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.