A rabbit model for efficacy evaluation of endovascular coil materials.
BACKGROUND
To investigate biomaterials seeking for their possible use for aneurysm treatment, in vivo screening tests using a number of potential materials are required. However, there is no established animal model that is suitable for such purpose. Some models require special preparation of tested materials for transcatheter delivery and others are inappropriate in view of their cost-effectiveness. The purpose of this study is to establish an animal model that overcomes these limitations and help us select potential materials before the preclinical evaluation.


METHODS
Bilateral CCAs in a rabbit were surgically ligated, and a 2-cm segment of either a bare platinum coil or a polymeric coil (a platinum coil coated with PLGA 10/90) was implanted into each blind-ended arterial segment (n = 26). They were harvested at day 1, 7, 10, 14, or 30, respectively. Angiographic and histologic evaluations as well as quantitative analysis on the development of the organized thrombus were performed.


RESULTS
One day after the implantation, both platinum and PLGA coils were surrounded by immature thrombus that was induced by blood flow stagnation in the arterial segment. At day 7, minimal thrombus organization was observed around both types of materials. At postimplantation days 10 and 14, fibrocellular responses, the early findings of the thrombus organization process, were observed in both material groups. Such histologic findings were more prominent in the PLGA coil group as compared to the platinum coil group (day 10, P = .051; day 14, P = .011). Well-organized thrombus was observed in both material groups at day 30 without showing statistical difference (P = .12).


CONCLUSIONS
Given the cost-effectiveness, the simple material preparation process, and its feasible histologic evaluation methods, this new animal model can be useful in screening other potential biomaterials for the development of new coil devices.
Ebara
Masaki
M
Department of Neurosurgery, The Jikei University School of Medicine, Tokyo 105-8471, Japan.
Yuki
Ichiro
I
Murayama
Yuichi
Y
Saguchi
Takayuki
T
Nien
Yih-Lin
YL
Vinters
Harry V
HV
Vinuela
Fernando
F
Abe
Toshiaki
T
D015901:Angiography, Digital Subtraction; D000818:Animals; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology; D002533:Cerebral Angiography; D020099:Coated Materials, Biocompatible; D004195:Disease Models, Animal; D004621:Embolization, Therapeutic / Q000295:instrumentation*; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D019344:Lactic Acid; D008422:Materials Testing; D010984:Platinum; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011817:Rabbits; D016896:Treatment Outcome; D014654:Vascular Patency / Q000502:physiology
D020099:Coated Materials, Biocompatible; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D010984:Platinum