEEI procedure for sterilization and preservation via photo-initiated UVA treatment and low-energy electron irradiation (LEEI) was developed and the sterility, mechanical properties and cytocompatibility assessed.
METHODS: Decellularized pericardial scaffolds were treated with riboflavin/UVA irradiation and LEEI with a dose of 31 kGy. Sterility was determined by turbidity assessment according to DIN EN ISO 11137. Biomechanical properties were analysed by uniaxial tensile test. Cytocompatibility was assessed by seeding human umbilical vein endothelial cells (HUVEC) on treated pericardia and quantification of their metabolic activity and cell number.
RESULTS: A bioburden of 5.1*105 ± 4.6*105 viable bacteria per cm2 was determined on non-irradiated pericardia. After LEEI, no viable pathogens could be detected in any of the samples indicating a successful sterilization. Ultimate tensile strength and elastic modulus after SULEEI-treatment were not significantly altered compared to glutaraldehyde-treatment. However, the stress at 10 % strain of SULEEI-treated pericardia was significantly increased compared to glutaraldehyde-treated pericardia. The overall metabolic activity and the number of HUVEC cells seeded on SULEEI-treated pericardia was significantly increased compared to glutaraldehyde-treated pericardia. No difference between decellularized and SULEEI-treated pericardia could be observed.
CONCLUSIONS: The SULEEI procedure may be a promising new methodology for processing of pericardia for use in heart valve prosthesis. Further analysis, including the long-term mechanics are required in order to further assess the suitability as a material for bioprosthetic heart valves.
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