Development of biodegradable radiopaque microsphere for arterial embolization-a pig study

Abstract

Aim: To develop a new type of calibrated, biodegradable, and imaging detectable microsphere and evaluated its embolization safety and efficacy on pig's liver and spleen.

Methods: Six kinds of pharmaceutical excipient were combined and atomized to form our microsphere. Twenty-four male Lanyu pigs weighing 25-30 kg were used. The arteries of spleen and liver were embolized with Gelfoam, Embosphere, or our microsphere. The serum biochemical tests, computed tomography (CT), liver perfusion scan, and tissue microscopy examination were done to evaluate the safety and efficacy of embolization.

Results: Radiopaque microspheres with a size ranging from 300 to 400 μm were produced. Embolization of hepatic and splenic artery of pigs with our microsphere significantly reduced the blood flow of liver and resulted in splenic infarction. The follow-up CT imaging and the microscopic examination showed intraarterial degradation of Gelfoam and microsphere. The blood tests demonstrated insignificant changes with regards to liver and renal functions.

Conclusion: Our microspheres, with the unique characteristics, can be used for transcatheter arterial embolization with effects equivalent to or better than Gelfoam and Embosphere in pigs.

Keywords: Arterial embolization; Atomization; Microsphere; Pharmaceutical excipient.

Figures

Figure 1

The microspheres in scanning electron microscope with a magnification of 150 ×.

Figure 2

The gross appearance and fluoroscopy picture of DC bead (left), Hepasphere (middle), and our microsphere (right).

Figure 3

The angiography of hepatic artery (A) and splenic artery (B).

Figure 4

The liver perfusion scan after our microsphere, Embosphere, or Gelfoam embolization showing blood flow reduced areas (green to blue areas) over the periphery of liver.

Figure 5

Serial non-enhanced computed tomography scans of pig’s liver taken on 4, 12, and 25 d after the microsphere embolization showing its radiopaque characteristic and the gradual fade along with time (white arrow).

Figure 6

Microscopic findings of liver showing intraarterial embolization materials (black arrow) and intact peripheral liver lobules (black arrow heads) after Gelfoam (A), Embosphere (B), or our microsphere (C) embolization (H-E stain, original magnification × 40).

Figure 7

Gross appearance of spleen after Gelfoam (A), Embosphere (B), or our microsphere (C) embolization showing various degree of infarction over the distal end of spleen.

Figure 8

Microscopic findings of spleen showing intraarterial embolization materials (arrow heads) and periarterial reactions after Gelfoam (A), Embosphere (B), or our microsphere (C) embolization (H-E stain, original magnification × 40). Note the degrading Gelfoam and our microsphere and the intact Embosphere at 28 d after the embolization.