Monitoring glucose consumption of cells towards In-line monitoring on Organ-on-a-Chip as a more reliable toxicological assessment of chemical entities

• 8:55 - 9:20, September 23 (Wednesday)
• Speaker: Tomoharu Osada
• The micro-physiological system (MPS) is expected to be a practical drug developmental tool for assessing efficacy and safety of chemical entities. MPS is also operated under appropriate protocols to ensure the integrity of experimental outcomes. To meet those demands, non-invasive monitoring of culture conditions on the MPS is supposed to be useful. Glucose, which is finally metabolized into lactate, is one of the fundamental energy sources of the cells. Drug-responsiveness of cells may be variable depending on the glucose consumption status of the culture conditions. First, we collected fundamental experimental data of glucose consumption behavior in the culture medium with HEPG2 cells with senor chips tested in this study to detect concentration of both glucose and lactate in less than 1 µL of each sample volume. Glucose concentration decreased in the longer culture period, with more numbers of cultured cells, and with less volume of culture medium. On the other hand, lactate concentration was vice vase. Second, cell proliferation is suppressed when doxorubicin (DOX) is exposed to the cells, accompanying lower glucose consumption in the DOX-exposed cells. These observations indicate that glucose consumption is related to physiology and drug responsiveness of cultured cells, suggesting the integrity of microenvironment of the cultured cells on MPS. Consequently, our findings will offer a rationale for in-line monitoring on MPS for a better understanding of the physiology of the cells cultured on MPS. Incidentally, it is also applicable to define the optimal culture conditions used for co-culture on MPS.

Effect of Age on the Repeated-Dose Liver Micronucleus Assay Using 2,4-Dinitrotoluene

• 18:30 - 19:30, September 8 (Tuesday)
• Presenter: Miyuki Shigano
• The repeated-dose liver micronucleus (RDLMN) assay is being developed toward an IWGT-recommended protocol and potential OECD guideline adoption. During this process, the potential impact of animal age and the applicability to animals starting dosing at 8 weeks of age have been identified as key issues, particularly for integration into repeated-dose toxicity studies. To address these questions, the IWGT Liver MN subgroup selected compounds showing weak positive responses at 6-week-start dosing.
  
  In the present study, we evaluated 2,4-dinitrotoluene (2,4-DNT), one of the representative weak-positive compounds, to compare RDLMN responses in rats aged 6 or 8 weeks at the start of administration. 2,4-DNT induced liver micronuclei in both age groups, with comparable responses between age groups, indicating no clear age-related impact. These findings, obtained with a weakly positive compound, support the applicability of the RDLMN assay to animals starting dosing at 8 weeks of age and its integration into repeated-dose toxicity studies.