Date of Award

5-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biomedical Engineering and Sciences

First Advisor

Christopher A. Bashur

Second Advisor

Venkat Keshav Chivukula

Third Advisor

James R Brenner

Fourth Advisor

Linxia Gu

Abstract

Large vessel occlusion during acute ischemic strokes requires mechanical thrombectomy (MT) procedures using stent retrievers (SR). However, complete clot removal typically takes several attempts, which can amplify endothelial cell injury (EI). This project aims to characterize the extent of EI during MT using an in vitro vascular platform and a finite-element model (FEM). Impact of SR diameter and characterization of SR mechanical forces are assessed and correlated with human umbilical vein endothelial cell (HUVEC) response. HUVECs were seeded on fibronectin (4 µg/cm2) coated true-scale PDMS arterial phantoms with 2.5 mm luminal diameter. Test groups (n=6) either underwent a simulated MT using two different-sized clinical SRs (Trevo® XP PROVUE 3×20mm and 6×25 mm) or no MT (control). Phantoms were stained and imaged with fluorescence and SEM imaging to evaluate cell viability and function. FEM and mechanical testing found radial forces and shear stresses that were comparable, but exceeded stresses found in native blood flow. Fluorescent images showed significant decreases in cell confluency and area coverage after MT. The large and small SRs applied 220±12.3 and 16.7±5.78 mN forces, respectively, on a testing system with a 2.5 mm gap. SR shear forces were significantly higher for the large (87.8 mN) compared to the small (13.7 mN) SRs. The data showed significant increase in EI caused by MT. Similar EI between SR size was hypothesized as both SRs’ forces exceeding HUVECs survival threshold. Better understanding of the risks of EI after MT has the potential to improve the long-term success of MT surgeries.

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