title: Airway tissue engineering: an update.
abstract: BACKGROUND
  Prosthetic materials, autologous tissues, cryopreserved homografts and allogeneic tissues have thus far proven unsuccessful in providing long-term functional solutions to extensive upper airway disease and damage. Research is therefore focusing on the rapidly expanding fields of regenerative medicine and tissue engineering in order to provide stem cell-based constructs for airway reconstruction, substitution and/or regeneration.
  
  
  METHODS
  Advances in stem cell technology, biomaterials and growth factor interactions have been instrumental in guiding optimization of tissue-engineered airways, leading to several first-in-man studies investigating stem cell-based tissue-engineered tracheal transplants in patients. Here, we summarize current progress, outstanding research questions, as well as future directions within the field.
  
  
  CONCLUSIONS
  The complex immune interaction between the transplant and host in vivo is only beginning to be untangled. Recent progress in our understanding of stem cell biology, decellularization techniques, biomaterials and transplantation immunobiology offers the prospect of transplanting airways without the need for lifelong immunosuppression. In addition, progress in airway revascularization, reinnervation and ever-increasingly sophisticated bioreactor design is opening up new avenues for the construction of a tissue-engineered larynx. Finally, 3D printing is a novel technique with the potential to render microscopic control over how cells are incorporated and grown onto the tissue-engineered airway.
authors.affiliation: UCL Institute of Child Health, Department of Surgery , 30 Guilford Street, London WC1N 1EH , UK +44 07989 331573 ; j.fishman@ucl.ac.uk.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Fishman
authors.forename: Katherine
authors.initials: K
authors.lastname: Wiles
authors.forename: Mark W
authors.initials: MW
authors.lastname: Lowdell
authors.forename: Paolo
authors.initials: P
authors.lastname: De Coppi
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Elliott
authors.forename: Anthony
authors.initials: A
authors.lastname: Atala
authors.forename: Martin A
authors.initials: MA
authors.lastname: Birchall
mesh_terms: D021522:Bioartificial Organs; D006801:Humans; D007818:Laryngeal Diseases / Q000601:surgery*; D007830:Larynx / Q000637:transplantation*; D044968:Regenerative Medicine / Q000379:methods; D033581:Stem Cell Transplantation / Q000379:methods; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds; D014132:Trachea / Q000637:transplantation*; D014133:Tracheal Diseases / Q000601:surgery*; D014184:Transplantation, Homologous
keywords: airway management; angiogenesis; artificial organs; biocompatible materials; bioreactors; larynx; regenerative medicine; stem cells; tissue engineering; tissue scaffolds; trachea; transplantation