title: Development of a next-generation tissue valve using a glutaraldehyde-fixed porcine aortic valve treated with decellularization, α-galactosidase, space filler, organic solvent and detoxification.
abstract: OBJECTIVE
  Conventional crosslinking with glutaraldehyde (GA) renders cardiac xenografts inert, non-biodegradable and non-antigenic, but is a main cause for dystrophic calcification due to phospholipids, free aldehyde groups and residual antigenicity. A significant immune reaction to the galactose-α-1,3 galactose β-1,4-N-acetylglucosamine (α-Gal) of a GA-fixed cardiac xenograft occurs, leading to calcification. We developed a next-generation α-Gal-free tissue valve with GA-fixed cardiac xenografts, treated using a novel combined anticalcification protocol including immunological modification, which was demonstrated effective in a small animal study.
  
  
  METHODS
  Porcine aortic valves were decellularized with 1% sodium dodecyl sulphate, 1% Triton X-100 and 1% sodium lauroyl sarcosinate and immunologically modified with α-galactosidase. The valves were treated by a polyethylene glycol space filler, fixed with GA in 75% ethanol + 5% octanol and detoxified with glycine. We manufactured the tissue valve with the porcine aortic valve mounted on a Nitinol (nickel-titanium memory alloy) plate. The tissue valve was placed under in vitro mock circulation, and durability from mechanical stress was evaluated for 100 days. Ten sheep underwent mitral valve replacement with the tissue valve, and haemodynamic, radiological, immunohistopathological and biochemical results were obtained for 18 months after implantation.
  
  
  RESULTS
  The in vitro circulation experiment demonstrated that the valve functioned well with good morphology. Eight sheep survived for 1, 2, 5, 10, 14, 53, 546 and 552 days after mitral valve replacement, but two sheep did not survive. An evaluation by echocardiography and cardiac catheterization demonstrated good haemodynamic status and function of the mitral valve at 18 months after implantation. The xenografts were well preserved without a α-Gal immune reaction or calcification based on the immunological, radiographic, microscopic and biochemical examinations.
  
  
  CONCLUSIONS
  We developed a next-generation α-Gal-free tissue valve with simultaneous use of multiple anticalcification therapies and novel tissue treatments such as decellularization, immunological modification with α-galactosidase, space filler, an organic solvent and detoxification. Future investigations should evaluate α-Gal-free substitutes such as our tissue valve, and a future clinical study is warranted based on these promising preclinical results.
authors.affiliation: Seoul National University Hospital Clinical Research Institute, Xenotransplantation Research Center, Seoul, Republic of Korea Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hong-Gook
authors.initials: HG
authors.lastname: Lim
authors.affiliation: Seoul National University Hospital Clinical Research Institute, Xenotransplantation Research Center, Seoul, Republic of Korea Department of Pediatrics, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Gi Beom
authors.initials: GB
authors.lastname: Kim
authors.affiliation: Seoul National University Hospital Clinical Research Institute, Xenotransplantation Research Center, Seoul, Republic of Korea.
authors.forename: Saeromi
authors.initials: S
authors.lastname: Jeong
authors.affiliation: Seoul National University Hospital Clinical Research Institute, Xenotransplantation Research Center, Seoul, Republic of Korea Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea kyj@plaza.snu.ac.kr.
authors.forename: Yong Jin
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D000818:Animals; D001705:Bioprosthesis; D002114:Calcinosis / Q000517:prevention & control; D006328:Cardiac Catheterization; D004452:Echocardiography; D005976:Glutaral / Q000627:therapeutic use; D006350:Heart Valve Prosthesis; D008943:Mitral Valve / Q000601:surgery; D011092:Polyethylene Glycols / Q000627:therapeutic use; D012756:Sheep / Q000601:surgery; D023822:Tissue Engineering / Q000379:methods; D000520:alpha-Glucosidases
chemical_list: D011092:Polyethylene Glycols; D000520:alpha-Glucosidases; D005976:Glutaral
keywords: Bioengineering; Biomaterials; Bioprosthesis; Calcification; Heart valve; Xenograft