Interaction of activated leukocytes with polymeric microspheres

Area of Science:

• Biomaterials Science
• Immunology
• Polymer Chemistry

Background:

• Polymeric particles are used in medical devices, necessitating evaluation of their biocompatibility.
• Leukocyte activation during cardiopulmonary bypass can alter interactions with foreign materials.
• Surface wettability is a key factor influencing particle-leukocyte interactions.

Purpose of the Study:

• To investigate the phagocytosis and adhesion of polymeric particles with varying surface wettabilities to leukocytes.
• To compare particle-leukocyte interactions before, during, and after cardiopulmonary bypass (CPB).

Main Methods:

• Production of three types of 1.5-microm polymeric particles: PMMA, P(MMA/HEMA), and PMMA/PVAL, differing in surface wettability.
• Incubation of particles with blood samples from patients undergoing CPB.
• Quantification of particle phagocytosis and adhesion by monocytes and neutrophils.

Main Results:

• Poly(methylmethacrylate) (PMMA) particles showed significant adhesion (14±4/monocyte, 11±3/neutrophil) in pre-bypass samples.
• P(MMA/HEMA) and PMMA/PVAL particles exhibited minimal adhesion pre-bypass.
• During CPB, PMMA particle adhesion increased, and P(MMA/HEMA) and PMMA/PVAL particles also adhered to or were phagocytosed by activated leukocytes.
• Leukocyte activation markers returned to baseline within 24 hours post-CPB.

Conclusions:

• Surface wettability critically influences the interaction of polymeric particles with leukocytes.
• Leukocyte activation during CPB enhances the adhesion and phagocytosis of previously non-interactive particles.
• Careful selection of biomaterials with appropriate surface properties is crucial for minimizing adverse immune responses during CPB.