Chronic Pulsatile Shear Stress Alters Insulin-Like Growth Factor-I (IGF-I) Binding Protein Release In Vitro

Author: Elhadj Selim  

Publisher: Springer Publishing Company

ISSN: 0090-6964

Source: Annals of Biomedical Engineering, Vol.31, Iss.2, 2003-02, pp. : 163-170

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Abstract

Insulin-like growth factor-I (IGF-I) is a potent smooth muscle cell mitogen indicated to have a role in vascular disease. IGF-I stimulates proliferation via receptor activation but its activity is mediated by IGF binding proteins (IGFBPs). Since hemodynamics have been linked to vascular proliferative disorders, we studied how pulsatile low (5±2 \text{dynes/cm}^{2})</i> and high (23±8 \text{dynes/cm}^{2})</i> shear stresses impacted IGFBP metabolism in bovine aortic endothelial cells using the Cellmax capillary system. We modeled the pulsatile flow in our system using the Womersley model for flow inside a rigid tube and harmonic analysis revealed that the flow was sinusoidal with a frequency of ∼0.3 Hz for both shear stress treatments. Laminar flow was confirmed and the phase lag between the pressure and the flow found to be insignificant. Thus, our study provides a necessary characterization of this In Vitro</i> system as well as an investigation into how shear impacts the IGF axis. We found a significant difference in IGFBP distribution between treatments and, given that IGFBPs regulate IGF-I activity and that IGF-I-independent activities have been suggested for IGFBP-3, suggest that shear stress may indirectly regulate IGF-I activity, and, by extension, the effect of IGF-I on vascular pathologies. © 2003 Biomedical Engineering Society.</i> PAC2003: 8719Uv, 8715La, 8719Rr, 8714Ee, 8716Dg

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