Inhibition of neointimal proliferation with 188Re-labeled self-expanding nitinol stent in a sheep model.
OBJECTIVE
To evaluate a self-expanding rhenium 188 (188Re) radiochemically labeled radioactive stent in sheep.


METHODS
A self-expanding nitinol stent (30 mm in length, 8 mm in diameter) coated with a functionalized polymer layer was radiolabeled with 188Re. Fifty prostheses, 25 of which were radioactive (mean radioactivity, 20 MBq +/- 3.8 [SD]) and 25 of which were nonradioactive, were implanted into the external iliac arteries of 25 sheep. Stent patency was assessed with angiography. Neointimal formation was assessed with intravascular ultrasonography and histologic examination 1 month (in all sheep) and 3 months (in 12 sheep) after implantation. The results were analyzed by using repeated-measures analysis of variance with two repeated factors and paired t tests for comparison at each measuring point.


RESULTS
All stents were placed successfully. Data in one animal had to be excluded from the study. After 3 months, a mean neointimal area reduction of 70 mm2 +/- 55 (SD) was observed inside the radioactive stents, and a mean lumen reduction of 126 mm2 +/- 39 was observed inside the nonradioactive control stents (P =.022). An edge effect was observed in the radioactive stents in that they showed an amount of neointimal formation at the edges that was similar to that seen in control stents. This neointimal formation accounted for the maximum lumen loss in the vascular segment with the stent.


CONCLUSIONS
As compared with a nonradioactive stent, a beta particle-emitting stent, through endovascular irradiation, significantly inhibits neointimal formation inside the stent but not at the stent edges.
Meyer
Julius M A
JM
Department of Diagnostic Radiology, University of Technology, Pauwelsstrasse 30, Aachen D-52074, Germany.
Nowak
Bernd
B
Schuermann
Karl
K
Buecker
Arno
A
Moltzahn
Felix
F
Kulisch
Arthur
A
Heussen
Nicole
N
Görgen
Thomas
T
Büll
Udorich
U
Günther
Rolf W
RW
D000497:Alloys; D000818:Animals; D023903:Coronary Restenosis / Q000517:prevention & control; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D019919:Prosthesis Implantation; D011868:Radioisotopes / Q000627:therapeutic use*; D012211:Rhenium / Q000627:therapeutic use*; D012756:Sheep; D015607:Stents; D017539:Tunica Intima / Q000473:pathology / Q000528:radiation effects*
D000497:Alloys; D011868:Radioisotopes; C013616:nitinol; D012211:Rhenium