A Water-Based Liquid Embolic: Evaluation of its Safety and Efficacy in a Rabbit Kidney Model

To evaluate a novel aqueous-based liquid embolic (Embrace Hydrogel Embolic System, [HES]) that has been developed to embolize hypervascular tumors by filling the tumor vascular bed and solidifying into a hydrogel. HES was evaluated for embolization safety and efficacy relative to microspheres in a preclinical rabbit kidney model.

A renal embolization model in New Zealand white rabbits was utilized. Twenty-four rabbits underwent unilateral kidney embolization via the main renal artery with either HES or 40-μm microspheres. Twenty-two rabbits survived the procedure and were monitored for 2, 12, 17.5, or 26 weeks before sacrifice. All rabbits underwent a repeat renal angiogram before necropsy. HES was evaluated for nontarget embolization, safety, and embolization effectiveness as measured by recanalization and viability of embolized tissue.

Both embolization materials were found to be safe, with targeted tissue necrosis and absence of nontarget embolization. Prenecropsy angiograms found vascular recanalization in 0/14 (0%) HES-embolized kidneys and in 3/8 (38%) microsphere-embolized kidneys (P = .036). Viable kidney tissue was observed in 2/14 (14%) kidneys embolized with HES and 5/8 (63%) kidneys embolized with microspheres (P = .052). All kidneys embolized with microspheres that showed vascular recanalization had viable tissue on histological sections. HES was observed in vessels as small as 10 μm in diameter in histological analysis.

HES provided deep, durable vascular bed embolization that resulted in less recanalization and, on an average, less viable target tissue compared with 40-μm microspheres. No systemic effects or nontarget tissue embolization was identified.