Ultrastructural characterization of surface‐induced platelet activation on artificial materials by transmission electron microscopy

Abstract

Platelet adhesion is one of the most pivotal events of blood clotting for artificial surfaces. However, the mechanisms of surface-induced platelet activation have not been fully been elucidated or visualized so far. In this study, we attempted to observe the internal structures and adhesion interfaces of human platelets attached to artificial surfaces by transmission electron microscopy (TEM) during the platelet activation process. We prepared observation samples by a conventional embedding method using EPON 812 resin. The sectioning was sliced perpendicular to the a-platelet/material interface. Observation by TEM indicates that internal granules coalesce in the center of the platelet accompanied by pseudopodial growth in the early stage of platelet activation. Pseudopodia from a platelet attach to the material interface not along a plane but at a point. In addition, along with the process of platelet activation, the gap between the platelet membrane and the material surface at the interface disappeared and a-platelet/material adhesion became much tighter. In the fully activated platelet stage, the platelet becomes thinner and tightly adheres to the substrate. As a result of comparative observation of an adherent platelet on polycarbonate (PC) and on amorphous carbon (a-C:H), it was found that internal granules release was inhibited more remarkably on a-C:H coating rather than on PC. Despite numerous technical difficulties in preparing sectional samples, such a study might prove the essential mechanism of biomaterial-related thrombosis, and it might become possible to modify the surfaces of materials to minimize material-related thrombosis.

Platelet Function During Cardiopulmonary Bypass Using Multiple Electrode Aggregometry: Comparison of Centrifugal and Roller Pumps

“…This study was conducted with CP, which is made of polycarbonate and PVC tubing. Platelet activation has been reported at platelet-polycarbonate interfaces, with transmission electron microscopy showing changes in the internal structures and adhesion interfaces of activated platelets (27). Scanning electron microscopy showed that platelets attached to PVC surfaces, and Chandler loop analysis showed that PVC increased the numbers of circulating platelets positive for CD62P, a marker of platelet activation (28).…”

Hematologic concerns in extracorporeal membrane oxygenation

“…The etiology of platelet dysfunction on ECMO is complex and has not yet been definitively elucidated. The artificial surface from the ECMO circuit may induce platelet activation and adhesion 64 . Shear stress may contribute to platelet activation and may also contribute to loss of platelet surface receptors necessary for adhesion 65,66 .…”

Poly(2-methacryloyloxyethyl phosphorylcholine) (MPC) nanofibers coated with micro-patterned diamond-like carbon (DLC) for the controlled drug release

“…The activation levels of the attached platelet could be classified as follows [14]: (I) an early stage of adhesion of an original spherical platelet, (II) the development of pseudopodia from the attached platelet, and (III) the fully-spread platelet. The morphology of the attached platelets on PC and MPC fibers after 60 min of incubation is shown in Fig.…”