A biodegradable stent based on poly(L-lactide) and poly(4-hydroxybutyrate) for peripheral vascular application: preliminary experience in the pig.
OBJECTIVE
To assess the technical feasibility and biocompatibility of a novel stent based on poly(L-lactide) (PLLA) and poly(4-hydroxybutyrate) (P4HB) for peripheral vascular applications.


METHODS
A polytetrafluoroethylene aortobi-iliac graft was implanted in 5 pigs through a midline abdominal incision. After transverse graft limb incision, 5 PLLA/P4HB stents and 5 metal stents (316L stainless steel) were randomly deployed at both iliac anastomotic sites with 6-mm balloon catheters. Angiography was performed to determine patency prior to sacrifice at 6 weeks. Stented segments were surgically explanted and processed for quantitative histomorphometry. Vascular injury and inflammation scores were assigned to the stented iliac segments.


RESULTS
No animals were lost during follow-up. All PLLA/P4HB stents were deployed within 2 minutes by balloon inflation to 8 bars without rupture of the stent struts or anastomotic suture. All stents were patent on postprocedural angiography. Histological analysis showed no signs of excessive recoiling or collapse. PLLA/P4HB stents demonstrated decreased residual lumen area and increased neointimal area after 6 weeks (12.27+/-0.62 and 8.40+/-1.03 mm(2), respectively) compared to 316L stents (13.54+/-0.84 and 6.90+/-1.11 mm(2), respectively) as the result of differences in stent areas (PLLA/P4HB: 4.31+/-0.15 mm(2); 316L: 2.73+/-0.29 mm(2)). Vascular injury scores showed only mild vascular trauma for all stents (PLLA/P4HB: 0.41+/-0.59; 316L: 0.32+/-0.47). Inflammatory reaction was slightly higher around PLLA/P4HB stent struts (1.39+/-0.52) compared to 316L (1.09+/-0.50).


CONCLUSIONS
Rapid balloon expansion of PLLA/P4HB stents is feasible without risk of strut rupture. PLLA/P4HB stents provide adequate mechanical stability after iliac anastomotic stenting in pigs. Smaller residual luminal areas in the PLLA/P4HB stents might have been caused by tissue ingrowth into the larger strut interspaces due to higher strut thickness (stent area) in this group. This limitation needs to be addressed in future work on the stent design.
Bünger
Carsten Michael
CM
Department of Surgery, University of Rostock, Germany. carsten.buenger@medizin.uni-rostock.de
Grabow
Niels
N
Sternberg
Katrin
K
Goosmann
Martin
M
Schmitz
Klaus-Peter
KP
Kreutzer
Hans J
HJ
Ince
Hüseyin
H
Kische
Stefan
S
Nienaber
Christoph A
CA
Martin
David P
DP
Williams
Simon F
SF
Klar
Ernst
E
Schareck
Wolfgang
W
D000714:Anastomosis, Surgical; D000818:Animals; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D001027:Aortography; D001672:Biocompatible Materials; D002404:Catheterization; D005240:Feasibility Studies; D005260:Female; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008670:Metals; D023421:Models, Animal; D010865:Pilot Projects; D011091:Polyesters / Q000737:chemistry*; D011474:Prosthesis Design; D012107:Research Design; D015607:Stents; D013552:Swine; D014654:Vascular Patency
D001672:Biocompatible Materials; D008670:Metals; D011091:Polyesters; C107955:poly(4-hydroxybutanoate); C033616:poly(lactide)