title: Impedimetric quantification of the formation process and the chemosensitivity of cancer cell colonies suspended in 3D environment.
abstract: In cancer research, colony formation assay is a gold standard for the investigation of the development of early tumors and the effects of cytotoxic agents on tumors in vitro. Quantification of cancer cell colonies suspended in hydrogel is currently achieved by manual counting under microscope. It is challenging to microscopically quantify the colony number and size without subjective bias. In this work, impedimetric quantification of cancer cell colonies suspended in hydrogel was successfully developed and provides a quantitative and objective method to describe the colony formation process and the development of colony size during the culture course. A biosensor embedded with a pair of parallel plate electrodes was fabricated for the impedimetric quantification. Cancer cell (cell line: Huh-7) were encapsulated in methyl cellulose hydrogel and cultured to gradually form cancer cell colonies suspended in 3D environment. At pre-set schedule during the culture course, small volume (50 μL) of colonies/MC hydrogel was collected, mixed with measurement hydrogel, and loaded to the biosensor for measurement. Hence, the colony formation process could be quantitatively represented by a colony index and a colony size index calculated from electrical impedance. Based on these developments, chemosensitivity of cancer cell colonies under different concentrations of anti-cancer drug, i.e., doxorubicin, was quantitatively investigated to study the efficacy of anti-cancer drug. Also, dose-response curve was constructed to calculate the IC50 value, which is an important indicator for chemosensitivity assay. These results showed the impedimetric quantification is a promising technique for the colony formation assay.
authors.affiliation: Graduate Institute of Medical Mechatronics, Chang Gung University, Taiwan; Department of Mechanical Engineering, Chang Gung University, Taiwan. Electronic address: kflei@mail.cgu.edu.tw.
authors.forename: Kin Fong
authors.initials: KF
authors.lastname: Lei
authors.affiliation: Graduate Institute of Medical Mechatronics, Chang Gung University, Taiwan.
authors.forename: Zong-Ming
authors.initials: ZM
authors.lastname: Wu
authors.affiliation: Graduate Institute of Medical Mechatronics, Chang Gung University, Taiwan.
authors.forename: Chia-Hao
authors.initials: CH
authors.lastname: Huang
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage; D015374:Biosensing Techniques; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000008:administration & dosage; D004354:Drug Screening Assays, Antitumor; D017097:Electric Impedance; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D009369:Neoplasms / Q000188:drug therapy* / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000473:pathology*
chemical_list: D000970:Antineoplastic Agents; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D004317:Doxorubicin
keywords: Chemosensitivity; Colony formation assay; Impedimetric quantification