1370 Older Age of Thrombus is Associated With Proteomic Signatures of Greater Cytoskeletal Remodeling in Acute Ischemic Stroke

INTRODUCTION: It is known that a longer time since last known well (tLKW) is associated with worse outcomes in acute ischemic stroke (AIS). The thrombus itself has been described to undergo molecular changes over time, although this process of clot maturation and retraction has not been well-described in AIS. METHODS: Thromboembolic material was retrieved via mechanical thrombectomy from 57 AIS patients; comprehensive proteomes were obtained using mass spectrometry. tLKW and other clinical variables were collected from retrospective chart review. Thrombi were aged based on corresponding tLKWs. The relative protein abundances of younger and older thrombi as determined by tLKW were compared. Subsequent functional pathway analysis assessed the significance of differentially enriched proteins. A Spearman’s correlation between tLKW and number of passes was performed. RESULTS: 2,790 distinct proteins were identified across 57 thrombi. 5 and 14 proteins were differentially enriched in thrombi aged <6 hours (n=33) and =6 hours (n=24), respectively (|log2fold-change|>0.5, p<0.05). A separate comparison of the first (tLKW=120-186 minutes) and fourth quartiles (tLKW=623-1315 minutes) of tLKW revealed greater differences between thrombi, with 47 proteins enriched in Q4 (n=17), and 10 proteins enriched in Q1 (n=14) (|log2fold-change|>0.5, p<0.05). Functional analysis suggested that proteins enriched in Q4 thrombi are involved in cellular structure and cytoskeletal rearrangement (e.g., alpha-adducin, tropomodulin-1, dematin, etc.) (padj<0.05). tLKW is positively associated with a significantly greater number of passes required to retrieve thrombi (R=0.79, p=0.0004). CONCLUSIONS: This study describes significant proteomic differences between younger and older stroke thrombi, with a preponderance of cytoskeletal remodeling pathways represented in older thrombi. Proteomic data depicting the process of clot retraction, which is time dependent, could explain why older clots are often, as seen in this cohort, most technically difficult to retrieve.