Biological response to expandable metallic stents implanted into the portal vein. A histomorphometric study.
BACKGROUND
This study was undertaken to investigate the biological response to an expandable metallic stent implanted in the canine portal vein with a special reference to the histomorphometric contribution of cellular and acellular elements to the intimal and medial growth.


METHODS
In 11 dogs, the Gianturco Z stent was placed into the portal vein and was harvested at intervals of 4 (n=6) and 12 weeks (n=5). In 6 dogs, the normal portal vein was harvested and used as a control. The specimens were subjected to histomorphometric examination.


RESULTS
Mean intimal/medial thickness and total intimal/medial area significantly increased progressively by 12 weeks. Collagen intimal/medial area also significantly increased progressively by 12 weeks, while smooth muscle intimal/medial area significantly increased at 4 weeks but did not change from 4 weeks to 12 weeks. Collagen density tended to increase at 4 weeks and significantly increased at 12 weeks, while smooth muscle density significantly decreased at 4 weeks and continued to decrease at 12 weeks.


CONCLUSIONS
The total area or mean thickness of the intima and media of the stented portal vein continued to increase by 12 weeks after stent placement. This phenomenon appeared to be due to proliferation of smooth muscle cells followed by accumulation of collagen.
Second Department of Surgery, Hokkaido University School of Medicine, Sapporo, Japan.
K
K
Miyazaki
T
T
Nishibe
S
S
Watanabe
F
F
Kudo
H
H
Katoh
K
K
Yasuda
T
T
Tanabe
D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects; D001807:Blood Vessel Prosthesis / Q000009:adverse effects; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation*; D002455:Cell Division; D004285:Dogs; D005549:Foreign-Body Reaction / Q000209:etiology / Q000473:pathology; D006975:Hypertension, Portal / Q000601:surgery; D008670:Metals / Q000009:adverse effects; D009131:Muscle, Smooth, Vascular / Q000473:pathology; D011169:Portal Vein / Q000473:pathology* / Q000601:surgery; D015607:Stents / Q000009:adverse effects; D017539:Tunica Intima / Q000473:pathology
D001672:Biocompatible Materials; D008670:Metals