Poly-l-lactic acid/amorphous calcium phosphate bioabsorbable stent causes less inflammation than poly-l-lactic acid...

Poly-l-lactic acid (PLLA) based bioabsorbable stents with or without amorphous calcium phosphate (ACP) were implanted and compared the inflammation in coronary arteries.

6 PLLA and 6 PLLA/ACP based paclitaxel-eluting stents were randomly implanted into the coronary arteries of 12 healthy mini-pigs. The segments with stent were used to evaluate inflammation score and endothelialization score by hematoxylin-eosin staining.

At the 28th day after stent implantation, no in-stent restenosis or stent thrombosis was found in both PLLA and PLLA/ACP group. Histological analysis indicated that the inflammation score in PLLA/ACP group was less than that of in PLLA group (2.20±0.42 vs. 2.80±0.48, P<0.05). Consist with that, the expression of NF-κB was lower in PLLA/ACP group. The results from immunohistochemistry showed that the expressions of endothelial nitric oxide synthase (eNOS) and CD 31 in PLLA/ACP group were dramatically higher than those in PLLA group respectively. The serum levels of vascular endothelial growth factor (VEGF) and nitric oxide (NO) in PLLA/ACP group were significantly higher than those in PLLA group respectively (509.86±49.37 pg/ml vs. 322.04±35.16 pg/ml and 139.46±7.52 μmol/L vs. 29.55±16.55 μmol/L, P<0.05).

The application of ACP helps to reduce the inflammation caused by PLLA, and is also helpful in endothelial formation and function for PLLA-based bioabsorbable stent.