Surface Modification of Biodegradable Polymers towards Better Biocompatibility and Lower Thrombogenicity

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Cardiovascular Engineering

Background:

• Drug-eluting stents (DES) utilize permanent polymeric coatings to prevent in-stent restenosis.
• Biodegradable polymers were developed for DES to mitigate thrombosis risks associated with early-generation devices.
• This study assesses biodegradable polymers for vascular stent coatings and fully bioabsorbable stents.

Purpose of the Study:

• Evaluate the biocompatibility of five biodegradable polymers for vascular stent applications.
• Investigate the impact of surface modifications on polymer biocompatibility.
• Assess the thrombogenicity of polymer surfaces.

Main Methods:

• Examined five biodegradable polymers: PLLA, PDLLA, P(LLA-co-GA), P(DLLA-co-GA), and P(LLA-co-CL).
• Applied wet-chemical (NaOH, EDA) and plasma-chemical (O2, NH3) surface modifications.
• Assessed biocompatibility using cytotoxicity assays on fibroblasts and endothelial cells (HCAEC, HUVEC).
• Evaluated cell morphology via CLSM and SEM, and thrombogenicity via hemocompatibility testing.

Main Results:

• Unmodified polymer surfaces showed poor endothelial cell viability and adhesion.
• Surface modifications positively influenced polymer biocompatibility.
• Ammonia plasma treatment consistently enhanced cell viability, adhesion, and morphology across all tested polymers.

Conclusions:

• Surface modification is a viable strategy to improve polymer biocompatibility for vascular applications.
• Plasma modification shows promise for enhancing stent re-endothelialization.
• Further research should focus on stabilizing plasma modifications and conjugating biomolecules for in vivo applications.