title: Decellularization reduces the immune response to aortic valve allografts in the rat.
abstract: OBJECTIVE
  Cryopreserved valve allografts used in congenital cardiac surgery are associated with a significant cellular and humoral immune response. This might be reduced by removal of antigenic cellular elements (decellularization). The aim of this study was to determine the immunologic effect of decellularization in a rat allograft valve model.
  
  
  METHODS
  Brown Norway and Lewis rat aortic valves were decellularized with a series of hypotonic and hypertonic buffers, protease inhibitors, gentle detergents (Triton X-100), and phosphate-buffered saline. Valves were implanted into Lewis rats in syngeneic and allogeneic combinations. Cellular (CD3 and CD8) infiltrates were assessed with morphometric analysis, and the humoral response was assessed with flow cytometry.
  
  
  RESULTS
  Morphometric analysis identified a significant reduction in CD3 + cell infiltrates (cells per square millimeter of leaflet tissue) in decellularized allografts compared with that seen in nondecellularized allografts at 1 (79 +/- 29 vs 3310 +/- 223, P < .001), 2 (26 +/- 11 vs 109 +/- 20, P = .004), and 4 weeks (283 +/- 122 vs 984 +/- 145, P < .001). Anti-CD8 staining confirmed the majority of infiltrates were cytotoxic T cells. Flow cytometric mean channel fluorescence intensity identified a negative shift (abrogated antibody formation) for decellularized allografts compared with nondecellularized allografts at 2 (19 +/- 1 vs 27 +/- 3, P = .033), 4 (35 +/- 2 vs 133 +/- 29, P = .001), and 16 weeks (28 +/- 2 vs 166 +/- 54, P = .017).
  
  
  CONCLUSIONS
  Decellularization significantly reduces the cellular and humoral immune response to allograft tissue. This could prolong the durability of valve allografts and might prevent immunologic sensitization of allograft recipients.
authors.affiliation: Department of Surgery, University of Alberta, Edmonston, Canada. srmeyer@ualberta.ca
authors.forename: Steven R
authors.initials: SR
authors.lastname: Meyer
authors.forename: Jeevan
authors.initials: J
authors.lastname: Nagendran
authors.forename: Leena S
authors.initials: LS
authors.lastname: Desai
authors.forename: Gina R
authors.initials: GR
authors.lastname: Rayat
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Churchill
authors.forename: Colin C
authors.initials: CC
authors.lastname: Anderson
authors.forename: Ray V
authors.initials: RV
authors.lastname: Rajotte
authors.forename: Jonathan R T
authors.initials: JR
authors.lastname: Lakey
authors.forename: David B
authors.initials: DB
authors.lastname: Ross
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000276:immunology; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D007111:Immunity, Cellular / Q000276:immunology*; D007158:Immunologic Techniques; D008297:Male; D023421:Models, Animal; D051381:Rats; D013048:Specimen Handling / Q000379:methods*; D013601:T-Lymphocytes / Q000276:immunology; D014181:Transplantation Immunology / Q000276:immunology*