Time course of stent endothelialization after intravascular radiation therapy in rabbit iliac arteries.
BACKGROUND
Late total occlusion after vascular brachytherapy (VBT) continues to be a serious complication. Delayed reendothelialization was suggested as a pivotal cause, but the time course for complete healing is unknown.


RESULTS
Seventy-two rabbit iliac arteries underwent stent implantation and were treated with gamma-radiation using 192Ir. The prescribed doses were 0 Gy (controls, n=24 arteries), 15 Gy (n=24), or 30 Gy (n=24) at 2 mm. Animals were killed at 1 month (n=24), 3 months (n=24), or 6 months (n=24) and were analyzed for histomorphometry or scanning electron microscopy. Intimal area was reduced after VBT at 3 months with 15 and 30 Gy (0.66+/-0.07 and 0.66+/-0.04 mm2, respectively) compared with controls (1.01+/-0.11 mm2, P<0.05) and at 6 months with 30 Gy (0.75+/-0.09 versus 1.28+/-0.26 mm2 in controls, P<0.01). Intimal area was similar at 6 months between 15 Gy and controls. At 1 month, 92+/-4% of the control stented segment was covered with endothelial cells, whereas only 37+/-4% and 37+/-8% was covered in the 15- and 30-Gy arteries, respectively. Similarly, at 3 and 6 months, there was a difference in the extent of reendothelialized areas (at 3 months, 95+/-2%, 32+/-12%, and 29+/-13%; and at 6 months, 98+/-2%, 40+/-8%, and 35+/-12% in control, 15-Gy, and 30-Gy arteries, respectively). Excess platelets and leukocytes were seen in irradiated arteries without complete coverage of endothelium.


CONCLUSIONS
Reendothelialization after VBT is not completed at 6 months after VBT. Special care with prolonged antiplatelet therapy should be considered beyond that time point.
Cheneau
Edouard
E
Cardiovascular Research Institute, Washington Hospital Center, 110 Irving St, NW, Suite 4B-1, Washington, DC 20010, USA.
John
Michael C
MC
Fournadjiev
Jana
J
Chan
Rosanna C
RC
Kim
Han-Soo
HS
Leborgne
Laurent
L
Pakala
Rajbabu
R
Yazdi
Hamid
H
Ajani
Andrew E
AE
Virmani
Renu
R
Waksman
Ron
R
D000818:Animals; D001918:Brachytherapy; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000502:physiology* / Q000648:ultrastructure; D005260:Female; D006083:Graft Occlusion, Vascular / Q000473:pathology / Q000532:radiotherapy*; D007083:Iliac Artery / Q000166:cytology / Q000473:pathology / Q000601:surgery*; D007700:Kinetics; D008297:Male; D011817:Rabbits; D011859:Radiography; D011879:Radiotherapy Dosage; D015607:Stents / Q000009:adverse effects*; D014945:Wound Healing