title: Effects of combined cryopreservation and decellularization on the biomechanical, structural and biochemical properties of porcine pulmonary heart valves.
abstract: Non-fixed, decellularized allogeneic heart valve scaffolds seem to be the best choice for heart valve replacement, their availability, however, is quite limited. Cryopreservation could prolong their shelf-life, allowing for their ideal match to a recipient. In this study, porcine pulmonary valves were decellularized using detergents, either prior or after cryopreservation, and analyzed. Mechanical integrity was analyzed by uniaxial tensile testing, histoarchitecture by histological staining, and composition by DNA, collagen (hydroxyproline) and GAG (chondroitin sulfate) quantification. Residual sodium dodecyl sulfate (SDS) in the scaffold was quantified by applying a methylene blue activation assay (MBAS). Cryopreserved decellularized scaffolds (DC) and scaffolds that were decellularized after cryopreservation (CD) were compared to fresh valves (F), cryopreserved native valves (C), and decellularized only scaffolds (D). The E-modulus and tensile strength of decellularized (D) tissue showed no significant difference compared to DC and CD. The decellularization resulted in an overall reduction of DNA and GAG, with DC containing the lowest amount of GAGs. The DNA content in the valvular wall of the CD group was higher than in the D and DC groups. CD valves showed slightly more residual SDS than DC valves, which might be harmful to recipient cells. In conclusion, cryopreservation after decellularization was shown to be preferable over cryopreservation before decellularization. However, in vivo testing would be necessary to determine whether these differences are significant in biocompatibility or immunogenicity of the scaffolds.
  
  
  
  Absence of adverse effects on biomechanical stability of acellular heart valve grafts by cryopreservation, neither before nor after decellularization, allows the identification of best matching patients in a less time pressure dictated process, and therefore to an optimized use of a very limited, but best-suited heart valve prosthesis.
authors.affiliation: Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany; Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
authors.forename: Karolina
authors.initials: K
authors.lastname: Theodoridis
authors.affiliation: Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany; Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Müller
authors.affiliation: Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany; Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Ramm
authors.affiliation: Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany; Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Findeisen
authors.affiliation: Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany; Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Andrée
authors.affiliation: Lower Saxony Centre for Biomedical Engineering Implant Research and Development, Hannover Medical School, Hannover, Germany; Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
authors.forename: Sotirios
authors.initials: S
authors.lastname: Korossis
authors.affiliation: Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany; Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Haverich
authors.affiliation: Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany; Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany. Electronic address: hilfiker.andres@mh-hannover.de.
authors.forename: Andres
authors.initials: A
authors.lastname: Hilfiker
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D016923:Cell Death; D015925:Cryopreservation / Q000379:methods*; D008422:Materials Testing; D011664:Pulmonary Valve / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D034421:Sus scrofa; D013718:Tensile Strength
keywords: Cryopreservation; Decellularization; Heart valve; Tissue engineering