Cyclic Stretching of Fibrotic Microtissue Array for Evaluation of Anti-Fibrosis Drugs

Progression of pulmonary fibrosis, characterized by the deterioration of lung tissue's mechanical properties, is affected by respiratory motion-induced dynamic loading. Since the development of anti-fibrosis drugs faces major hurdles in animal tests and human clinical trials, preclinical models that can recapitulate fibrosis progression under physiologically-relevant cyclic loading hold great promise. However, the integration of these two functions has not been achieved in existing models.

Recently we developed static human lung microtissue arrays that recapitulate the progressive changes in tissue mechanics during lung fibrogenesis. In the current study, we integrate the lung microtissue array with a membrane stretching system to enable dynamic loading to the microtissues. The effects of a pro-fibrotic agent and anti-fibrosis drugs were tested under cyclic stretching.

Cyclic stretching that mimics respiratory motion was shown to affect the cytoskeletal organization and cellular orientation in the microtissue and cause the increase in microtissue contractility and stiffness. Fibrosis induction using TGF-β1 further promoted fibrosis-related mechanical activity of the lung microtissues. Using this system, we examined the therapeutic effects of two FDA approved anti-fibrotic drugs. Our results showed that Nintedanib was able to fully inhibit TGF-β1 induced force increase but only partially inhibited stretching induced force increase. In contrast, Pirfenidone was able to fully inhibit both TGF-β1 induced force increase and stretching-induced force increase.

Together, these results highlight the pathophysiologically-relevant modeling capability of the current fibrotic microtissue system and demonstrated the potential of this system to be used for anti-fibrosis drug screening.