Non-invasive imaging of tissue-engineered vascular endothelium with iron oxide nanoparticles

Abstract

Tissue engineering pursues the development of strategies to repair, regenerate or replace damaged or diseased tissue. Successful preclinical applications in this field have been shown for different cardiovascular implants [1], [2]. The translation of tissue-engineered products into clinical rou-tine is often limited by the lack of suitable non-invasive imaging methods to visualize parameters and behaviour of the constructs. Long-term non-destructive monitoring may simplify animal and clinical trials and reduce the number of needed animals. Recent studies have focused on a wide spectrum of imag-ing modalities to evaluate their suitability for applications in tissue engineering. Nelson et al. [3] published a pilot study demonstrating the feasibility of MRI for the evalua-tion of tissue engineered vascular grafts (TEVG) perfor-mance in vivo. In this case, human aortic smooth muscle cells were labelled with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles. The cells were embedded in a small lumen TEVG and implanted into a mouse. The USPIO-labelled TEVG consistently appeared with sharper borders and registered lower T2 relaxation time values than the unseeded, unlabelled control scaffolds in vivo. In this study, fluorescently coated, ultrasmall superpara-magnetic iron oxide nanoparticles (FLUSPIO) were used as a contrast enhancement for magnetic MRI of endothelial cells at the cellular level. The FLUSPIO exposure time and concentration in the medium were optimized with respect to the long-term cell viability and detectable MRI signal. © 2012 by Walter de Gruyter Berlin Boston.