Xanthan/Tween Solutions Improve Clot Preservation and Support Stroke Research

Introduction/Purpose Preservation of blood clot pathology is essential for advancing ischemic stroke research. Accurate characterization of clot composition provides insight into stroke etiology and informs treatment strategies, particularly when combined with prethrombectomy imaging. However, studies report contradictory results on the relationship between clot etiology and biology; this is partly because clots are commonly transported in 0.9% saline, which causes red blood cell (RBC) loss and alters clot structure. These artifacts reduce reproducibility and obfuscate the relationships between clot biology, imaging features, and outcomes. To address this, we evaluated how transport conditions alter clot composition and tested a novel xanthan/Tween blood‐mimicking solution as an alternative to saline for preserving clot integrity. Materials/Methods Two experiments were conducted. In Experiment 1, RBC‐rich and fibrin‐rich clots were prepared from sheep blood using the Chandler loop method. To simulate transport, clots were either (a) agitated on an orbital shaker for 30 minutes at room temperature, then stored in 0.9% saline for 24 hours, (b) stored directly in saline for 24 hours without agitation, or (c) frozen immediately as unpreserved controls. All samples were embedded in OCT, cryosectioned, and stained with Martius Scarlet Blue (MSB) to visualize RBCs, fibrin, platelets, and white blood cells (WBCs). Quantification was performed with ORBIT image analysis. In Experiment 2, RBC‐rich clots were placed in 1.5 mL Eppendorf tubes, agitated for 30 minutes, and then stored in air, 0.9% saline, or xanthan/Tween solution before identical processing and staining. Results In Experiment 1, agitation during saline storage caused significant RBC loss in RBC‐rich clots compared to both non‐agitated and fresh controls. No significant difference in composition was found between agitated and non‐agitated fibrin‐rich clots, reflecting their greater resistance to disruption. In Experiment 2, storage medium strongly influenced results. Clots stored in air appeared to have higher RBC percentages than fresh controls, likely reflecting mechanical compaction of RBCs into the core during agitation against tube walls rather than true preservation. In contrast, saline storage led to substantial RBC washout, as the low‐viscosity environment of saline allows RBCs to diffuse and detach more readily from the fibrin network. The xanthan/Tween solution preserved RBCs more effectively than saline, yielding values closer to those of freshly frozen clots. WBC and platelet percentages were stable across all conditions, while fibrin shifted inversely with RBCs. This reflects relative percentage changes: loss of RBCs increases the proportional contribution of fibrin to the clot matrix. Conclusions Clot type and transport conditions strongly influence measured clot composition. RBC‐rich clots are especially vulnerable to mechanical disruption and saline‐induced washout, which may lead to underestimation of cellular content. In contrast, fibrin‐rich clots are more resistant. The xanthan/Tween solution demonstrated superior preservation compared with saline, helping to retain RBC content and clot structure. Adoption of such a medium could minimize artifacts and help resolve conflicting pathology reports, strengthening correlations between clot biology, neuroimaging, and stroke etiology. Improved preservation methods have the potential to enhance the reliability of translational stroke research and support more accurate clinical decision‐making.