title: Gamma radiation alters the ultrastructure in tissue-engineered heart valve scaffolds.
abstract: OBJECTIVE
  Xenogenic extracellular heart valve matrices have been suggested as scaffolds for tissue engineering. However, these matrices are immunogenic and stimulate an intense cell-mediated immune response and calcification. Mitigating the immunogenicity was attempted by different doses of gamma irradiation.
  
  
  METHODS
  Mechanical properties of gamma-irradiated porcine matrices and control matrices (nonirradiated) were examined by tensile strength testing. Irradiated matrices (1, 10, 50, and 100 gray [Gy]) and control matrices were implanted subcutaneously in Wistar rats (n = 20). After 24 h, 1, 2, 3, and 4 weeks the explants were examined by light microscopy and transmission electron microscopy. Calcium (Ca) content was determined using inductively coupled plasma-mass spectrometry. Antibody reaction against porcine tissue in the rat serum was determined.
  
  
  RESULTS
  Tensile strength increased in irradiated matrices at the expense of elasticity. Ten gray-irradiated leaflets showed minimal lymphocytic inflammatory infiltration with preservation of ultrastructure. Ca levels after 2 weeks were as follows: control (0 Gy), 388 +/- 264 microg/mg; 1 Gy, 240 +/- 95 microg/mg; 10 Gy, 188 +/- 54 microg/mg; 50 Gy, 289 +/- 94 microg/mg; 100 Gy, 651 +/- 57 microg/mg. All implants still elicit an antibody immunoglobulin G reaction.
  
  
  CONCLUSIONS
  Exposure to 10 Gy gamma irradiation reduces lymphocytic inflammatory infiltrates and Ca levels in acellular porcine matrices with preservation of structural integrity. This could prolong the durability of these matrices.
authors.affiliation: Heart Center, University Hospital Ghent, Ghent, Belgium.
authors.forename: Pamela
authors.initials: P
authors.lastname: Somers
authors.forename: Claude A
authors.initials: CA
authors.lastname: Cuvelier
authors.forename: Filip De
authors.initials: FD
authors.lastname: Somer
authors.forename: Maria
authors.initials: M
authors.lastname: Cornelissen
authors.forename: Eric
authors.initials: E
authors.lastname: Cox
authors.forename: Marc
authors.initials: M
authors.lastname: Verloo
authors.forename: Koen
authors.initials: K
authors.lastname: Chiers
authors.forename: Guido
authors.initials: G
authors.lastname: van Nooten
mesh_terms: D000818:Animals; D001705:Bioprosthesis; D004307:Dose-Response Relationship, Radiation; D055119:Elastic Modulus / Q000528:radiation effects; D019544:Equipment Failure Analysis; D005720:Gamma Rays; D006350:Heart Valve Prosthesis; D006351:Heart Valves / Q000502:physiology* / Q000528:radiation effects* / Q000648:ultrastructure; D011474:Prosthesis Design; D011829:Radiation Dosage; D051381:Rats; D017208:Rats, Wistar; D013718:Tensile Strength / Q000528:radiation effects; D023822:Tissue Engineering / Q000379:methods*