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Cell Biomechanics and Methods

Z. Huang, A. Pettes, and B. Pruitt

August 2, 2007

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Motivation

Balaban et al, 2001

Force generation vectors

Cardiac myocyte

• Understanding mechanical effects on cellular processes and events triggered by mechanical stimuli (mechanotransduction)

• Determining the exact nature of mechanotransduction in– cardiac myocytes – sense of touch– bone remodeling

• Stress environment– an important parameter in tissue

engineering

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Motivation

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Motivation Applied External Force

Mechano-sensitive Ion Channel

signaling cascade

change in protein synthesis or post-translational modifications

conformal changes in structural proteins

altered gene expression

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Motivation• Forces are transmitted through adhesion sites

attached to the cytoskeleton• Deformation causes the cells to react

– Apoptosis, cell-division, growth

• Applications– Sense of Touch

– Cancer growth

– Hypertension

– Bone remodeling

– Heart attack due to blood clots

– Regenerative medicine

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Biology Force Measurements

Technique Force Range Authors Year

Antibody-Antigen Binding 100 pN Lee and Colton 1994

Cellular Adhesion 5-100 pN Adams, Chen, Smith and Nelson

1998

Saif 2003

Actin-Myosin Mechanical Behavior

10 pN-10nN Finer, Simmons and Spudich

1994

Protein Folding 0.1-100 pN Powers, Daburesse, Noller

1993

Further research is necessary to develop more precise models of cellular behavior, drug development, testing, and manufacturing.

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Cell Patterning

AFM of NIH 3T3 Vinculin Plaques

K. Parkerfocal adhesions

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Cell Patterning

• Devices to apply controlled forces / strains to live cells and study the response

• Estimate the cell stiffness and monitor changes due to loading effects

• Correlate response with cytoskeleton dynamics and signaling molecules

• Dynamically measure effects of cyclic loading and varying strain rates

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Cell Patterning

Pattern a binding agent (e.g. Fibronectin) through soft lithography to confinecell movement and study isolated and/or patterned arrays of cells

Whitesides et al, 2001

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Available Measurement Techniques

Van Vliet, 2003

Cell PopulationsSD - Substrate Deformation

Cell Populations / Single CellsEPT - Embedded Particle Tracking MTC - Magnetic Twisting CytometrymPAD - microfabricated Post Array Detector

Single CellsCD – CytodetacherMA - Micropipette AspirationOS - Optical Stretcher

Single Cells / MoleculesAFM - Atomic Force MicroscopyBFP - Biomembrane Force ProbeHRFS – High Resolution Force SpectroscopyMN - MicroneedlesMT - Magnetic TweezerOT - Optical Trap

Force [N]

Distance [m]

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Forces in Single CellsCell Populations

SD - Substrate DeformationCell Populations / Single Cells

EPT - Embedded Particle Tracking MTC - Magnetic Twisting CytometrymPAD - Microfabricated Post Array Detector

Single CellsCD – CytodetacherMA - Micropipette AspirationOS - Optical Stretcher

Single Cells / MoleculesAFM - Atomic Force MicroscopyBFP - Biomembrane Force ProbeHRFS – High Resolution Force SpectroscopyMN - MicroneedlesMT - Magnetic TweezerOT - Optical Trap

Van Vliet, 2003

Force [N]

Distance [m]

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Micropatterned Substrates

mPAD

Tan et al., 2003 Beningo et al., 2003

EPT

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Micropost Array Studies

mPAD

Chen et al., 1997

mPAD

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Magnetic Twisting Cytometry (MTC)

Morales et al., 2001

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Properties of Cellular and Sub-cellular Components

Cell PopulationsSD - Substrate Deformation

Cell Populations / Single CellsEPT - Embedded Particle Tracking MTC - Magnetic Twisting CytometrymPAD - microfabricated Post Array Detector

Single CellsCD – CytodetacherMA - Micropipette AspirationOS - Optical Stretcher

Single Cells / MoleculesAFM - Atomic Force MicroscopyBFP - Biomembrane Force ProbeHRFS – High Resolution Force Spectroscopy MN - MicroneedlesMT - Magnetic TweezerOT - Optical Trap

Van Vliet et al., 2003

Force [N]

Distance [m]

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Micropipette Aspiration (MA)

Jones et al., 1999

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Atomic Force Microscopy (AFM)

Van Vliet et al., 2003

AFM

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Optical Trapping (OT)

Dao et al., 2003

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Stimuli and Response in Cell PopulationsCell Populations

SD - Substrate DeformationCell Populations / Single Cells

EPT - Embedded Particle Tracking MTC - Magnetic Twisting CytometrymPAD - microfabricated Post Array Detector

Single CellsCD – CytodetacherMA - Micropipette AspirationOS - Optical Stretcher

Single Cells / MoleculesAFM - Atomic Force MicroscopyBFP - Biomembrane Force ProbeHRFS – High Resolution Force Spectroscopy MN - MicroneedlesMT - Magnetic TweezerOT - Optical Trap

Other TechniquesDeformable SubstratesFlow Shear Stress

Van Vliet et al., 2003

Force [N]

Distance [m]

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Stimuli and Response in Cell Populations

Deformable Substrates

Feeback and Clarke, 2000

Usami et al., 1993

Flow Shear Stress

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MEMS Cell-Force Measurments

Nelson et al, 2005

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MEMS Cell-Force Measurments

Nelson et al, 2005

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MEMS Heart Cell-Force Transducer

Lin et al., 2000

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Cell-Force Measurements in Malaria-affected Cells

Healthy red blood cell

↓Exposed to P. ↓falciparum parasite

Uninfected

Ring stage

Trophozoite stage

Schizont stage

Suresh et al., 2005

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Thank you