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Structural hallmarks of stroke thrombi
A
B
C
Figure 1. Stroke thrombi typically consist of distinct red blood cell (RBC)-rich and platelet-rich areas. Consecutive thrombus sections were stained with Hematoxylin & Eosin (H&E), Martius Scarlet Blue (MSB) and an anti-platelet GPIbα antibody. Classical H&E staining (left) was used to visualize overall thrombus composition and organization. On H&E staining, RBC-rich areas appear red whereas RBC-poor areas appear light pink. On MSB staining (middle), red areas show the presence of fib- rin, whereas RBC appear yellow. Platelets were stained purple using an anti-GPIbα antibody (right). Overall, stroke thrombi consist of two distinct areas: RBC-rich areas (R), and platelet-rich areas (P). Examples of representative thrombi are shown, which are RBC-rich/platelet-poor (A), mixed (B), and RBC-poor/platelet-rich (C). Scale = 500 μm.
have instigated large scale implementation of endovascu- lar treatment, based on mechanical removal of the occlud- ing thrombus.4-9 These positive trials have shown the ben- efits of this approach, but also revealed procedural chal- lenges that can hamper efficient treatment. One of the most important obstacles in endovascular therapy is that thrombi tend to differ in consistency and removability. Indeed, mechanical thrombectomy is not successful in removing the thrombus in up to 20% of the patients.10 Beside vascular access, thrombus composition is consid- ered an important factor responsible for thrombectomy failure.10,11
In spite of the fact that the occluding thrombus is the primary target in both pharmacological and mechanical recanalization therapy, very little is known about the gen-
eral composition and structural organization of stroke thrombi or about the interplay between their cellular and molecular components. The main reason for this lack of knowledge was the unavailability of stroke thrombi in the past. However, endovascular thrombectomy procedures now provide patient thrombus material for detailed analy- sis.11
Good understanding of thrombus structure and compo- sition will be crucial to meet the pressing demand for improved pharmacological or endovascular recanalization efficiency in acute stroke treatment. An increasing number of studies have now started to report first insights into stroke thrombus composition, mostly based on Hematoxylin & Eosin (H&E) staining and looking at fibrin and red blood cells (RBC) only. However, more specific
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