8.26.16 Journal Club Presentaiton
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Transcript of 8.26.16 Journal Club Presentaiton
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Liver injury-on-a-chip
Soon Sung HongCEM Laboratory
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BBC News
Pentagon plans cyber-insect armyBy Gary Kitchener Last Updated: Thursday, 16 March 2006, 15:01 GMT
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BioMEMS (Bio-Micro-Electro-Mechanical-Systems)
Biology Microfabrication & Microfluidics
Bioapplications
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Introduction• Liver fibrosis
• Caused by exposure to toxicants, such as alcohol
• Aberrant deposition of extracellular matrix to form scar tissue
• Loss of hepatic function
• Transforming growth factor (TGF)-B• Key fibrogenic cytokine
• Associated with activation of stellate cells by hepatic TGF-B
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Traditional Techniques
Conditioned media Transwell Co-culture
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Problem• Difficult to monitor paracrine interactions using traditional culture
techniques (ie. Conditioned media and transwell co-cultures)
• Unable to replicate the high local concentrations of secreted signals present in vivo
• Secreted molecules diluted rapidly in the large volume of media
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Hypothesis
“Close proximity of the two cell types in the microfluidic co-culture system may better recapitulate local concentrations of signaling molecules produced during liver injury”
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Co-cultivated Microfluidic Device
Cell-culture chamber: 10 mm x 1 mm x 0.1mm
Sensing Chamber: 10mm x 0.2mm x 0.1mm
Glass plate
PDMS: flow layer
Actuation layer
Cell-culture chamber: 8 mm x 1.8 mm x 0.075mm
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Real Device Fabrication
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Experiments MethodConditioned Media Transwell Plate Microfluidic Device
ethanol
Step 1 Hepatocytes induced with alcohol for 48 hours
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Experiments MethodConditioned Media Transwell Plate Microfluidic Device
stellate cells treated with conditioned
media from injured hepatocytes
stellate cells on top of a transwell insert
introduced to well with injured hepatocytes
the wall was raised to start cell communication
ethanol
Step 1
Step 2
Hepatocytes induced with alcohol for 48 hours
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Figure 1
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Shortcomings
“The role of hepatic TGF-B on stellate cell activation is not shown directly”
“Difficult to characterize dynamics of reciprocal signaling using molecular biology approaches”
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Microfluidic Device with Integrated Biosensors• For better understanding of the dynamics behind TGF-B secretion• Aptamer-based biosensors integrated • Sensing chambers with gold electrodes implemented
Figure 4
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BiosensorsFigure 5
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Monoculture ExperimentFigure 6
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Hypothesis
“ injured hepatocytes send TGF-B molecules to activate neighboring stellate cells”
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ResultsFigure 7
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Conclusion
• The importance of hepatocytes as early inducers of liver injury• Alcohol injures the cells that can metabolize it – the hepatocytes- who
in turn send injury signals to neighboring stellate cells
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Overall Quality
• Straightforward• Leads to the conclusion in a succinct manner • Doesn’t include the controls and other comparable data • Lacks consistency in terms of experimental materials
• Rat hepatocytes and human stellate cells used• Immortalized human stellate cell line and primary rat hepatocytes• Dimensions of the two types of microfluidic device are different • Difference in levels between the media chamber • Difference in the volume of media that they use between the 3 models
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Pg. 4469
Rat hepatocytes and human stellate cells used
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Co-cultivated Microfluidic Device
Cell-culture chamber: 10 mm x 1 mm x 0.1mm
Sensing Chamber: 10mm x 0.2mm x 0.1mm
Glass plate
PDMS: flow layer
Actuation layer
Cell-culture chamber: 8 mm x 1.8 mm x 0.075mm
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Real Device Fabrication