Chronic Pulsatile Shear Stress Alters Insulin-Like Growth Factor-I (IGF-I) Binding Protein Release In Vitro
- Cite this article as:
- Elhadj, S., Akers, R.M. & Forsten-Williams, K. Annals of Biomedical Engineering (2003) 31: 163. doi:10.1114/1.1540637
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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 dynes/cm2) and high (23±8 dynes/cm2) 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 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.
PAC2003: 8719Uv, 8715La, 8719Rr, 8714Ee, 8716Dg