Accumulation of nano-sized particles in a murine model of angiogenesis

Abstract

PurposeTo evaluate the ability of nm-scaled iron oxide particles conjugated with Azure A, a classic histological dye, to accumulate in areas of angiogenesis in a recently developed murine angiogenesis model. Materials and methodsWe characterised the Azure A particles with regard to their hydrodynamic size, zeta potential, and blood circulation half-life. The particles were then investigated by Magnetic Resonance Imaging (MRI) in a recently developed murine angiogenesis model along with reference particles (Ferumoxtran-10) and saline injections. ResultsThe Azure A particles had a mean hydrodynamic diameter of 51.8±43.2nm, a zeta potential of −17.2±2.8mV, and a blood circulation half-life of 127.8±74.7min. Comparison of MR images taken pre- and 24-h post-injection revealed a significant increase in R2* relaxation rates for both Azure A and Ferumoxtran-10 particles. No significant difference was found for the saline injections. The relative increase was calculated for the three groups, and showed a significant difference between the saline group and the Azure A group, and between the saline group and the Ferumoxtran-10 group. However, no significant difference was found between the two particle groups. ConclusionUltrahigh-field MRI revealed localisation of both types of iron oxide particles to areas of neovasculature. However, the Azure A particles did not show any enhanced accumulation relative to Ferumoxtran-10, suggesting the accumulation in both cases to be passive.