title: Construction of an autologous tissue-engineered venous conduit from bone marrow-derived vascular cells: optimization of cell harvest and seeding techniques.
abstract: BACKGROUND
  Currently available vascular grafts for pediatric cardiovascular operations are limited by their inability to grow. Tissue-engineering techniques can be used to create vascular grafts with the potential for repair, remodeling, and growth. This study demonstrates the feasibility of constructing an autologous tissue-engineered venous conduit from bone marrow-derived vascular cells (BMVCs) in the ovine animal model.
  
  
  METHODS
  Ovine mononuclear cells were isolated from the bone marrow, cultured in endothelial growth medium, and characterized with immunocytochemistry. Biodegradable tubular scaffolds were constructed from polyglycolic acid mesh coated with a copolymer of poly[epsilon-caprolactone-L-lactide]. Scaffolds were seeded at various cell concentrations and incubation times to optimize seeding conditions for the construction of an autologous venous conduit. Using optimized conditions, 6 tissue-engineered vascular grafts were implanted as inferior vena cava interposition grafts in juvenile lambs. Grafts were assessed for patency at days 1 to 30 postoperatively and explanted for histological and immunohistochemical analysis.
  
  
  RESULTS
  A mixed cell population of BMVCs consisting of smooth muscle cells and endothelial cells was cultured from ovine sternal bone marrow. A seeding concentration of 2 x 10(6) cells/cm2 and 7 days of postseeding incubation were optimal for creating a confluent cellular layer on the polyglycolic acid/poly[epsilon-caprolactone-L-lactide]) scaffold. Grafts were explanted up to 4 weeks postoperatively. All grafts were patent without evidence of thrombosis. Histological evaluation of the explanted grafts demonstrated neo-endothelialization. Graft wall was composed of neo-tissue made up of residual polymer matrix, mesenchymal cells, and extracellular matrix without evidence of calcification.
  
  
  CONCLUSIONS
  Bone marrow-derived vascular cells, containing endothelial and smooth muscle cells, can be isolated and cultured from ovine sternal bone marrow and used as a cell source for vascular tissue engineering. Our optimized techniques for BMVC harvest and seeding onto biodegradable scaffolds can be used for studying autologous tissue-engineered vascular grafts in the ovine animal model.
authors.affiliation: Department of Surgery, Yale University School of Medicine, New Haven, CT 06510, USA.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Roh
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Brennan
authors.forename: Reynold I
authors.initials: RI
authors.lastname: Lopez-Soler
authors.forename: Peter M
authors.initials: PM
authors.lastname: Fong
authors.forename: Amit
authors.initials: A
authors.lastname: Goyal
authors.forename: Alan
authors.initials: A
authors.lastname: Dardik
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Breuer
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001705:Bioprosthesis; D001807:Blood Vessel Prosthesis; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D042783:Endothelial Cells; D005240:Feasibility Studies; D032389:Myocytes, Smooth Muscle; D011091:Polyesters; D011100:Polyglycolic Acid; D012756:Sheep; D013526:Surgical Mesh; D023822:Tissue Engineering
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; D011100:Polyglycolic Acid; C062968:lactide-caprolactone copolymer