Avancées en chirurgie trachéale : a-t-on enfin trouvé le substitut idéal à la trachée ?

Tracheal replacement with aortic grafts: Bench to clinical practice

Tracheal reconstruction following extensive resection for malignant or benign lesions remains a major challenge in thoracic surgery. Numerous studies have attempted to identify the optimal tracheal replacement with different biological or prosthetic materials, such as various homologous and autologous tissues, with no encouraging outcomes. Recently, a few clinical studies reported attaining favorable outcomes using in vitro or stem cell-based airway engineering and also with tracheal allograft implantation following heterotopic revascularization. However, none of the relevant studies offered a standardized technology for airway replacement. In 1997, a novel approach to airway reconstruction was proposed, which involved using aortic grafts as the biological matrix. Studies on animal models reported achieving in-vivo cartilage and epithelial regeneration using this approach. These encouraging results inspired the subsequent application of cryopreserved aortic allografts in humans for the first time. Cryopreserved aortic allografts offered further advantages, such as easy availability in tissue banks and no requirement for immunosuppressive treatments. Currently, stented aortic matrix-based airway replacement has emerged as a standard approach, and its effectiveness was also verified in the recently reported TRITON-01 study. In this context, the present review aims to summarize the current status of the application of aortic grafts in tracheal replacement, including the latest advancements in experimental and clinical practice.

Airway transplantation: a challenge for regenerative medicine

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.

Tracheobronchial bio-engineering: biotechnology fulfilling unmet medical needs

The development of substitutes for the human trachea or its bronchial tree represents a niche application in the rapidly advancing scientific field of Regenerative Medicine. Despite a comparatively small research foundation in the field of tracheo-bronchial bioengineering, four different approaches have already been translated into clinical settings and applied in patients. This can be attributed to the lack of established treatment options for a small group of patients with extensive major airway disease. In this review, the clinical background and tissue-specific basics of tracheo-bronchial bioengineering will be evaluated. Focusing on the clinical applications of bioengineered tracheal tissues, a "top-down" or "bedside-to-bench" analysis is performed in order to guide future basic and clinical research activities for airway bioengineering.