Size and morphological analysis of albumin microspheres in the lungs and liver of mice

Abstract

Albumin microspheres containing magnetite (mean diameter 1.10 ± 0.85 μm; range 0.1–6.0 μm when hydrated in the injection medium) were injected into the tail vein of male mice. Mice were killed at intervals and microspheres, collected from their lungs and liver by magnet, were examined for the microsphere size and also used for morphological observation. No significant differences were found between microspheres lodged in the lungs and liver in the mean diameter and size distribution, showing 1.85 ± 1.55 and 1.24 ± 0.90 μm at 1 h post-injection, respectively. The mean diameters of microspheres lodged in the lungs and liver were dependent on their residence time. Temporary increases in the mean diameter were observed between 1 h and 1 day in both organs, in the lungs by 31.7% and in the liver by 44.4%, respectively. During the following period of 6 days, the size of the microspheres in the lungs decreased gradually, and, in contrast, in the liver the size decreased rapidly. The cavity formation and surface damage probably from the hydration and attack of enzyme in the living tissue could be observed on the surface of microspheres collected from mice.