1. ¹Division of Pulmonary and Critical Care Medicine, Northwestern University Medical School, Chicago, IL, USA
2. ²Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA

Correspondence: Dr DA Dean, Division of Pulmonary and Critical Care Medicine Feinberg School of Medicine, Northwestern University, 240 E. Huron Avenue, McGaw 2336 Chicago, IL 60611, USA. E-mail: dean@northwestern.edu

Received 24 March 2005; Revised 21 June 2005; Accepted 8 September 2005; Published online 26 January 2006.

Abstract

Cyclic stretch is known to alter a number of cellular and subcellular processes, including those involved in nonviral gene delivery. We have previously shown that moderate equibiaxial cyclic stretch (10% change in basement membrane area, 0.5 Hz, 50% duty cycle) of human pulmonary A549 cells enhances gene transfer and expression of reporter plasmid DNA in vitro, and that this phenomena may be due to alterations in cytoplasmic trafficking. Although the path by which plasmid DNA travels through the cytoplasm toward the nucleus is not well understood, the cytoskeleton and the constituents of the cytoplasm are known to significantly hinder macromolecular diffusion. Using biochemical techniques and immunofluorescence microscopy, we show that both the microfilament and microtubule networks are significantly reorganized by equibiaxial cyclic stretch. Prevention of this reorganization through the use of cytoskeletal stabilizing compounds mitigates the stretch-induced increase in gene expression, however, depolymerization in the absence of stretch is not sufficient to increase gene expression. These results suggest that cytoskeletal reorganization plays an important role in stretch-induced gene transfer and expression.