title: Tissue engineering of autologous human heart valves using cryopreserved vascular umbilical cord cells.
abstract: BACKGROUND
  Tissue engineering of autologous heart valves with the potential to grow and to remodel represents a promising concept in pediatric cardiovascular surgery. Currently we are exploring the impact of cryopreserved human umbilical cord cells (CHUCCs) for the fabrication of tissue-engineered heart valves for patients diagnosed prenatally with congenital heart lesions, potentially enabling heart valve replacement in the early years of life.
  
  
  METHODS
  Human umbilical cord cells were isolated from vascular segments of umbilical cords and cryopreserved in a cell bank. After 12 weeks the cryopreserved cells were again expanded in culture and characterized by histology, immunohistochemistry, and proliferation assays. Trileaflet heart valve scaffolds were fabricated from a porous polymer (P4HB, Tepha Inc, Cambridge, MA) and sequentially seeded with CHUCCs (n = 10). Five of the heart valve constructs were grown for 7 days in a pulse duplicator and, as a control, five constructs were grown under static cell culture conditions for 7 days. Analysis of all tissue-engineered heart valves included histology, immunohistochemistry, electron microscopy, functional analysis, and biomechanical and biochemical examination.
  
  
  RESULTS
  We found that CHUCCs remained viable after 12 weeks of cryopreservation and showed a myofibroblast-like morphology that stained positive for alpha-actin and fibroblast specific marker. Histology of the tissue-engineered heart valves showed layered tissue formation, including connective tissue between the inside and the outside of the porous scaffold. Immunohistochemistry was positive for collagen (types I, III, and IV), desmin, laminin, and alpha-actin. Electron microscopy showed that the cells had grown into the pores and formed a confluent tissue layer during maturation in the pulsatile flow system. Biochemical examination showed an increase of extracellular matrix formation in constructs after pulsatile flow exposure compared with the static control group. Functional analysis demonstrated a physiological increase of the intracellular Ca2+ concentration of the recultivated cells and the conditioned constructs after stimulation with histamine.
  
  
  CONCLUSIONS
  This study demonstrates in vitro generation of viable and functional human heart valves based on CHUCCs and biomimetic flow culture systems. The CHUCCs demonstrated excellent growth potential and abilities of in vitro tissue formation. These findings suggest the potential benefit of establishing autologous human cell banks for pediatric patients diagnosed intrauterinely with congenital defects that will potentially require heart valve replacement in the early years of life.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum Berlin, Germany. ralf.sodian@med.uni-muenchen.de
authors.forename: Ralf
authors.initials: R
authors.lastname: Sodian
authors.forename: Cora
authors.initials: C
authors.lastname: Lueders
authors.forename: Liv
authors.initials: L
authors.lastname: Kraemer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kuebler
authors.forename: Mehdi
authors.initials: M
authors.lastname: Shakibaei
authors.forename: Bruno
authors.initials: B
authors.lastname: Reichart
authors.forename: Sabine
authors.initials: S
authors.lastname: Daebritz
authors.forename: Roland
authors.initials: R
authors.lastname: Hetzer
mesh_terms: D000199:Actins / Q000032:analysis; D001696:Biomechanical Phenomena; D001705:Bioprosthesis; D019149:Bioreactors; D002118:Calcium / Q000378:metabolism; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods*; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000637:transplantation; D003094:Collagen / Q000032:analysis; D000013:Congenital Abnormalities / Q000175:diagnosis / Q000196:embryology; D003239:Connective Tissue Cells / Q000166:cytology; D015925:Cryopreservation; D003893:Desmin / Q000032:analysis; D005109:Extracellular Matrix / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology* / Q000637:transplantation; D006350:Heart Valve Prosthesis; D006351:Heart Valves / Q000002:abnormalities*; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D007231:Infant, Newborn; D007797:Laminin / Q000032:analysis; D008854:Microscopy, Electron; D032446:Myoblasts / Q000166:cytology* / Q000637:transplantation; D011296:Prenatal Diagnosis; D011673:Pulsatile Flow; D013718:Tensile Strength; D023822:Tissue Engineering / Q000295:instrumentation / Q000379:methods*; D014182:Transplantation, Autologous; D014469:Umbilical Arteries / Q000166:cytology*; D014470:Umbilical Cord / Q000098:blood supply / Q000166:cytology
chemical_list: D000199:Actins; D003893:Desmin; D007797:Laminin; D006632:Histamine; D003094:Collagen; D002118:Calcium