Abstract 502: Assessment and Characterization of Clot Using Scanning Electro Microscopy ‐ SEM : Beyond Conventional Histology

Introduction/Purpose While conventional histology offers limited insights, scanning electron microscopy (SEM) delivers high‐resolution images of the internal structure of the thrombus. We evaluated the feasibility and cytoarchitectural comparability of an animal‐derived blood model to human LVO thrombi using SEM. Material/Methods We generated in vitro clots from bovine whole blood using specific fibrin to red blood cell (RBC) compositions, including 25% fibrin/75% RBC and 90% fibrin/10% RBC formulations. Human LVO clots were retrieved during endovascular procedures and placed in a preservative solution within 1 hour of extraction. Subsequently, they were fixed in 2.5% glutaraldehyde, dehydrated in graded ethanol, and processed by critical point drying (CPD) before undergoing SEM examination. Qualitative analyses evaluating fibrin content, clot architecture, and overall composition was performed. Outcomes included cellular composition predominance and qualitative shell‐core organization. Results SEM of in vitro bovine clots showed pronounced compositional heterogeneity ( Figure 1 ), with network organization tracking the preset fibrin: RBC ratios; no discrete peripheral shell was identified in these animal clots. In contrast, human thrombi, one cardioembolic and one atherosclerotic, both exhibited a well‐organized fibrin‐platelet outer shell that enveloped the clot surface and was clearly distinguishable from the inner core (Figure 2). Internally, human clots showed no significant differences in RBC content, whereas bovine clots reflected deliberate ratios. Instead, human thrombi only exhibited a subtle clustering of fibrin fibers in the internal core. Quantitatively, fibrin fiber diameter was smaller in human thrombi than in bovine clots (0.94 μm 0.69‐1.09 vs 1.46 μm 1.28‐1.71). Conclusion SEM showed clear differences between animal and human thrombi, with human clots consistently forming a compact fibrin‐platelet shell that defines architecture and may modulate influence response to thrombolysis and potentially impact thrombectomy techniques. image image