Effects of biaxial deformation on pulmonary artery endothelial cells

Abstract

An apparatus has been designed to subject vascular cells grown on a compliant substrate in vitro to uniform, quantifiable levels of biaxial deformation. The system described can be controlled with respect to strain level, rate, and frequency to mimic the pulsatile force to which vascular cells are exposed in vivo under both physiologic and pathologic conditions. In the experiments presented here, bovine pulmonary artery endothelial cells were grown on a substrate of segmented polyurethane urea (Mitrathane). Cell growth and morphology on this substrate were compared with those of cells grown on standard tissue culture polystyrene with no difference noted between the two substrates. Primary cultures of pulmonary artery endothelial cells were seeded onto Mitrathane, which was then subjected to cyclic biaxial deformation-producing strains of 0.78%, 1.76%, 4.9%, or 12.5% at a frequency of 1 sec-1 and a duty cycle of 0.5 sec-1 for 7 h. Cells subjected to deformations generating strains of either 4.9% or 12.5% secreted significantly less fibronectin than nondeformed cells. Similar results were obtained in experiments using cloned pulmonary artery endothelial cells on Mitrathane subjected to the 4.9% strain; however, total protein synthesis was increased. Cell viability and DNA synthesis were not affected by cyclic biaxial deformation in these experiments.

Mechanical stretch upregulates proteins involved in Ca2+ sensitization in urinary bladder smooth muscle hypertrophy

“…The cells were grown on a type I collagen-coated silicon membrane (Specialty Manufacturing, Saginaw, MI). Mechanical deformation of the cells was performed using a Tensorcell III, a device designed to apply precise and reproducible biaxial strains (supplied by CT Group, Crested Butte, CO) to the membrane on which the cells were grown (18). It has previously been shown that the cells experience essentially the same deformations as the substrate on which they are grown (5).…”

“…For experimental wells, biaxial strain was applied by stretching the elastic membrane cyclically for 24 and 48 h to provide 2.5% strain. Details of the strain level estimation, the design of the Tensor stretch instrument, and computer program are based on published data (18,48). The strain level of 2.5% was used in this study because this condition was found to be sufficient to produce molecular changes without inducing apparent cell injury (12).…”

Adaptation of the endothelium to fluid flow: in vitro analyses of gene expression and in vivo implications

“…V ascular M edicine 2004; 9: [35][36][37][38][39][40][41][42][43][44][45] portion of a vessel. 40 Regions proximal to and in the throat of the stenosis experienced time-averaged, uniform normal and high shear, respectively, while immediately distal to the stenosis, complex, non-uniform ow patterns that included ow separation, stagnation points, low laminar ow and eddy currents were observed.…”

“…144,145 In fact, the expression of IL1R L1 and TN F receptorassociated factor-3 (TRAF -3), two LSS-upregulated genes, has been implicated in the inhibition of Toll-like receptors (TLR4 and TLR1) and CD40, respectively, two signaling pathways implicated in in ammation and atherosclerosis. 59,145 V ascular M edicine 2004; 9: [35][36][37][38][39][40][41][42][43][44][45] Endothelial differentiation induced by LSS: sculpting the phenotypic response It has been hypothesized that uid ow acts as a differentiative stimuli to modulate endothelial phenotype=function. This hypothesis can be viewed on two levels.…”

“…These in vitro gene expression pro ling studies have identi ed a number of key molecular pathways that may be implicated in creating an anti-apoptotic, anti-proliferative, antioxidant =anti-in ammatory and pro-differentiative endothelial phenotype. Directed analyses of individual molecular cascades, in an attempt to recapitulate this gene expression ngerprint, may facilitate the discovery of novel thera-V ascular M edicine 2004; 9: [35][36][37][38][39][40][41][42][43][44][45] peutic targets that protect the vasculature and promote endothelial health and homeostasis. The future development of therapeutic strategies that preserve and=or restore endothelial health may have a profound impact on the natural history and treatment of vascular diseases, and signi cantly improve the lives of patients suffering from these diseases.…”