title: A novel platform for in situ investigation of cells and tissues under mechanical strain.
abstract: The mechanical micro-environment influences cellular responses such as migration, proliferation, differentiation and apoptosis. Cells are subjected to mechanical stretching in vivo, e.g., epithelial cells during embryogenesis. Current methodologies do not allow high-resolution in situ observation of cells and tissues under applied strain, which may reveal intracellular dynamics and the origin of cell mechanosensitivity. A novel polydimethylsiloxane substrate was developed, capable of applying tensile and compressive strain (up to 45%) to cells and tissues while allowing in situ observation with high-resolution optics. The strain field of the substrate was characterized experimentally using digital image correlation, and the deformation was modeled by the finite element method, using a Mooney-Rivlin hyperelastic constitutive relation. The substrate strain was found to be uniform for >95% of the substrate area. As a demonstration of the system, mechanical strain was applied to single fibroblasts transfected with GFP-actin and whole transgenic Drosophila embryos expressing GFP in all neurons during live imaging. Three observations of biological responses due to applied strain are reported: (1) dynamic rotation of intact actin stress fibers in fibroblasts; (2) lamellipodia activity and actin polymerization in fibroblasts; (3) active axonal contraction in Drosophila embryo motor neurons. The novel platform may serve as an important tool in studying the mechanoresponse of cells and tissues, including whole embryos.
authors.affiliation: Department of Mechanical Sciences & Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801, USA.
authors.forename: W W
authors.initials: WW
authors.lastname: Ahmed
authors.forename: M H
authors.initials: MH
authors.lastname: Kural
authors.forename: T A
authors.initials: TA
authors.lastname: Saif
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001369:Axons / Q000378:metabolism; D003198:Computer Simulation; D004331:Drosophila melanogaster / Q000196:embryology; D004625:Embryo, Nonmammalian / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology*; D020342:Finite Element Analysis; D000882:Haplorhini; D018625:Microscopy, Atomic Force; D009928:Organ Specificity; D011554:Pseudopodia / Q000378:metabolism; D022502:Stress Fibers / Q000378:metabolism; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D046509:Tissue Culture Techniques / Q000379:methods*
chemical_list: D000199:Actins