Evaluation of Phospholipidic Surface Coatings ex-vivo

Abstract

To evaluate the thromboresistant properties of phospholipidic surface coatings mimicking the lipid surface of blood cells, we studied four different types of phospholipids bound onto PVC tubings in comparison to uncoated as well as heparin bonded controls. The samples analyzed included diacetylenic phospholipid coated as a monomeric treatment (A), diacetylenic phospholipid polymerised prior to being coated (B), and two types of polymeric phospholipids made using methacrylate containing monomers (C and D). A bovine (bodyweight 67 ± 3 kg) left heart bypass model (pump flow 3.2 ±0.1 l/min) was selected and the surfaces were exposed to the blood stream up to 360 min without systemic heparinization. Thereafter another set of samples was exposed to stagnant blood over 20 min. Besides hemodynamic, hematologic and biochemical analyses, the macroscopic appearance of 119 blood exposed surface samples was graded semiquantitatively on a scale of 0 to 10: no macroscopic deposits = grade 0, 1 spot (1 mm diameter) = grade 1, 2 spots = grade 2, 5 or more spots = grade 5, up to 10% of the surface covered with clots = grade 6, 100% covered = grade 10 (p<0.05=∗): mean grade of deposits was 0.0 ± 0.0 for segments perfused and 0.0 ± 0.0 for segments exposed to stagnant blood with surfaces exposing to the blood either heparin, phopholipid A, or phospholipid B (NS). Phospholipids C and D were graded 0.0 ± 0.0 if perfused and 0.7 ± 1.2 if exposed to stagnant blood. Uncoated PVC control tubings however were graded 0.2 ± 0.8 for segments perfused and 2.7 ± 3.0 for segments exposed to stagnat blood (p<0.05 in comparison to all surfaces coated with phospholipids or heparin if perfused and if exposed to stagnant blood). Hence phospholipidic surface coatings expose significant antithrombotic properties which out perform todays standard for tubings in clinical perfusion (uncoated PVC).