a biaxial cell stretcher client: frank yin, md. ph.d group 30 joshua leibowitz krista vedvik...
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A Biaxial Cell StretcherClient: Frank Yin, MD. Ph.D
Group 30Joshua LeibowitzKrista VedvikChristopher Zarins
Background
• Cells in the body experience mechanical forces• Heart• Lungs• Blood vessels
• Laboratory cell cultures should recreate physiological conditions
Need for a Cell Stretcher
• Studying the effects of mechanical force on aortic endothelial cells• Orientation and organization of cells
depends on stretching• Controlling deformation in both directions
gives the most accurate results
Other Uses of Stretching
•Cardiac—Induce alignment of stem cell derived cardiomyocytes (Tulloch, 2011)•Vascular—Study formation of
aneurysms (Ventikos, 2010)•Respiratory—Study the effects of
protein secretion (Arnold, 2006)
Need for Biaxial Tests
•Most current cell stretching experiments are uniaxial•Limits the validity of results
Scope
Design a device capable of applying 40% strain in two directions• Withstands incubator conditions (37˚C, 100%
humidity)• Maintains calibration over a period of weeks• Easy access to medium to allow for additions and
changes
Current approaches
•Culture on an elastic membrane (Patten, 2005)
•Culture imbedded in a pliable gel (Zile, 2006)
Cell culture
Elastic membraneAdhesion Protein
FlexCell system
•Uses pressure to deform a circular membrane•Applies radial
strain
Calculations
Taking E = 10 kPa, A0 = 1 cm2, L0 = 10 cm, ΔL = 4 cm,
F = 4 N
Required deflection force:
Motor accuracy:Assuming 1.8˚ stepper motor resolution, drive mechanism must have at least 0.2 mm deflection per degree
Design Schedule
Task/Milestone 3-Sep 10-Sep 17-Sep 24-Sep 1-Oct 8-Oct 15-Oct 22-Oct 29-Oct 5-Nov 12-Nov 19-Nov 26-Nov 3-Dec 10-DecProject Initiation
Project Selection
*Project Scope
Develop Project Plan
Develop Requirements
*Preliminary Oral Report
*Preliminary Written Report
*Web Page
Initial Risk Analysis
Design & Design Analysis
Feasibility Report
*Progress Oral Reports
*Progress Written Reports
*Final Oral Report
*Final Written Report
Project Poster Judging
Member Responsibilities Chris Josh Krista
Conceptualization
x x x
Device Components
Substrate x
Drive Mechanism x
Controller Interface x
Incubator Compatibility x
Imaging Compatibility x
Calibration x
Risk Analysis
x x x
Research
Feasibility x x x
Literature Searches x
Mathematical Parameters x
Prices/Quotes x
Reports
Initializing x
Scheduling/Labor Division x
Figures x
Copy-editing x
Presentations
Preliminary x
Progress x
Final x
Client Interactions
x x
Intellectual Property
x
Website
x
References• Arnold, S. P. et. al. Design of a New Stretching Apparatus and the
Effects of Cyclic Strain and Substratum on Mouse Lung Epithelial-12 Cells. Ann Biomed Eng, 2007 35, 1156-1164
• Paten, J.A. et. al. Design and Performance of an Optically Accessible, Low-Volume, Mechanobioreactor for Long-Term Study of Living Constructs. Tis Eng, 2011 17 Part C
• Tulloch, NL. et al. Growth of engineered human myocardium with mechanical loading and vascular coculture. Circ Res. 2011 Jun 4;109(1):47-59
• Ventikos et al. Modelling evolution and the evolving mechanical environment of saccular cerebral aneurysms. Biomech Model Mechanobiol 2011 10:109-132
• Zile MR. et al. Gel stretch method: A new method to measure constitutive properties of cardiac muscle cells. Am J Physiol. 1998 Jun;274(6 Pt 2):h2188-202
Questions?