Interaction of Vascular Smooth Muscle Cells with Collagen-Impregnated Embolization Coils Studied with a Novel Quantitative in Vitro Model
Todd Abruzzoa,
Harry J. Clofta,
Miroslav Marekc,
George G. Shengelaiaa,
Patrick B. Snowhille,
Sandra Miller Waldropb and
Athanassios Sambanisd
a Section of Interventional Neuroradiology, Emory University School of Medicine, Atlanta, GA
b Division of Radiological Sciences, Department of Radiology, Emory University School of Medicine, Atlanta, GA
c School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta
d School of Chemical Engineering and Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta
e Department of Pathology, Biomaterials Division, UMDNJ–Robert Wood Johnson Medical School, Piscataway, NJ
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FIG 1. Determination of the FS. Images are argon-laser fluorescence confocal micrographs of a CINC with a helical pitch of 250 µm obtained after monopulse exposure assay with an initial vascular smooth muscle cell (VSMC) concentration of 2.6 x 105 cells per milliliter (original magnification x40).
A, An oval ROI, represented by the white line, is manually drawn on the device surface to begin the analysis. Wide solid straight arrows indicate loops of the nitinol coil; curved arrows, collagen fibers; thin solid straight arrow, live cells; open arrow, dead cells.
B, A mask is applied to the image matrix outside the ROI, and the surface area within the ROI is calculated.
C, The live cell surface area within the ROI is calculated by subtracting red fluorescence and masking photon-deficient pixels within the ROI.
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FIG 2. Distribution of VSMCs on the surface of embolic devices. Images are argon-laser fluorescence confocal micrographs of embolic devices obtained after monopulse exposure assays (original magnification x40). Wide solid straight arrows indicate loops of the nitinol coil; curved arrows, collagen fibers; thin solid straight arrows, live cells; open arrows, dead cells.
A, CFBs exposed to an initial VSMC concentration of 2.6 x 104 cells per milliliter. VSMCs are spread over the convex surfaces of individual fibers and within the troughs between fibers.
B, Nitinol coils with a helical pitch of 50 µm exposed to an initial VSMC concentration of 2.6 x 105 cells per milliliter. VSMCs are preferentially distributed in the troughs between coil loops.
C, CINCs with a helical pitch of 250 µm exposed to an initial VSMC concentration of 2.6 x 105 cells per milliliter. VSMCs are focally concentrated on the surfaces of collagen fibers between consecutive coil loops.
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FIG 3. Mean FS of the device surface with VSMCs. The mean FS for each of the three devices studied are compared at three initial VSMC concentrations. The calculated mean FS is presented in the upper left margin above its corresponding bar. Error bars indicate a single standard deviation above and below the mean (n = 8). CINC-250 indicates CINCs with a helical pitch of 250 µm; NiT-50, nitinol coils with a helical pitch of 50 µm.
A, Initial VSMC concentration of 2.6 x 106 cells per milliliter.
B, Initial VSMC concentration of 2.6 x 105 cells per milliliter.
C, Initial VSMC concentration of 2.6 x 104 cells per milliliter.
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FIG 4. Adhesion coefficient plots for two trials of the monopulse exposure assays are presented for each device. The plot for trial 1 is a cluster of four diamonds, with a solid best-fit line. Each plot for trial 2 is a cluster of four squares, with a dashed best-fit line. The equation that represents the best-fit line and the correlation coefficient for the scatterplot are shown. On each graph, ln (1 - FSaverage) is plotted against the product of 1) the initial concentration of VSMCs, or [VSMC]i, that was used to conduct the monopulse exposure assay and 2) the interaction time t of 240 minutes (4 hours).
A, Plots for CFBs.
B, Plots for nitinol coils with a helical pitch of 50 µm.
C, Plots for CINCs with a helical pitch of 250 µm.
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