Biocompatibility of a new bioabsorbable radiopaque stent material (BaSO4 containing poly-L,D-lactide) in the rat pancreas.

Background/aim: During recent years, we have been developing bioabsorbable biliary stents with promising experimental results. In developing pancreatic stents before long-term experiments, the acute toxicity to the pancreas of a bioabsorbable, radiopaque polylactide (PLA 96-barium sulfate, BaSO4) stent material was investigated.

Methods: The pancreas of 65 Sprague-Dawley rats was exposed either to radiopaque stent material [PLA 96 with 25% (w/w) of BaSO4], radiolucent stent material (PLA 96), or inert steel by inserting a 5-mm-long (diameter 0.3 mm) fiber/stick of material into the pancreas after laparotomy under general anesthesia. Pancreatic tissue specimens and blood samples were taken after 1, 3, 7, and 21 days for histological examination and amylase activity measurements. Samples were also taken from 5 baseline (control) rats without exposing to any materials.

Results: The baseline serum amylase activity was normal, and no histological changes in the pancreas were observed. A significant increase (mean +/- SE) in the serum amylase activity was observed only on day 1 in the animals having radiopaque stent material (PLA 96-BaSO4; 5,845 +/- 1,135 U/l), steel (4,946 +/- 667 U/l), or radiolucent stent material (PLA 96; 7,684 +/- 667 U/l) inserted. There was slightly more acinar cell necrosis on day 7 in the steel group than in the radiopaque stent (PLA 96-BaSO(4)) group (p = 0.028).

Conclusions: Radiopaque stent material (PLA 96-BaSO4) was not more toxic than the reference steel material in the rat pancreas during the 21-day observation period and is thus applicable for further in vivo experiments when developing pancreatic bioabsorbable stents.