title: Tissue-engineered mitral valve: morphology and biomechanics †.
abstract: OBJECTIVE
  The present study aimed at developing tissue-engineered mitral valves based on cell-free ovine mitral allografts.
  
  
  METHODS
  The ovine mitral valves (OMVs) (n = 46) were harvested in the local slaughter house. They were decellularized using detergent solutions and DNase. The effectiveness of decellularization was assessed by histological (haematoxylin-eosin, Movat's pentachrome) and immunofluorescent staining (for DNA and α-Gal), and DNA-quantification. To reveal the receptiveness of decellularized tissue to endothelial cells (ECs), the valve leaflets were reseeded with ovine ECs, derived from endothelial progenitor cells in vitro. For assessment of biomechanical properties, uniaxial tensile tests were carried out.
  
  
  RESULTS
  Histology and immunofluorescent staining revealed absence of cell nuclei in decellularized leaflets, chordae and papillary muscles. According to the software for immunofluorescence analysis, reduction in DNA and α-Gal was 99.9 and 99.6%, respectively. DNA-quantification showed 71.2% reduction in DNA content without DNase and 96.4% reduction after DNase treatment. Decellularized leaflets were comparable with native in ultimate tensile strain (native, 0.34 ± 0.09 mm/mm, vs decellularized, 0.44 ± 0.1 mm/mm; P = 0.09), and elastin modulus (native, 0.39 ± 0.27, vs decellularized, 0.57 ± 0.55, P = 0.46), had increased ultimate tensile stress (native, 1.23 ± 0.35 MPa, vs decellularized 2.12 ± 0.43 MPa; P = 0.001) and collagen modulus (native, 5.5 ± 1.26, vs decellularized, 8.29 ± 2.9; P = 0.04). After EC seeding, immunofluorescent staining revealed a monolayer of CD31-, eNOS- and vWF-positive cells on the surface of the leaflet, as well as a typical cobble-stone morphology of those cells.
  
  
  CONCLUSIONS
  Decellularization of ovine mitral valve results in a mitral valves scaffold with mechanical properties comparable with native tissue, and a graft surface, which can be repopulated by endothelial cells.
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany yablonski.pavel@mh-hannover.de pavel.yablonski@gmail.com.
authors.forename: Pavel
authors.initials: P
authors.lastname: Iablonskii
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Serghei
authors.initials: S
authors.lastname: Cebotari
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Igor
authors.initials: I
authors.lastname: Tudorache
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Marisa
authors.initials: M
authors.lastname: Granados
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Lucrezia
authors.initials: L
authors.lastname: Morticelli
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Goecke
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Norman
authors.initials: N
authors.lastname: Klein
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Sotirios
authors.initials: S
authors.lastname: Korossis
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Andres
authors.initials: A
authors.lastname: Hilfiker
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG) Hannover Medical School, Hannover, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Haverich
mesh_terms: D064591:Allografts; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001696:Biomechanical Phenomena; D001705:Bioprosthesis; D049109:Cell Proliferation; D002478:Cells, Cultured; D004261:DNA Replication; D055119:Elastic Modulus; D066026:Endothelial Progenitor Cells / Q000378:metabolism / Q000502:physiology*; D006350:Heart Valve Prosthesis; D008422:Materials Testing; D008943:Mitral Valve / Q000166:cytology / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011474:Prosthesis Design; D012756:Sheep; D013718:Tensile Strength; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D015415:Biomarkers; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D014841:von Willebrand Factor; D052250:Nitric Oxide Synthase Type III
keywords: Mitral homograft; Mitral valve; Tissue engineering