Intravascular tissue reactions induced by various types of bioabsorbable polymeric materials: correlation between the degradation profiles and corresponding tissue reactions.
BACKGROUND
Several different bioabsorbable polymeric coil materials are currently used with the goal of improving treatment outcomes of endovascular embolization of intracranial aneurysms. However, little is known about the correlation between polymer degradation profiles and concomitant tissue responses in a blood vessel. The authors describe in vitro degradation characteristics of nine different polymeric materials and their corresponding tissue responses induced in rabbit carotid arteries.


METHODS
Mass loss and molecular weight loss of nine commercially available bioabsorbable sutures were evaluated in vitro up to16 weeks. The same nine materials, as well as platinum coils, were implanted into blind-end carotid arteries (n = 44) in rabbits, and their tissue reactions were evaluated histologically 14 days after the implantation.


RESULTS
Five of the nine polymers elicited moderate to strong tissue reactions relative to the remaining materials. While polymer mass loss did not correlate with their histologic findings, polymers that showed a faster rate of molecular weight loss had a tendency to present more active tissue reactions such as strong fibrocellular response around the implanted material with a moderate inflammatory cell infiltration. Maxon exhibited the fastest rate of molecular weight loss and poly-l-lactic acid the slowest.


CONCLUSIONS
The rate of molecular weight loss may be an important factor that is associated with the degree of bioactivity when bioabsorbable polymers are implanted into blood vessels. For further quantitative analysis, additional experiments utilizing established aneurysm models need to be conducted.
Division of Interventional Neuroradiology, Department of Radiological Sciences, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095-1721, USA. iyuki@mednet.ucla.edu
Ichiro
I
Yuki
Naoyuki
N
Uchiyama
Yuichi
Y
Murayama
Yih-Lin
YL
Nien
Daniel
D
Lee
Masaki
M
Ebara
Akira
A
Ishii
Alexander
A
Chiang
Harry V
HV
Vinters
Ichiro
I
Nishimura
Benjamin M
BM
Wu
Fernando
F
Vinuela
D020341:Absorbable Implants / Q000009:adverse effects*; D000818:Animals; D017536:Carotid Artery, Common / Q000187:drug effects* / Q000473:pathology*; D004621:Embolization, Therapeutic / Q000009:adverse effects* / Q000295:instrumentation*; D011108:Polymers / Q000009:adverse effects*; D011817:Rabbits; D013223:Statistics as Topic; D013537:Sutures / Q000009:adverse effects*
D011108:Polymers