Resident | Clinician Scientist Charité - Universitätsmedizin Berlin | Berlin Institute of Health Berlin Institute of Health, Germany
Purpose: The effectivity, in vivo visualizability and biocompatibility of newly developed, loadable, potentially bioresorbable, monodisperse microspheres for embolotherapy based on PMMA hydrogels were evaluated in a rabbit renal model.
Material and Methods: The microparticles of modifiable electric charge were provided as anionic particles in a diameter of 300 µm with a loading capacity for kationic substrates of up to 40 % mass fraction and were tagged with 1% magnetite by the manufacturer. Particle embolization of an interlobar artery via a 2F microcatheter was carried out in 24 rabbits. Contrast enhanced (CE) magnet resonance imaging (MRI) was performed afterwards to demonstrate magnetite deposition and renal perfusion defects. The rabbits were sacrificed after follow-up angiography and MRI in cohorts of 8 animals each after 7, 28 or 56 days. Pathologic changes to the renal parenchyma, signs of particle degradation and vessel recanalization were evaluated histologically and angiographically.
Results: The embolizations via mirocatheters were technically successful. Three animals had to be sacrificed prematurely due to complications not related to the renal embolization. The wedge-shaped perfusion defects on angiography corresponded in shape and size with infarcts and magnetite depositions observed in CE T1w and native T2w MRI sequences respectively. Although the particles exhibited signs of in vitro degradability when suspended in serum, no clinically relevant particle degradation or vessel recanalization was seen across the different time points. There was very little, heterophilic cellular infiltrate or vascular inflammation consistent with high biocompatibility.
Conclusions: The newly developed, monodisperse and loadable microparticles based on PMMA hydrogels are easy to handle and effective embolization agents with good biocompatibility. Recent advances in the reduction of chemical cross-linking to just a tenth encourage further in vivo testing of degradability.