Vitro Models of the Tracheo-Bronchial Epithelium

Keywords Bronchial epithelium Pulmonary drug absorption Pulmonary metabolism Drug transport Permeability 

CFTR Cystic fibrosis transmembrane conductance regulator 

NHBE Normal human bronchial epithelial cells 

The tracheo-bronchial epithelium forms the interface between the conducting airways and inspired air. As described above, the epithelium is layered upon a connective tissue substratum consisting of a basement membrane, lamina propria, and submucosa [6], The submucosa contains elastic fibres, a muscularis mucosa, connective tissues and seromucous glands. Lymphatics are also located in the bronchial walls [2], 

While all the aforementioned cell types form the epithelial surface of the airways, basal cells reside deep in the tracheo-bronchial epithelium and are not directly in contact with the airway lumen. Basal cells are considered as the stem cell or progenitor cell of the bronchial epithelium and are pyramidal in shape with a low cytoplasmic/nuclear volume ratio [8, 15-17], 

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Chapter 10 In Vitro Models of the Tracheo-Bronchial Epithelium... 

A variety of cell culture systems for the modelling of the tracheo-bronchial epithelium are available. These include primary cultures and cell lines of human and animal origins, plus airway cells with characteristics of lung disease such as CF. The advantages and limitations of using a simple culture system compared to one that recreates to a greater extent the epithelial structure and function in vitro should be considered according to the pre-clinical application required. However, this choice is complicated by the lack of comparative data, both between the different cell systems and for in vitro-in vivo correlation, upon which to base such decisions. 

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