Purpose: This study aimed to compare the safety and efficacy of two resorbable microparticles in a porcine kidney model, focusing on recanalization and tissue injury outcomes over a 7-day follow-up period.
Methods: This exploratory proof-of-concept study included 10 pigs, each undergoing embolization of the upper polar arteries in both kidneys, resulting in 20 treated kidneys (10 per group). Angiographic evaluations were performed on all 20 treated kidneys (10 per group) across the 10 animals at immediate, 2-hour, 1-day, and 7-day post-embolization time points. Histopathologic evaluations were performed on 5 animals per group (5 kidneys per group). The primary endpoint was complete angiographic recanalization at 7 days. Secondary endpoints included early recanalization at 2 hours and 1 day and histopathologic tissue injury. In Group A, the right upper polar artery was embolized with spherical gelatin microparticles (Nexsphere-F®), whereas in Group B, the left upper polar artery was embolized with irregular microparticles (KIPZA®). Approximately 5-10 mL of microparticle suspension was injected per kidney; the mean embolization time per kidney was 30 ± 5 minutes.
Results: At 2 hours post-embolization, complete recanalization was observed in all Nexsphere-F kidneys and in 9 of 10 KIPZA kidneys; 1 KIPZA kidney showed partial recanalization. Full recanalization was observed in all kidneys by day 7. Histopathologic evaluation (5 kidneys per group) revealed no residual emboli or parenchymal infarction in Group A. In Group B, minimal microparticle residue and focal infarction (mean infarcted area 2.78% ± 1.33%) were observed, along with endothelial proliferation in arcuate and interlobular arteries.
Conclusion: In this exploratory pilot study, embolization with both Nexsphere-F and KIPZA microparticles resulted in early recanalization and minimal tissue injury. These proof-of-concept findings suggest that both microparticles may be suitable for temporary embolization when organ preservation is paramount, although larger powered studies with disease models and longer follow-up are needed.
Clinical significance: These preliminary data support the potential of resorbable microparticles for temporary embolization, emphasizing their use in scenarios requiring parenchymal preservation and underscoring the need for further research.
Keywords: Microparticles; angiography; embolic agent; embolization; organ preservation; therapeutic.