Differences in proteomic composition of retrieved stroke emboli associated with susceptibility to in vitro thrombolysis

Saturday, September 9, 2023

8:20 AM – 8:40 AM EDT

Location: Constitution CDE

Speaker(s)

Sajal Medha K. Akkipeddi, BA (he/him/his)

Medical Student
University of Rochester Medical Center
Rochester, New York, United States

Discussant(s)

Scott J. Cameron, MD, PhD

Section Head Vascular Medicine
Cleveland Clinic Foundation
Solon, Ohio, United States

Co-Author(s)

RR

Redi Rahmani, MD

Department of Neurosurgery
University of Rochester Medical Center, United States
NE

Nathaniel R. Ellens, MD

Department of Neurosurgery
University of Rochester Medical Center, United States
DS

Derrek A. Schartz, MD

Department of Imaging Sciences
University of Rochester Medical Center, United States
LW

Logan M. Worley, BA

Medical Student
University of Rochester Medical Center, United States
SC

Siddharth Chittaranjan, BA

Medical Student
University of Rochester Medical Center, United States
TB

Tarun Bhalla, MD, PhD

Department of Neurosurgery
University of Rochester Medical Center, United States
TM

Thomas K. Mattingly, MD, MSc

Department of Neurosurgery
University of Rochester Medical Center, United States
MB

Matthew T. Bender, MD

Assistant Professor, Department of Neurosurgery, Cerebrovascular Division
University of Rochester Medical Center
Rochester, New York, United States

Description of Background: Fibrin, von Willebrand factor, and extracellular DNA from neutrophil extracellular traps (NETs) all contribute to AIS thrombus integrity. The understudied proteome of thrombi provides a quantitative avenue for exploring susceptibility to pharmacotherapy.

Methods: Thromboembolic material from 26 AIS patients retrieved by mechanical thrombectomy was portioned into four representative segments. A small piece of each representative segment was collected and pooled for mass spectrometry to generate a proteome for the corresponding thrombus. The remainder of the four segments were subjected to one hour of in vitro lysis at 37ºC in one of four lytic solutions with: the standard-of-care tissue plasminogen activator (T), tPA + von Willebrand factor-cleaving ADAMTS13 (TA), tPA + DNA-cleaving DNase I (TD), and all three enzymes (TDA). Post-lysis residual, characterized by the post-lysis thrombus weight as a percent of the pre-lysis weight, was compared across the four solutions. Spearman coefficients were used to describe the association between lysis and the abundance of each of 2,790 proteins identified by mass spectrometry.

Results: Post-lysis residual in the T condition was significantly greater than in the TD or TDA conditions (post-hoc Tukey, p < 0.01). Numerous proteins were strongly positively and negatively associated with lysis in each of the four lytic solutions. Notably, several histone protein signatures were associated with greater post-lysis residual in the T and TA conditions (Spearman’s ρ > 0.39 for all). However, these same proteins were associated with less residual in the t and TDA conditions (Spearman’s ρ < 0.40 for all).

Conclusion: This study demonstrates a synergistic effect of DNase and tPA in the in vitro lysis of stroke emboli. Proteomic analysis suggests that composition is directly associated with susceptibility to lysis. Specifically, DNA composition of clots, and thus NET load, is associated with decreased residual when subjected to DNase in addition to tPA, hinting at a potential pharmacologic target in the treatment of AIS.

Learning Objective: To investigate the proteomic composition of retrieved acute ischemic stroke (AIS) emboli as it relates to their susceptibility to thrombolysis by a variety of lytic agents.