Experimental evaluation of early and long-term effects of microparticle embolization in two different mini-pig models. Part II: liver.

PURPOSE: To evaluate trisacryl-gelatin microspheres (40-120 microm) for acute and chronic tissue embolization in mini-pig livers.

METHODS

Thirteen animals were divided into four groups: group 1 (n = 3), total arterial bed occlusion with acute procedure; groups 2 to 4, chronic superselective embolization with follow-up of 1 week (group 2, n = 1), 4 weeks (group 3, n = 4) or 14 weeks (group 4, n = 5). Key endpoints were homogeneity and particle distribution in acute embolizations (group 1) and necrosis and inflammation in chronic embolizations (groups 2-4) as assessed microscopically and angiographically.

RESULTS

After liver embolization, parenchymal necrosis did not occur; only signs of vessel wall disintegration were evident. The bile ducts remained intact. A distinct foreign body reaction with sparse leukocytic infiltration and giant cells was found at 14 weeks, but no signs of major inflammation were found. Particles were seen at the presinusoidal level, but no particle transportation into the sinusoids was observed.

CONCLUSIONS

Embolization in mini-pig livers, using small trisacryl-gelatin microspheres, results in vessel fibrosis without parenchymal or bile duct necrosis. The most likely explanation for preservation of the parenchyma is portal inflow. Small trisacryl-gelatin microspheres may be ideal as an adjunct for chemoembolization.