In vivo thrombus formation induced by complement activation on polymer surfaces.

Area of Science:

• Biomaterials Science
• Immunology
• Polymer Chemistry

Background:

• Thrombus formation on medical implants is a significant clinical challenge.
• Understanding the role of the complement system in biomaterial-induced thrombosis is crucial for developing improved materials.

Purpose of the Study:

• To investigate the relationship between in vitro complement activation and in vivo antithrombogenicity of various polymer surfaces.
• To elucidate the role of complement activation, specifically C5a(des Arg), in leukocyte adhesion and thrombus formation on polymer surfaces.

Main Methods:

• In vitro complement activation assays were performed on polyethylene (PE) tubes modified with acrylamide (AAm), acrylic acid (AC), 2-hydroxyethyl methacrylate (HEMA), N-vinylpyrrolidone (NVP), and vinyl alcohol (VOH).
• In vivo antithrombogenicity and cell adherence were evaluated in canine peripheral veins.
• The effect of inhibiting complement activation (using naja haje cobra venom factor) on leukocyte adhesion and thrombogenesis was assessed.

Main Results:

• Polymer surfaces that strongly activated complement in vitro (NVP, VOH) exhibited increased leukocyte adhesion and thrombogenicity in vivo compared to low-activating surfaces (AAm, PE, HEMA).
• Inhibition of complement activation significantly reduced leukocyte adhesion and thrombogenesis on the NVP surface.
• Acrylic acid (AC) surfaces showed inconclusive in vitro activation but behaved similarly to VOH in vivo.

Conclusions:

• Complement activation on polymer surfaces plays a significant role in initiating thrombus formation.
• Leukocyte activation mediated by C5a(des Arg) appears to be a key mechanism linking complement activation to thrombus formation on biomaterials.
• These findings have implications for the design of more biocompatible polymeric materials for medical applications.