title: Digital microfluidics for automated hanging drop cell spheroid culture.
abstract: Cell spheroids are multicellular aggregates, grown in vitro, that mimic the three-dimensional morphology of physiological tissues. Although there are numerous benefits to using spheroids in cell-based assays, the adoption of spheroids in routine biomedical research has been limited, in part, by the tedious workflow associated with spheroid formation and analysis. Here we describe a digital microfluidic platform that has been developed to automate liquid-handling protocols for the formation, maintenance, and analysis of multicellular spheroids in hanging drop culture. We show that droplets of liquid can be added to and extracted from through-holes, or "wells," and fabricated in the bottom plate of a digital microfluidic device, enabling the formation and assaying of hanging drops. Using this digital microfluidic platform, spheroids of mouse mesenchymal stem cells were formed and maintained in situ for 72 h, exhibiting good viability (>90%) and size uniformity (% coefficient of variation <10% intraexperiment, <20% interexperiment). A proof-of-principle drug screen was performed on human colorectal adenocarcinoma spheroids to demonstrate the ability to recapitulate physiologically relevant phenomena such as insulin-induced drug resistance. With automatable and flexible liquid handling, and a wide range of in situ sample preparation and analysis capabilities, the digital microfluidic platform provides a viable tool for automating cell spheroid culture and analysis.
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, CA, USA.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Aijian
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, CA, USA Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA California NanoSystems Institute, University of California, Los Angeles, CA, USA garrell@chem.ucla.edu.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Garrell
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy*; D000818:Animals; D057205:Automation, Laboratory; D045744:Cell Line, Tumor; D002470:Cell Survival; D004351:Drug Resistance; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D006801:Humans; D056656:Lab-On-A-Chip Devices / Q000706:statistics & numerical data*; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D051379:Mice; D044085:Microfluidics / Q000379:methods*; D009924:Organ Culture Techniques; D018874:Spheroids, Cellular / Q000187:drug effects / Q000473:pathology*; D023822:Tissue Engineering / Q000379:methods
keywords: 3D cell culture; cell-based assays; digital microfluidics; electrowetting; spheroids