Abstract No. 483 - Radiopaque, bioresorbable embolic microspheres: an animal study to demonstrate feasibility and short term data

Abstract

Our study provides experimental data on new embolic microspheres with dual properties: bioresorbability and radiopacity. Using conventional angiographic techniques, the radiopaque, bioabsorbable embolic microspheres (BREMS) were characterized in an animal model. BREMS, a polyestercarbonate co-polymer of tyrosine analogs and polyethylene glycol, were suspended in saline only (sizes: 90-180, 180-300, or 400-700µm dia.) then delivered through an angiographic catheter (2.8F microcatheter or 4F Cobra catheter) after selective catherization of the renal arteries (bilateral, lower pole) in a naïve Yucatan model (N=8 animals, 15 kidneys). Kidneys were examined on 0, 30 and/or 60 days. A Siemens Artis Zee equipped with 3D DynaCT was used for visualization at the 60 day termination. Kidneys were evaluated post-mortem for gross changes. Samples were then prepared to assess the presence of residual BREMS using x-ray and micro-computed tomography (MCT, X-Tek Hawk) and prepared for histopathology. Day 0: In vivo, the completeness of embolization with BREMS was immediately, visually evident, without the use of contrast agent. The radiopacity allowed excellent control during the procedure and non-target embolization did not occur. Post-mortem x-rays and MCT confirmed the region-specific embolization and the depth and homogeneous, spatial distribution of BREMS. Small microspheres (90-300µm dia.) occluded the arteries from the pelvis to the cortex. Larger BREMS (400-700µm dia.) occluded the lobar and interlobar arteries with a sparse distribution in interlobular arteries. Days 30 and 60: Fluoroscopic views with contrast and 3D DynaCT showed a region specific arrest of blood supply accompanied by notable tissue atrophy. At the time of this abstract, MCT and histology processing is underway (data pending). Bioabsorbability and vessel recanalization is currently being evaluated. The radiopacity of BREMS allowed immediate, in vivo visual monitoring of region-specific embolization. The feasibility of these embolic microspheres was proven without the use of radiographic dye. Pathologic evaluation is currently being performed.