title: Liver injury-on-a-chip: microfluidic co-cultures with integrated biosensors for monitoring liver cell signaling during injury.
abstract: Tissue injury triggers complex communication between cells via secreted signaling molecules such as cytokines and growth factors. Discerning when and where these signals begin and how they propagate over time is very challenging with existing cell culture and analysis tools. The goal of this study was to develop new tools in the form of microfluidic co-cultures with integrated biosensors for local and continuous monitoring of secreted signals. Specifically, we focused on how alcohol injury affects TGF-β signaling between two liver cell types, hepatocytes and stellate cells. Activation of stellate cells happens early during liver injury and is at the center of liver fibrosis. We demonstrated that alcohol injury to microfluidic co-cultures caused significantly higher levels of stellate cell activation compared to conditioned media and transwell injury experiments. This highlighted the advantage of the microfluidic co-culture: placement of two cell types in close proximity to ensure high local concentrations of injury-promoting secreted signals. Next, we developed a microsystem consisting of five chambers, two for co-culturing hepatocytes with stellate cells and three additional chambers containing miniature aptamer-modified electrodes for monitoring secreted TGF-β. Importantly, the walls separating microfluidic chambers were actuatable; they could be raised or lowered to create different configurations of the device. The use of reconfigurable microfluidics and miniature biosensors revealed that alcohol injury causes hepatocytes to secrete TGF-β molecules, which diffuse over to neighboring stellate cells and trigger production of additional TGF-β from stellate cells. Our results lend credence to the emerging view of hepatocytes as active participants of liver injury. Broadly speaking, our microsystem makes it possible to monitor paracrine crosstalk between two cell types communicating via the same signaling molecule (e.g. TGF-β).
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, 451 Health Sciences, Davis, CA, USA. arevzin@ucdavis.edu.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, 451 Health Sciences, Davis, CA, USA. arevzin@ucdavis.edu.
authors.forename: Dipali
authors.initials: D
authors.lastname: Patel
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, 451 Health Sciences, Davis, CA, USA. arevzin@ucdavis.edu.
authors.forename: Timothy
authors.initials: T
authors.lastname: Kwa
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, 451 Health Sciences, Davis, CA, USA. arevzin@ucdavis.edu.
authors.forename: Amranul
authors.initials: A
authors.lastname: Haque
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, 451 Health Sciences, Davis, CA, USA. arevzin@ucdavis.edu.
authors.forename: Zimple
authors.initials: Z
authors.lastname: Matharu
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, 451 Health Sciences, Davis, CA, USA. arevzin@ucdavis.edu.
authors.forename: Gulnaz
authors.initials: G
authors.lastname: Stybayeva
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, 451 Health Sciences, Davis, CA, USA. arevzin@ucdavis.edu.
authors.forename: Yandong
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Division of Gastroenterology, Department of Medicine, Duke University, 595 LaSalle Street, Snyderman Building, Suite 1073, Durham, NC, USA.
authors.forename: Anna Mae
authors.initials: AM
authors.lastname: Diehl
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, 451 Health Sciences, Davis, CA, USA. arevzin@ucdavis.edu.
authors.forename: Alexander
authors.initials: A
authors.lastname: Revzin
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D002460:Cell Line; D018920:Coculture Techniques / Q000295:instrumentation*; D000431:Ethanol / Q000494:pharmacology; D020342:Finite Element Analysis; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D056656:Lab-On-A-Chip Devices; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000293:injuries*; D015398:Signal Transduction; D018511:Systems Integration; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
chemical_list: D053773:Transforming Growth Factor beta1; D000431:Ethanol