Background and Purpose Much literature speaks to the reorganization of the ‘chronic thrombus’ within the body, with resulting changes in its cellular and molecular makeup. In contrast, little is known about more acute changes in composition of stroke thrombi from onset of symptoms to reperfusion

Materials and Methods Quantitative proteomes were generated using mass spectrometry from thromboembolic material from 59 AIS patients retrieved by mechanical thrombectomy. Clinical data, including the time since last known well (LKW) was gathered by retrospective chart review. Proteomic composition of material retrieved from patients within 6hr tLKW was compared with material collected after 6hr tLKW. Spearman correlations were used to describe associations between the abundance of individual proteins and tLKW. Gene ontology analysis and KEGG pathway analysis was further performed on all proteins with abundances associated with increased tLKW.

Results A total of 2,790 proteins were reliably (present in >80%) identified across all samples, and thus included for analysis. Clots collected > 6hr and < 6hr tLKW were strongly enriched in 13 and 5 proteins, respectively (|log₂fold-change| > 0.5, p < 0.05). Numerous proteins were negatively and positively associated with tLKW (Spearman’s; 0.25 < |ρ| < 0.46). GO tags associated with RNA and protein metabolism were over-represented in the set of proteins associated with increased tLKW (p_adj < 0.05). The most significantly represented KEGG pathways involve tRNA synthesis and amino acid metabolism (p_adj < 0.05)..

Conclusions This study points, for the first time, to differences in the proteomic landscapes between thrombi from AIS patients that are related to time since symptom onset. Taken together, the present data support a view of the stroke thrombus as a living, dynamic microenvironment with increasing intracellular protein and RNA processing with increased tLKW. More work is required to further characterize early and late stroke thrombi, as a changing clot landscape may directly underlie responsiveness to treatment.

Disclosures S. Akkipeddi: None. R. Rahmani: None. N. Ellens: None. G. Kohli: None. D. Schartz: None. S. Chittaranjan: None. T. Bhalla: None. T. Mattingly: None. C. Morrell: None. M. Bender: None.