Hydroxyapatite coating of detachable coils for endovascular occlusion of experimental aneurysm

Abstract

The purpose of this study was to evaluate the effect of hydroxyapatite (HAp) coating on Guglielmi detachable coils (GDCs) in an experimental aneurysm model. A total of 12 aneurysms were experimentally made in the common carotid arteries of swine using a microsurgical technique. Embolization was done on these aneurysms using standard GDCs and GDCs coated with HAp (GDC-HAp). The animals were then killed 14 days after embolization. The physical properties of coated coils and the development of tissue scarring and coverage the aneurysm's orifice were evaluated macroscopically and microscopically. Macroscopically, a scar formation and coverage at the neck of aneurysms were observed in a group with GDC-HAp, while such findings were not seen in a group with GDC. With light microscope, fibroblasts were seen in the neck of the aneurysms in a group using GDC-HAp, whereas only a fibrin- like net was seen in a group using GDC. In a group with GDC-HAp, inflammatory response was more intense in the dome of the aneurysm with faster re-endothelial coverage of the neck of the aneurysm than the ones in a group with GDC. These results indicated that GDC-HAp might create a clinically beneficial biological surface in an experimental aneurysm model.

Figure 1

A schema of Hydroxyapatite coating is shown. The platinum plate is coated by alternate soaking.

Figure 2

Scanning electron-microscopic appearances of surface of platinum plate (upper) and Hydroxyapatite coated platinum plate (lower) (original magnification, x5000). Note the califlower-like appearance of hydrozyapatite crystals on the surface.

Figure 3

Using a microscope, a 5-mm-long arterectomy was performed and a side wall aneurysm was created by venoarterial end-to side anastomosis.

Figure 4

Angiograms of experimental aneurysms created on bilateral common carotid arteries and occluded aneurysms with GDC-HAp. After tight packing of aneurysms, complete occlusion was recognized 2 weeks later.

Figure 5

Macroscopic appearances of an aneurysmal orifice 14 days after treatment, with standard GDC and GDC-HAp. Surfaces of standard GDCs were covered with fibrin-like materials. On the other hand, the orifice of GDC-HAp treated aneurysm was covered with thick fibrous tissue.

Figure 6

Light microscopic findings in a region of the aneurysm sac. The aneurysm sac treated with GDC-HAp was filled with fibroblasts and monocytes (lower). Fibrin nets were seen with standard GDC (upper), whereas a microscopic mild fibroblast growing was seen in the aneurysmal dome with GDC-HAp.