12-Month Coronary Angiography, Intravascular Ultrasound and Histology Evaluation of a Novel Fully Bioabsorbable Poly-L-Lactic Acid/Amorphous Calcium Phosphate Scaffolds in Porcine Coronary Arteries

Our previous studies have confirmed the superior biocompatibility of the poly-L-lactic acid/amorphous calcium phosphate (PLLA/ACP) scaffolds (PowerScaffold (R)) compared to PLLA scaffolds and their similar 6-month radial strength compared with TAXUS (R) stents. In order to conduct further dynamic observations on the performance of the PowerScaffold (R) after 12-month implantation compared with the TAXUS (R) stents. Twenty PowerScaffold (R) and 20 TAXUS (R) were implanted in porcine coronary arteries. At 12-month follow-up, Quantitative Coronary Angiography showed that the stent reference vessel diameter (3.19 +/- 0.25 mm vs. 2.75 +/- 0.22 mm, p < 0.05), the mean lumen diameter (3.07 +/- 0.22 mm vs. 2.70 +/- 0.17 mm, p < 0.05) and the late lumen gain (0.45 +/- 0.07 mm vs. 0.06 +/- 0.06 mm, p < 0.01) were all significantly greater with the PowerScaffold (R) than the TAXUS (R). As well, Intravascular Ultrasound showed the stent reference vessel area (7.74 +/- 0.48 mm(2) vs. 6.96 +/- 0.51 mm(2), p<0.05), the mean stent area (7.49 +/- 0.46 mm(2) vs. 6.53 +/- 0.47 mm(2), p < 0.05) and the mean lumen area (7.22 +/- 0.50 mm(2) vs. 6.00 +/- 0.48 mm(2), p < 0.01) were all significantly greater with the PowerScaffold (R) than the TAXUS (R). The luminal patency rate of the PowerScaffold (R) significantly increased from 72.45 +/- 6.84% at 1 month to 93.54 +/- 8.15% at 12 months (p < 0.01) while the TAXUS (R) stents were associated with a nonsignificant decreasing trend (89.44 +/- 8.44% vs. 86.53 +/- 8.22%). Pathology indicated the average thickness of the struts degraded by 14.25 +/- 3.04 mu m at 1 month, 23.39 +/- 2.45 mu m at 6 months and 35.54 +/- 2.20 mu m at 12 months. Immunohistochemical examination showed that the expression of inflammatory factors NF-kappa B gradually decreased from 1 -month to 12-month (36.79 +/- 4.78 vs. 5.79 +/- 2.85, P < 0.01). As the late lumen gain of arteries implanted with the PowerScaffold (R) increases over time with the growth of vessels, it effectively reverse the late vascular negative remodeling observed with the TAXUS (R) stents, providing a better option for lumen restoration treatment in clinical practice.