Transient adhesion of platelets in pump-oxygenator systems: influence of SMA and nitric oxide treatments

Abstract

We employed gamma scintigraphy to quantify the transient accumulations of platelets in pump-oxygenator systems employed in cardiopulmonary bypass (CPB). A flat sheet microporous polypropylene membrane oxygenator (Cobe Duo) was employed, with and without siloxane/caprolactone oligomer coating (SMA) (n = 8 each). The effect of nitric oxide gas infusion on platelet deposition was also evaluated for the uncoated Cobe Duo system (n = 10 each). Scintigraphic images of radiolabelled cells were obtained and converted to numbers of all platelets, labeled and unlabeled, adhering to the pump and oxygenator surfaces. These numbers were compared, by study group, for a 90-min period of normothermic CPB in the adult pig, employing standard prime and anticoagulation regimens. Platelets adhered in large numbers to control oxygenators, reaching maxima (> 20% of the circulating platelet mass) 30 min following institution of CPB, and decreasing for the duration of CPB. SMA treatment significantly decreased platelet adhesion following a 5-10-min transient accumulation period. Nitric oxide infusion significantly reduced platelet adhesion throughout the CPB period. Platelet accumulations on the high fluid shear centrifugal pump surfaces increased monotonically to maxima at about the same time as for the oxygenators, but did not decrease thereafter. Higher platelet surface densities were observed on the centrifugal pump surfaces than on the oxygenator surfaces. CPB with the untreated circuit tended to reduce circulating platelet counts vs theoretical values based on hemodilution alone. In contrast, SMA significantly increased the circulating platelet count versus the untreated control group. These results indicate that platelet adherence to the foreign surfaces of CPB equipment are influenced in characteristic ways by time and fluid shear. SMA treatment and nitric oxide infusion both reduce platelet adhesion to oxygenator surfaces. SMA treatment spares these cells for the circulation.

Crystallization behavior and UV‐protection property of PET‐ZnO nanocomposites prepared by in situ polymerization

“…Surprisingly, platelet numbers rose at the end of the 2 h recirculation procedure in the uncoated system, suggesting that surface‐bound platelets were released back into the circulating blood. Similar results have been reported in a noninvasive gamma imaging study of platelet and PMN adhesion to pump‐oxygenator circuit surfaces in a pig normothermic ex vivo perfusion model 33. We could not observe this effect in the bioactive or biopassive coated systems (Figure 2).…”

Cardiopulmonary Bypass Copolymer Surface Modification Reduces Neither Blood Loss Nor Transfusions in Coronary Artery Surgery

“…SMA biomaterial treatment has been shown to enhance blood biocompatibility in vitro and in vivo [11,13,14]. Mainly, this effect is based on reduced antithrombogenicity, thus limiting plateletsurface interaction and subsequent platelet activation [11,15].…”

“…This technique consists of blending the SMA copolymers polycaprolactone (PCL) and polydimethylsiloxane (PDMS) with base polymer resins prior to processing at high temperature [12,13]. During processing, PCL and PDMS migrate to the polymer surface resulting in a PCL-PDMS-PCL triblock-copolymer layer of approximately 180 nm thickness, which has been shown to reduce platelet and leukocyte activation in vitro and in vivo [11,13,14]. Recently, two clinical studies by Gu et al [15] and Rubens et al [16] have shown that SMA preparation attenuates platelet-CPB circuit interaction and decreases both fibrinolysis and thrombin formation compared to untreated circuits.…”

Water as a Blood Model for Determination of CO2 Removal Performance of Membrane Oxygenators

“…Although great efforts have been made to improve the biocompatibility of oxygenator circuits [ 3 ], serious side effects occur due to contact of blood with the artificial polymer surfaces. These side effects ultimately include reduced platelet function and survival as well as prolonged bleeding times after perfusion [ 4 ]. Consequently, the optimization of oxygenators aims for increasing gas exchange efficiency while reducing the membrane surface and blood priming volume [ 5 ].…”