Evaluation of Long-Term Inflammatory Responses after Implantation of a Novel Fully Bioabsorbable Scaffold Composed of Poly-L-lactic Acid and Amorphous Calcium Phosphate Nanoparticles

Abstract EN

Objectives.

Our previous studies have confirmed the superior biocompatibility of the poly-L-lactic acid/amorphous calcium phosphate (PLLA/ACP) scaffolds compared to PLLA scaffolds at 1-month.

In the present study, the long-term inflammatory responses of PLLA/ACP scaffolds in a porcine coronary model have been explored.

Methods.

The 24 PLLA scaffolds and 24 PLLA/ACP scaffolds were implanted into the coronary arteries of 24 miniature pigs.

Serum levels of ALT, AST, and CRP were measured before operation, as well as 1-month, 6-months, 12-months, and 24-months.

The vascular segments were taken for pathomorphological observation.

HE staining was used for the inflammatory score and fibrosis score.

Immunohistochemical staining detected positive expression indexes of MMP-9 and NF-κB.

The expression of inflammation-related proteins of IL-1 and IL-6 was detected by Western Blot in surrounding tissues of scaffolds.

Results.

There was no significant difference between the two groups in ALT, AST, and UR at different time points (P<0.05).

The inflammation score in the PLLA/ACP group was lower than that in the PLLA group at 6-months, 12-months, and 24-months (P<0.05), and the fibrosis score was reduced in the PLLA/ACP group than that in the PLLA group at 12-months and 24-months (P<0.05).

The expression of MMP-9 and NF-κB in the PLLA/ACP group was significantly less than that in the PLLA group at 6-months, 12-months, and 24-months (P<0.05).

The protein expression of IL-1 in the PLLA/ACP group was decreased than that in the PLLA group at 12-months and 24-months (P<0.05).

Furthermore, the protein expression of IL-1 was significantly lower than that in the PLLA group at 6-months, 12-months, and 24-months (P<0.01).

Conclusions.

The supplement of ACP nanoparticles can effectively reduce the long-term inflammatory reaction caused by PLLA and has good safety and biocompatibility.

The novel bioabsorbable PLLA/ACP scaffold provides reliable guidance for the development and clinical application of bioabsorbable scaffolds in the future.