Evaluation of Arterial Impairment after Experimental Gelatin Sponge Embolization in a Rabbit Renal Model

OBJECTIVE Arterial stenosis is a major obstacle for subsequent interventional procedures. We hypothesized that the stenosis is caused by gelatin sponge embolization and performed an experimental study in a rabbit renal model. MATERIALS AND METHODS A total of 24 rabbits were embolized with porcine gelatin sponge particles injected into the renal arteries. Four rabbits were sacrificed on 1 day, 4 days, 1 week, 2 weeks, 3 weeks, and 4 weeks after embolization. Microscopic evaluations were performed on hematoxylin-eosin and smooth muscle actin immunohistochemical stained sections. RESULTS Gelatin sponge particles were mainly observed in the segmental and interlobar arteries. Transmural inflammation of the embolized arterial wall and mild thickening of the media were observed 1 week after embolization. Resorption of the gelatin sponge and organization of thrombus accompanied by foreign body reactions, were observed from 2 to 4 weeks after embolization. Microscopic images of the 3 weeks group showed vessel lumens filled mostly with organized thrombi, resulting in severe stenosis. Additionally, vessels showed a thickened intima that contained migrating smooth muscle cells and accompanying interruption of the internal elastic lamina. The migrating smooth muscle cells were distributed around the recanalized arterial lumen. CONCLUSION Gelatin sponge embolization may induce arterial stenosis by causing organized thrombus and intimal hyperplasia, which consists of migrating smooth muscle cells and intimal collagen deposits.