title: Noninvasively measuring respiratory activity of rat primary hepatocyte spheroids by scanning electrochemical microscopy.
abstract: Construction of an in vitro drug screening method for evaluating drug metabolism and toxicity by using cells is required instead of the conventional in vivo one that uses animals. In order to realize the in vitro study, analyzing the cellular activity or viability noninvasively in advance of the screening is essential. The aim of the current study is to establish a method that can evaluate the cellular activity depending on spheroid sizes by means of oxygen consumption and to determine the valid diameter of hepatocyte spheroids. To measure the respiratory activity of the spheroids, which were formed on a nanopillar sheet, we applied scanning electrochemical microscopy (SECM). From the viewpoint of high respiratory activity and its small variation, we determined that spheroids with 70 μm in diameter were adequate. We then performed a gene expression analysis by using a real-time PCR to evaluate the correlation with respiratory activity. As a result, a higher expression level of Hnf4α, which is essential for hepatocytes to fulfill many liver functions and is the indicator of well-differentiated hepatocytes, showed relatively higher respiratory activity. We concluded that the noninvasive SECM technique could evaluate the cellular activity of a single spheroid. Noninvasively measuring cellular activity by SECM makes it possible to evaluate the cellular activity prior to a nonclinical test and enables the continued monitoring of the drug response by using single spheroid. SECM becomes a powerful tool to satisfying the increasing demand for an in vitro system in the course of new drug development.
authors.affiliation: Central Research Laboratory, Hitachi Ltd., Hatoyama, Saitama 350-0395, Japan. Electronic address: ryosuke.takahashi.jr@hitachi.com.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Takahashi
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, Aramaki-Aoba 6-6-11, Sendai 980-8579, Japan.
authors.forename: Yuanshu
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, Aramaki-Aoba 6-6-11, Sendai 980-8579, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Horiguchi
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, Aramaki-Aoba 6-6-11, Sendai 980-8579, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shiku
authors.affiliation: Central Research Laboratory, Hitachi Ltd., Hatoyama, Saitama 350-0395, Japan; Social Innovation Business Project Div., Hitachi Ltd., Sotokanda, Chiyoda, Tokyo 101-8608, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sonoda
authors.affiliation: Central Research Laboratory, Hitachi Ltd., Higashi-koigakubo, Kokubunji, Tokyo 185-8601, Japan.
authors.forename: Naoshi
authors.initials: N
authors.lastname: Itabashi
authors.affiliation: Central Research Laboratory, Hitachi Ltd., Higashi-koigakubo, Kokubunji, Tokyo 185-8601, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Yamamoto
authors.affiliation: Social Innovation Business Project Div., Hitachi Ltd., Sotokanda, Chiyoda, Tokyo 101-8608, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Saito
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, Aramaki-Aoba 6-6-11, Sendai 980-8579, Japan; WPI Advanced Institute for Materials Research, Tohoku University, Kitahara 2-2-1, Sendai 980-8577, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Matsue
authors.affiliation: Central Research Laboratory, Hitachi Ltd., Hatoyama, Saitama 350-0395, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Hisada
mesh_terms: D000465:Algorithms; D000818:Animals; D002468:Cell Physiological Phenomena; D019069:Cell Respiration; D002478:Cells, Cultured; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics; D022781:Hepatocytes / Q000166:cytology*; D008297:Male; D064347:Microscopy, Electrochemical, Scanning; D049329:Nanostructures / Q000737:chemistry*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011916:Rats, Inbred F344; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018874:Spheroids, Cellular / Q000166:cytology*
chemical_list: D051557:Hepatocyte Nuclear Factor 4; C496594:Hnf4a protein, rat; D012333:RNA, Messenger
keywords: Nanopillar sheet; Real-time PCR; Scanning electrochemical microscopy; Spheroid