2 research outputs found
Automated, Multiplexed Electrical Impedance Spectroscopy Platform for Continuous Monitoring of Microtissue Spheroids
Microtissue
spheroids in microfluidic devices are increasingly
used to establish novel in vitro organ models of the human body. As
the spheroids are comparably sizable, it is difficult to monitor larger
numbers of them by optical means. Therefore, electrical impedance
spectroscopy (EIS) emerges as a viable alternative to probing spheroid
properties. Current spheroid EIS systems are, however, not suitable
for investigating multiple spheroids in parallel over extended time
in an automated fashion. Here we address this issue by presenting
an automated, multiplexed EIS (AMEIS) platform for impedance analysis
in a microfluidic setting. The system was used to continuously monitor
the effect of the anticancer drug fluorouracil (5-FU) on HCT116 cancer
spheroids. Simultaneous EIS monitoring of up to 15 spheroids was performed
in parallel over 4 days at a temporal resolution of 2 min without
any need for pumps. The measurements were continuous in nature, and
the setup was kept in a standard incubator under controlled conditions
during the measurements. A baseline normalization method to improve
robustness and to reduce the influence of slow changes in the medium
conductivity on the spheroid EIS readings has been developed and validated
by experiments and means of a finite-element model. The same method
and platform was then used for online monitoring of cardiac spheroids.
The beating frequency of each cardiac spheroid could be read out in
a completely automated fashion. The developed system constitutes a
promising method for simultaneously evaluating drug impact and/or
toxic effects on multiple microtissue spheroids
Electrical Impedance Spectroscopy for Microtissue Spheroid Analysis in Hanging-Drop Networks
Electrical
impedance spectroscopy (EIS) as a label-free and noninvasive
analysis method receives growing attention for monitoring three-dimensional
tissue constructs. In this Article, we present the integration of
an EIS readout function into the hanging-drop network platform, which
has been designed for culturing microtissue spheroids in perfused
multitissue configurations. Two pairs of microelectrodes have been
implemented directly in the support of the hanging drops by using
a small glass inlay inserted in the microfluidic structure. The pair
of bigger electrodes is sensitive to the drop size and allows for
drop size control over time. The pair of smaller electrodes is capable
of monitoring, on the one hand, the size of microtissue spheroids
to follow, for example, the growth of cancer microtissues, and, on
the other hand, the beating of cardiac microtissues in situ. The presented
results demonstrate the feasibility of an EIS readout within the framework
of multifunctional hanging-drop networks