A bronchiole-on-a-chip and a stretching system for studying human disease model of asthma attack

Asthma is an important public health issue in developed and developing countries, with a prevalence of 300 million worldwide. It is a heterogeneous disease characterized by chronic airway inflammation and hyperresponsiveness. A bronchiole-on-a-chip with a compact stretching system, which is comparable to the small-size incubator and can provide continuous cyclical scratches, is reported here for emulating the physiology of asthma and other types of lung diseases with various breathing rates. In this study, bronchial smooth muscle cells (BSMCs) are cultured on the bronchiole-on-a-chip under cyclic stretching, mimicking the respiratory rates for healthy adults and asthma patients under bronchospasm. With the cyclical cell stretching, the physiology of BSMCs is affected. In an asthma-conditioned bronchial chip, secretions of pro-inflammatory cytokines IL-6 and IL-8 increase significantly from BSMCs compared with the static or healthy condition. In on-chip treatment studies, BSMCs are treated with various concentrations of indacaterol, a long-acting bronchodilator for asthma. The secretion of IL-6 is suppressed for the indacaterol-treated group under asthma conditions. The alignment of stretched BSMCs is also affected by mechanical stretching. Bronchiole-on-a-chip demonstrates the possibility of mimicking the physiological condition of asthma in vitro and a potential drug screening system for lung diseases.