Abstract
After more than 50 years of research, airway transplantation remains a major challenge in the fields of thoracic surgery and regenerative medicine. Five principal types of tracheobronchial substitutes, including synthetic prostheses, bioprostheses, allografts, autografts and bioengineered conduits have been evaluated experimentally in numerous studies. However, none of these works have provided a standardized technique for the replacement of the airways. More recently, few clinical attempts have offered encouraging results with ex vivo or stem cell–based engineered airways and tracheal allografts implanted after heterotopic revascularization. In 1997, we proposed a novel approach: the use of aortic grafts as a biological matrix for extensive airway reconstruction. In vivo regeneration of epithelium and cartilage were demonstrated in animal models. This led to the first human applications using cryopreserved aortic allografts that present key advantages because they are available in tissue banks and do not require immunosuppressive therapy. Favorable results obtained in pioneering cases have to be confirmed in larger series of patients with extensive tracheobronchial diseases.
Highlights
After more than 50 years of research, airway transplantation remains a major challenge in the fields of thoracic surgery and regenerative medicine
Review Inhibition to tracheal surgery before 1960 was explained by difficulties related to perioperative ventilation, the poor healing capacity of cartilage and, the “2-cm Belsey rule” stipulating that it was not possible to remove more than 2 cm of the trachea with primary reconstruction [1]
Airway transplantation: the five main methods of research In 2004, the various tracheal substitutes and techniques of reconstruction were classified by Grillo into five categories: foreign materials, nonviable tissues, tracheal allotransplantation, autogenous tissues and tissue engineering [6]
Summary
It is still unclear whether we are closer to the Holy Grail of airway transplantation with the use of cryopreserved aortic allografts. What we know is that this structure could have key advantages because it is a biologic structure available at tissue banks. This ideal matrix promoted in vivo in situ tissue engineering in animal models. The current difficulties are related to the delayed cartilage regeneration and the need for a permanent stent in human. This requires new studies to establish a standardized solution to the far unsolved problem of airway transplantation. Authors’ contributions All authors drafted the manuscript. All authors read and approved the final manuscript
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