Abstract

Airway and breathing are the two most immediate functions of mammalian life. The respiratory tract represents the interface between the body and the atmosphere around us, and thus represents a first line of defense against inhaled challenges such as potential allergens, pollutants and cigarette smoke. Sequentially, it is responsible for filtering, humidifying air (nose),speech and protecting the respiratory tract from inhalation of ingested materials and saliva (larynx), conducting air and mucus (tracheobronchial tree), and gas exchange (alveoli). Disorders affecting these functions can have devastating effects on quality and duration of life, and our ability to manage some of the most serious of these with conventional treatments is severely limited.

Regenerative medicine has considerable potential to bridge this gap between what present therapy can achieve and the restoration of normal existence. The most striking example of this was the restoration of normal function (and life) to a 31-year-old mother whose tracheobroinchial tree had been ravaged by tuberculosis. In 2008, a stem-cell based, tissue-engineered airway implant was prepared and transplanted with immediate normalisation of lung function. We built on this experience by replacing the whole trachea of an 11 year old boy in 2010. However, there is a long way to go before this success may be translated into a raft of treatments for persons with severe disease at all levels of the respiratory tract. We review progress at each of these levels.