A TISSUE ENGINEERED SELF-ASSEMBLING CONTRACTILE AIRWAY SMOOTH MUSCLE MODEL

Abstract

The hollow structure of the small airways is central to their function but can be challenging to represent in cell culture for the study of airway diseases such as asthma. Airway smooth muscle (ASM) cell-based tissues in the shape of rings present a unique opportunity to preserve this geometry in vitro and provide a model that can be utilized to explore altered ASM mechanical behaviour in response to environmental and biochemical cues. A system for the fabrication of toroidal ASM cell tissues in a custom PDMS plate format was designed and optimized. Characterization of the gene and protein expression response of the tissue rings found stable expression of ECM and contraction-associated transcripts, while measures of tissue mechanics such as stiffness increased as the tissue rings developed. Altered tissue mechanics and increased expression of type I collagen, fibronectin, smMHC, and α-SMA transcripts, as well as fibronectin protein levels, could be detected in response to the signaling factor TGF-β1. Contraction of the tissue rings was assayed, and the baseline contraction of the rings was found to be primarily governed by ROCK and not by smooth muscle activation. Separately, activation of the ASM with histamine or methacholine could enhance contractility, as could treatment with TGF-β1, LPA, PDGF, and TNF-α. The self-assembly of cells into ring-shaped tissues provides a versatile platform for the study of ASM cells in both health and disease.