Comparison of complement consumption and platelet accumulation between membrane oxygenators coated with a polymer or heparin

Abstract

Introduction The membrane oxygenator in extracorporeal circulation circuits is coated with acrylate-copolymer (ACP) or immobilized heparin (IHP) to enhance hemocompatibility. To evaluate the relative features of both coatings, we compared blood components circulated in the circuits with ACP-and IHP-coated membranes in vitro using whole human blood. Methods Whole human blood was heparinized and circulated in two experimental circuits with an ACP-coated reservoir, tubes, and an ACP- or IHP-coated membrane. Platelet (PLT) counts and the amount of total protein (TP), complement component 3 (C3), and complement component 4 (C4) were measured at 0, 8, 16, 24, and 32 h in each experiment ( n = 5). Results The PLT count at 0-h circulation was lower in the IHP-coated than in the ACP-coated circuits ( p = 0.034); however, no significant difference was observed at other time points. Reduction in TP at 8-h and 16-h circulation and in C3 at 32-h circulation was lesser in the ACP-coated than in the IHP-coated circuits ( p = 0.004, 0.034, and 0.027, respectively); reduction in TP and C3 at other time points and C4 at each time point was not significantly different. There were significant interactions between coating type and circulation duration in the PLT, TP, and C3 transitions ( p = 0.008, 0.020, and 0.043, respectively). Conclusions Our findings suggest that ACP-coated membranes can prevent the initial drop in PLT count and C3 consumption over 32 h, whereas IHP-coated membranes could not prevent this drop in extracorporeal circulation. Therefore, ACP-coated membranes are suitable for short- and long-term extracorporeal life support.

Platelet volume indices and von Willebrand factor levels in blood exposed to polymer- or heparin-coated membrane oxygenators

“…With respect to the coating types, our prior study using a comparable experimental circuit revealed that an initial drop in platelet counts, indicating a temporary decrease immediately upon the commencement of circulation, was observed in the IHP circuit, thereby affirming the hemocompatibility of IHP. 13 However, the results of VWF in the present study suggest that IHP can inhibit platelet activation more effectively than ACP can. When considering the treatment of patients with ECC, it may be more beneficial to prevent VWF attenuation rather than focusing on the initial drop, as the latter typically normalizes spontaneously.…”

“…Reports on platelet activation in ECC circuits in clinical settings are doubtful because the data obtained from clinical settings are significantly affected by the type or condition of the disease or individual patient requirements. 13 Because this study was performed under appropriate conditions to eliminate confounding factors, it precisely demonstrated platelet activation in blood exposed to the circuit surface of ECC. In fact, this study had several concerns that the blood left from the human body is attenuated and does not work properly, suggesting that the data in this study cannot be directly accepted for clinical settings.…”

“…When considering the treatment of patients with ECC, it may be more beneficial to prevent VWF attenuation rather than focusing on the initial drop, as the latter typically normalizes spontaneously. 13,37 Further validation using diverse data sets and a thorough evaluation are necessary to determine which coating more effectively mitigates platelet activation.…”

“…However, temporary accumulation of platelets tended to occur in the circuit with a heparin-coated membrane. 13 Nonetheless, in that study, because the materials indicating platelet activation were not tested and only platelet counts were measured, the details of platelet activation in ECC were still unclear. Here, we aimed to clarify the platelet activity in blood in contact with the coating surface on the ECC circuit.…”

“…We hypothesized that polymer coating has several advantages in hemocompatibility and examined the differences between heparin and polymer coatings. 12,13 One of these examinations suggested that the time transitions in the reduction of platelet counts in blood circulating through circuits with both heparin-and polymer-coated membrane oxygenators were comparable. However, temporary accumulation of platelets tended to occur in the circuit with a heparin-coated membrane.…”