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Open access to novel dual flow chamber technology for in vitro cell mechanotransduction, toxicity and pharamacokinetic studies.

Anderson EJ, Knothe Tate ML - Biomed Eng Online (2007)

Bottom Line: Bench-top testing of the novel chamber prototype shows improvements, in the ease of use as well as in performance, compared to the other commercial chambers.The predictability of the imparted stress improves both experiment repeatability as well as the accuracy of inter-study comparisons.Carefully controlling the stresses on cells is critical in effectively mimicking in vivo situations.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical & Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA. eric.anderson@case.edu

ABSTRACT

Background: A major stumbling block for researchers developing experimental models of mechanotransduction is the control of experimental variables, in particular the transmission of the mechanical forces at the cellular level. A previous evaluation of state of the art commercial perfusion chambers showed that flow regimes, applied to impart a defined mechanical stimulus to cells, are poorly controlled and that data from studies in which different chambers are utilized can not be compared, even if the target stress regimes are comparable.

Methods: This study provides a novel chamber design to provide both physiologically-based flow regimes, improvements in control of experimental variables, as well as ease of use compared to commercial chambers. This novel design achieves controlled stresses through five gasket designs and both single- and dual-flow regimes.

Results: The imparted shear stress within the gasket geometry is well controlled. Fifty percent of the entire area of the 10 x 21 mm universal gasket (Gasket I, designed to impart constant magnitude shear stresses in the center of the chamber where outcome measures are taken), is exposed to target stresses. In the 8 mm diameter circular area at the center of the chamber (where outcome measures are made), over 92% of the area is exposed to the target stress (+/- 2.5%). In addition, other gasket geometries provide specific gradients of stress that vary with distance from the chamber inlet. Bench-top testing of the novel chamber prototype shows improvements, in the ease of use as well as in performance, compared to the other commercial chambers. The design of the chamber eliminates flow deviations due to leakage and bubbles and allows actual flow profiles to better conform with those predicted in computational models.

Conclusion: The novel flow chamber design provides predictable and well defined mechanical forces at the surface of a cell monolayer, showing improvement over previously tested commercial chambers. The predictability of the imparted stress improves both experiment repeatability as well as the accuracy of inter-study comparisons. Carefully controlling the stresses on cells is critical in effectively mimicking in vivo situations. Overall, the improved perfusion flow chamber provides the needed resolution, standardization and in vitro model analogous to in vivo conditions to make the step towards greater use in research and the opportunity to enter the diagnostic and therapeutic market.

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Related in: MedlinePlus

Gasket IV shear stress plots. Wall shear stress for the three sampling locations, plotted from the chamber centerline to the wall. High gradients of shear stress are found near the entrance to the expansion zone (line 1), with nearly constant profiles near the midplane (lines 2, 3).
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Figure 14: Gasket IV shear stress plots. Wall shear stress for the three sampling locations, plotted from the chamber centerline to the wall. High gradients of shear stress are found near the entrance to the expansion zone (line 1), with nearly constant profiles near the midplane (lines 2, 3).

Mentions: The fourth gasket imposes the most abrupt widening and tapering geometry, where the resulting fluid regime parallels planar jet flow (Figure 13). The maximum velocity is found in the smaller sections of the gasket, near the inlet and outlet, where the magnitude dissipates within the widened flow area. Here, flow near the walls of the widened area has a velocity of nearly zero along the entire length of gasket. This profile causes an increased shear stress near the gasket centerline, with values decreasing with increasing distance from the center. At a location near the entrance to the widened area, the shear stress is nearly constant near the centerline, where a dramatic gradient is found roughly 1 mm from the center (Figure 14). As flow moves away from the entrance, the gradient in wall shear stress (from the center to walls) is decreased and a nearly constant stress is found at the midplane. This gasket geometry induces the largest change in stress between the widening entrance and the midplane, again providing unique and defined stress distributions.


Open access to novel dual flow chamber technology for in vitro cell mechanotransduction, toxicity and pharamacokinetic studies.

Anderson EJ, Knothe Tate ML - Biomed Eng Online (2007)

Gasket IV shear stress plots. Wall shear stress for the three sampling locations, plotted from the chamber centerline to the wall. High gradients of shear stress are found near the entrance to the expansion zone (line 1), with nearly constant profiles near the midplane (lines 2, 3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2235874&req=5

Figure 14: Gasket IV shear stress plots. Wall shear stress for the three sampling locations, plotted from the chamber centerline to the wall. High gradients of shear stress are found near the entrance to the expansion zone (line 1), with nearly constant profiles near the midplane (lines 2, 3).
Mentions: The fourth gasket imposes the most abrupt widening and tapering geometry, where the resulting fluid regime parallels planar jet flow (Figure 13). The maximum velocity is found in the smaller sections of the gasket, near the inlet and outlet, where the magnitude dissipates within the widened flow area. Here, flow near the walls of the widened area has a velocity of nearly zero along the entire length of gasket. This profile causes an increased shear stress near the gasket centerline, with values decreasing with increasing distance from the center. At a location near the entrance to the widened area, the shear stress is nearly constant near the centerline, where a dramatic gradient is found roughly 1 mm from the center (Figure 14). As flow moves away from the entrance, the gradient in wall shear stress (from the center to walls) is decreased and a nearly constant stress is found at the midplane. This gasket geometry induces the largest change in stress between the widening entrance and the midplane, again providing unique and defined stress distributions.

Bottom Line: Bench-top testing of the novel chamber prototype shows improvements, in the ease of use as well as in performance, compared to the other commercial chambers.The predictability of the imparted stress improves both experiment repeatability as well as the accuracy of inter-study comparisons.Carefully controlling the stresses on cells is critical in effectively mimicking in vivo situations.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical & Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA. eric.anderson@case.edu

ABSTRACT

Background: A major stumbling block for researchers developing experimental models of mechanotransduction is the control of experimental variables, in particular the transmission of the mechanical forces at the cellular level. A previous evaluation of state of the art commercial perfusion chambers showed that flow regimes, applied to impart a defined mechanical stimulus to cells, are poorly controlled and that data from studies in which different chambers are utilized can not be compared, even if the target stress regimes are comparable.

Methods: This study provides a novel chamber design to provide both physiologically-based flow regimes, improvements in control of experimental variables, as well as ease of use compared to commercial chambers. This novel design achieves controlled stresses through five gasket designs and both single- and dual-flow regimes.

Results: The imparted shear stress within the gasket geometry is well controlled. Fifty percent of the entire area of the 10 x 21 mm universal gasket (Gasket I, designed to impart constant magnitude shear stresses in the center of the chamber where outcome measures are taken), is exposed to target stresses. In the 8 mm diameter circular area at the center of the chamber (where outcome measures are made), over 92% of the area is exposed to the target stress (+/- 2.5%). In addition, other gasket geometries provide specific gradients of stress that vary with distance from the chamber inlet. Bench-top testing of the novel chamber prototype shows improvements, in the ease of use as well as in performance, compared to the other commercial chambers. The design of the chamber eliminates flow deviations due to leakage and bubbles and allows actual flow profiles to better conform with those predicted in computational models.

Conclusion: The novel flow chamber design provides predictable and well defined mechanical forces at the surface of a cell monolayer, showing improvement over previously tested commercial chambers. The predictability of the imparted stress improves both experiment repeatability as well as the accuracy of inter-study comparisons. Carefully controlling the stresses on cells is critical in effectively mimicking in vivo situations. Overall, the improved perfusion flow chamber provides the needed resolution, standardization and in vitro model analogous to in vivo conditions to make the step towards greater use in research and the opportunity to enter the diagnostic and therapeutic market.

Show MeSH
Related in: MedlinePlus