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Fluid shear stress regulates the invasive potential of glioma cells via modulation of migratory activity and matrix metalloproteinase expression.

Qazi H, Shi ZD, Tarbell JM - PLoS ONE (2011)

Bottom Line: This was confirmed by RT-PCR and with the aid of MMP-1 and MMP-2 shRNA constructs.The models developed for this study imply that flow-modulated motility involves mechanotransduction of fluid shear stress affecting MMP activation and expression.These models should be useful for the continued study of interstitial flow effects on processes that affect tumor progression.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, City College of New York, City University of New York, New York, New York, United States of America.

ABSTRACT

Background: Glioma cells are exposed to elevated interstitial fluid flow during the onset of angiogenesis, at the tumor periphery while invading normal parenchyma, within white matter tracts, and during vascular normalization therapy. Glioma cell lines that have been exposed to fluid flow forces in vivo have much lower invasive potentials than in vitro cell motility assays without flow would indicate.

Methodology/principal findings: A 3D Modified Boyden chamber (Darcy flow through collagen/cell suspension) model was designed to mimic the fluid dynamic microenvironment to study the effects of fluid shear stress on the migratory activity of glioma cells. Novel methods for gel compaction and isolation of chemotactic migration from flow stimulation were utilized for three glioma cell lines: U87, CNS-1, and U251. All physiologic levels of fluid shear stress suppressed the migratory activity of U87 and CNS-1 cell lines. U251 motility remained unaltered within the 3D interstitial flow model. Matrix Metalloproteinase (MMP) inhibition experiments and assays demonstrated that the glioma cells depended on MMP activity to invade, and suppression in motility correlated with downregulation of MMP-1 and MMP-2 levels. This was confirmed by RT-PCR and with the aid of MMP-1 and MMP-2 shRNA constructs.

Conclusions/significance: Fluid shear stress in the tumor microenvironment may explain reduced glioma invasion through modulation of cell motility and MMP levels. The flow-induced migration trends were consistent with reported invasive potentials of implanted gliomas. The models developed for this study imply that flow-modulated motility involves mechanotransduction of fluid shear stress affecting MMP activation and expression. These models should be useful for the continued study of interstitial flow effects on processes that affect tumor progression.

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Fluorescence intensity of gels containing cells stained with Calcein to quantify cell distribution within the collagen suspension.(A) Fluorescence of horizontal slices (10 µm each) up to 130 microns above the filter for gels that were compacted, not compacted, and suspensions that were exposed to four hours of flow. The cell distribution in non-compacted gels was distinctive when compared to the compacted control and four-hour flow gels (# p<0.015). (B) Intensity of the 600 micron thick collagen suspensions (50 µm slices) to verify similar cell distribution of the compacted control and the experimental flow cases at 0.36 dynes/cm2 (low) and 0.55 dynes/cm2 (high) shear stress. Compacted control and flow cell suspensions utilized for the migration study had similar cell distributions (p≈0.8). In all cases, cells density increased towards the filter interface (p<0.0001). All cases were normalized to their respective average intensities and the data presented as mean±SEM.
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pone-0020348-g002: Fluorescence intensity of gels containing cells stained with Calcein to quantify cell distribution within the collagen suspension.(A) Fluorescence of horizontal slices (10 µm each) up to 130 microns above the filter for gels that were compacted, not compacted, and suspensions that were exposed to four hours of flow. The cell distribution in non-compacted gels was distinctive when compared to the compacted control and four-hour flow gels (# p<0.015). (B) Intensity of the 600 micron thick collagen suspensions (50 µm slices) to verify similar cell distribution of the compacted control and the experimental flow cases at 0.36 dynes/cm2 (low) and 0.55 dynes/cm2 (high) shear stress. Compacted control and flow cell suspensions utilized for the migration study had similar cell distributions (p≈0.8). In all cases, cells density increased towards the filter interface (p<0.0001). All cases were normalized to their respective average intensities and the data presented as mean±SEM.

Mentions: The collagen concentration of gels exposed to flow (sheared) and compacted (non-sheared) controls was 8.09±0.26 mg/ml-4 times more concentrated than the original gels before compaction. Compaction only affected cell distribution perpendicular to the filter (vertical direction); cells remained viable, morphologically normal, and well distributed in every horizontal plane throughout the thickness of the gels (Supplementary Fig. S1). The cumulative effect of compaction by flow through the gels was most apparent closer to the filter (Supplementary Fig. S2). The cell distribution of the compacted controls and the suspensions exposed to four hours of shear were similar, whereas the distribution of non-compacted controls was different from the compacted control and sheared cases (Fig. 2A). Following the flow period, the cell distribution of control suspensions compacted by ten minutes of flow, were similar to gels exposed to four hours of varied shear stress (Fig. 2B).


Fluid shear stress regulates the invasive potential of glioma cells via modulation of migratory activity and matrix metalloproteinase expression.

Qazi H, Shi ZD, Tarbell JM - PLoS ONE (2011)

Fluorescence intensity of gels containing cells stained with Calcein to quantify cell distribution within the collagen suspension.(A) Fluorescence of horizontal slices (10 µm each) up to 130 microns above the filter for gels that were compacted, not compacted, and suspensions that were exposed to four hours of flow. The cell distribution in non-compacted gels was distinctive when compared to the compacted control and four-hour flow gels (# p<0.015). (B) Intensity of the 600 micron thick collagen suspensions (50 µm slices) to verify similar cell distribution of the compacted control and the experimental flow cases at 0.36 dynes/cm2 (low) and 0.55 dynes/cm2 (high) shear stress. Compacted control and flow cell suspensions utilized for the migration study had similar cell distributions (p≈0.8). In all cases, cells density increased towards the filter interface (p<0.0001). All cases were normalized to their respective average intensities and the data presented as mean±SEM.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3102715&req=5

pone-0020348-g002: Fluorescence intensity of gels containing cells stained with Calcein to quantify cell distribution within the collagen suspension.(A) Fluorescence of horizontal slices (10 µm each) up to 130 microns above the filter for gels that were compacted, not compacted, and suspensions that were exposed to four hours of flow. The cell distribution in non-compacted gels was distinctive when compared to the compacted control and four-hour flow gels (# p<0.015). (B) Intensity of the 600 micron thick collagen suspensions (50 µm slices) to verify similar cell distribution of the compacted control and the experimental flow cases at 0.36 dynes/cm2 (low) and 0.55 dynes/cm2 (high) shear stress. Compacted control and flow cell suspensions utilized for the migration study had similar cell distributions (p≈0.8). In all cases, cells density increased towards the filter interface (p<0.0001). All cases were normalized to their respective average intensities and the data presented as mean±SEM.
Mentions: The collagen concentration of gels exposed to flow (sheared) and compacted (non-sheared) controls was 8.09±0.26 mg/ml-4 times more concentrated than the original gels before compaction. Compaction only affected cell distribution perpendicular to the filter (vertical direction); cells remained viable, morphologically normal, and well distributed in every horizontal plane throughout the thickness of the gels (Supplementary Fig. S1). The cumulative effect of compaction by flow through the gels was most apparent closer to the filter (Supplementary Fig. S2). The cell distribution of the compacted controls and the suspensions exposed to four hours of shear were similar, whereas the distribution of non-compacted controls was different from the compacted control and sheared cases (Fig. 2A). Following the flow period, the cell distribution of control suspensions compacted by ten minutes of flow, were similar to gels exposed to four hours of varied shear stress (Fig. 2B).

Bottom Line: This was confirmed by RT-PCR and with the aid of MMP-1 and MMP-2 shRNA constructs.The models developed for this study imply that flow-modulated motility involves mechanotransduction of fluid shear stress affecting MMP activation and expression.These models should be useful for the continued study of interstitial flow effects on processes that affect tumor progression.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, City College of New York, City University of New York, New York, New York, United States of America.

ABSTRACT

Background: Glioma cells are exposed to elevated interstitial fluid flow during the onset of angiogenesis, at the tumor periphery while invading normal parenchyma, within white matter tracts, and during vascular normalization therapy. Glioma cell lines that have been exposed to fluid flow forces in vivo have much lower invasive potentials than in vitro cell motility assays without flow would indicate.

Methodology/principal findings: A 3D Modified Boyden chamber (Darcy flow through collagen/cell suspension) model was designed to mimic the fluid dynamic microenvironment to study the effects of fluid shear stress on the migratory activity of glioma cells. Novel methods for gel compaction and isolation of chemotactic migration from flow stimulation were utilized for three glioma cell lines: U87, CNS-1, and U251. All physiologic levels of fluid shear stress suppressed the migratory activity of U87 and CNS-1 cell lines. U251 motility remained unaltered within the 3D interstitial flow model. Matrix Metalloproteinase (MMP) inhibition experiments and assays demonstrated that the glioma cells depended on MMP activity to invade, and suppression in motility correlated with downregulation of MMP-1 and MMP-2 levels. This was confirmed by RT-PCR and with the aid of MMP-1 and MMP-2 shRNA constructs.

Conclusions/significance: Fluid shear stress in the tumor microenvironment may explain reduced glioma invasion through modulation of cell motility and MMP levels. The flow-induced migration trends were consistent with reported invasive potentials of implanted gliomas. The models developed for this study imply that flow-modulated motility involves mechanotransduction of fluid shear stress affecting MMP activation and expression. These models should be useful for the continued study of interstitial flow effects on processes that affect tumor progression.

Show MeSH
Related in: MedlinePlus