| Objective: To investigate the embolic effectiveness and mechanism of targeting embolization of the suspension from magnetic microspheres with Lipiodol (S-Fe3O4-Lp) by transcather renal arterial embolization of rabbit's kidneys. Materials and Methods: 1. Evaluate the suspending ability of five size of magnetic microsphere which average diameter is 50μm, 100μm, 15μm, 200μm, and 250μm respectively by test of the falling speed in lipiodol. Scan appearances of 250μm magnetic microspheres by scanning electron microscope (SEM) and obtained this kind of microspheres's falling speed when they mixed with lipiodol in different proportions (50mg: 1ml, 100mg: 1ml, 150mg:1ml). 2. In vitro, select 250μm magnetic microspheres to mix with lipiodol in the propotion of 100mg:1ml and examine whether this mixture can go through the 3-6F catheter. 3. In animal experiments, fifteen healthy NewZealand rabbits were divided into two groups at random to conduct a comparative study, with 10 for the experimental group that received the right renal arterial embolization with the suspension of 250μm magnetic microspheres with lipiodol, 5 for the control group which underwent the same embolization with lipiodol. Analyses of the two group's experimental results were based on abdominal piain fime, renal arteriography and histopathologic study of the embolized and unembolized kidneys, heart, lung, liver after sacrifice 3 day, 1, 2, 4, 6, or 8 week after embolization. The serum iron, liver and renal functionalchanges of the two group animals were observed at the same intervals. Results: 1. Five size of magnetic microsphere not only can be suspended in lipiodol but keep suspending situation for a relative long time. The average time when they fall 10% in lipiodol are 120, 85, 60, 45, 30min and the average falling speed are 0.32, 0.45, 0.87, 0.91, 1.20 cm/h respectively (P<0.001) . 250μm S -Fe3O4-Lp can go through the 3-6F catheter smoothly. 2. The pathological and renal arteriography results showed in the embolic effectiveness the experimental group is superior to the control group. The suspension produced more necrosis than did lipiodol. 3. 250μm magnetic microspheres and lipiodol showed significant positive correlation (P<0.005, r=0.76) in occluded arteries including renal glomeruli and intelober artery. Changes in the density of embolized kidneys by abdominal piain fime showed a significant difference after 2, 4, 6 week between the experimental group and the control group (P2<0.05, P3<0.05). No significant changes were observed in 1 week (P1>0.05). 4. The serum iron and liver, renal functional changes manifested no significant difference with pre-operation level after embolization with the suspension of 250μm magnetic microspheres and lipiodol (P>0.05).Conclusion: 1. The suspension of 250μm magnetic microspheres with lipiodol showed a good embolic effectiveness by transcather renal arterial embolization of rabbit's kidneys because the 250μm magnetic microspheres can block arteries at microvascular level, which simultaneously prevent blood draining lipiodol effectively. 2. During the whole course of emboliztion, 250μm magnetic microspheres can keep suspending in lipiodol all the time and move together into the embolized small arteries in the end. This is the key mechanism for the suspension to targeting embolization.The suspension of 250μm magnetic microspheres with lipiodol with easy achievement, release from 3-6F cather and follow-up can be as a long-time, targeting embolic agent for clinical applications. |
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