The behavior of biodegradable
polylactide as a
stent material has not yet been fully established in small vessels such as arteries with a diameter <3 mm. The aim of this study was to investigate the long-term effect of a copolymeric
polylactide (
PLA96)
stent. Appropriately sized spiral
PLA96 stents were implanted into the infrarenal aortas of 20 rabbits. Intraoperative systemic heparinization (150 IU/kg), perioperative subcutaneous enoxaheparin
sodium (10 mg),
ticlopidine (250 mg/day) for 1 month, and acetosalicylic
acid (12.5 mg/day) were continuously administered. Animals were euthanized according to a fixed timetable for up to 34 months for histologic and scanning-electron-microscopic assessment. Endothelialization was complete within 1 month. In 2 of the 3 aortas sampled 3 months after implantation, a mild inflammatory reaction was visible, with no sign of granulomatous or
foreign-body reaction in the vessel wall. Instead, in 1 sample examined at the same time point, neointimal chondroid
metaplasia was detected. After 6 months, inflammatory reaction declined in the vessel wall. Hydrolyzation of the
stent was histologically evident at 12 months, with mild
foreign-body reaction detectable in 2 of 5 aortas sampled at this time point. The
stent disintegrated without fragmentation by 24 months, as it was gradually replaced by
fibrosis. The vessel lumen remained patent at all time points. We conclude that the
PLA96 stent degraded with minimal tissue response within 24 months.
PLA96 may thus be a promising
stent core material for small vessels in the future, although further investigation is needed to establish its final biocompatibility.