8.26.16 journal club presentaiton
TRANSCRIPT
Liver injury-on-a-chip
Soon Sung HongCEM Laboratory
BBC News
Pentagon plans cyber-insect armyBy Gary Kitchener Last Updated: Thursday, 16 March 2006, 15:01 GMT
BioMEMS (Bio-Micro-Electro-Mechanical-Systems)
Biology Microfabrication & Microfluidics
Bioapplications
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
Traditional Techniques
Conditioned media Transwell Co-culture
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
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”
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
Real Device Fabrication
Experiments MethodConditioned Media Transwell Plate Microfluidic Device
ethanol
Step 1 Hepatocytes induced with alcohol for 48 hours
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
Figure 1
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”
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
BiosensorsFigure 5
Monoculture ExperimentFigure 6
Hypothesis
“ injured hepatocytes send TGF-B molecules to activate neighboring stellate cells”
ResultsFigure 7
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
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
Pg. 4469
Rat hepatocytes and human stellate cells used
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
Real Device Fabrication