Measurement of friction-induced changes in pig aorta fibre organization by non-invasive imaging as a model for detecting the tissue response to endovascular catheters

Alterations in quantity or architecture of elastin and collagen fibres are associated with some blood vessel pathologies. Also some medical interventions such as endovascular catheterization have the potential to damage blood vessels. This study reports the use of porcine aorta as a model system for studying the physical impact of catheters on vasculature, in conjunction with non-invasive imaging techniques to analyse collagen and elastin fibre organization and assess load-induced changes. Porcine aorta was exposed to frictional trauma and elastin and collagen fibre orientation evaluated by destructive, histochemical methods and non-invasive imaging. The latter allowed the immediate impact of force on fibre orientation and fibre recovery to be evaluated longitudinally. In normal aorta, elastin fibres are aligned at the surface, but become less aligned with increasing depth, showing no alignment by ~30 µm. Collagen fibres meanwhile appear aligned down to a depth of 35 µm. Changes in collagen and elastin fibre orientation in healthy pig aorta were detected by conventional destructive histology within 5 minutes of application of a sliding 10N load, while lesser loads had less impact. Good recovery of fibre orientation was observed within 20 minutes. Non-invasive imaging of ex vivo aorta tissue provides a good indication of the extent of fibre re-organization following frictional stress, at loads similar to those encountered during medical interventions such as catheterization. These results indicate that tissue deformation can occur from these procedures, even in healthy tissue, and highlight the potential for the development of an in vivo probe capable of monitoring vascular changes in patients.