The feasibility of using electrical impedance measurements for monitoring vascularization in 3D cell cultures
Hailla, Sonja (2022)
Hailla, Sonja
2022
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2023-01-18
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202212309852
https://urn.fi/URN:NBN:fi:tuni-202212309852
Tiivistelmä
Compared to 2D cell cultures, 3D cell cultures are more accurately able to imitate the structures and functions of living tissues. Thus, their use in research is becoming more prevalent. As a result, there is also a need for methods that can be used to reliably monitor these cell cultures. Currently, the gold standard is optical imaging, which is an effective tool but requires use of labels, is usually time-consuming, labour-intensive and often also destructive in the case of thick 3D samples. Electrical impedance spectroscopy (EIS) could provide a non-invasive, label-free, less time-consuming and possibly even continuous way of monitoring cell cultures.
The aim of this thesis was to assess the feasibility of using electrical impedance measurements for specifically monitoring the development of vascular networks in 3D cell cultures. The work in this thesis was divided into two parts: performing EIS measurements and modelling electrical impedance measurements. The EIS measurements were performed once a day for eight consecutive days using an impedance spectroscope on cell cultures with a mixture of adipose stem/stromal cells (ASCs) and human umbilical vein endothelial cells (HUVECs) as well as reference samples.
The electrical impedance measurement modelling was performed using COMSOL Multiphysics. Modelling was used to assess how changes in a cell culture with a developing vascular network theoretically affect the measured impedance. This was done by modelling how changing the number of cells in the model and changing the vascular network in the model affect the simulated impedance. Additionally, the sensitivity fields of measurements with different electrode layouts and measurement configurations were assessed.
The EIS measurements did not consistently show a detectable change in the measured impedance as the vascular network developed in all cell samples. This could be because of the limited sensitivity in the sample region provided by the measurement set-up used because electrodes had to be placed further away from the sample region. Simulations however showed that moving the electrodes closer to the sample region helps in detecting changes in the sample. This change in electrode location resulted in significantly larger differences in measured impedance that could be used to detect vascular network development. When a vascular network was added into a model that previously had no vascular network, the change in the simulated impedance value was -5% when electrodes were in locations similar to those used in measurements, and -36% when electrodes were placed closer to the sample. Based on this, more research into this method is needed. EIS measurements could be repeated in the future with improved electrode placement and possibly using different types of cell cultures.
The aim of this thesis was to assess the feasibility of using electrical impedance measurements for specifically monitoring the development of vascular networks in 3D cell cultures. The work in this thesis was divided into two parts: performing EIS measurements and modelling electrical impedance measurements. The EIS measurements were performed once a day for eight consecutive days using an impedance spectroscope on cell cultures with a mixture of adipose stem/stromal cells (ASCs) and human umbilical vein endothelial cells (HUVECs) as well as reference samples.
The electrical impedance measurement modelling was performed using COMSOL Multiphysics. Modelling was used to assess how changes in a cell culture with a developing vascular network theoretically affect the measured impedance. This was done by modelling how changing the number of cells in the model and changing the vascular network in the model affect the simulated impedance. Additionally, the sensitivity fields of measurements with different electrode layouts and measurement configurations were assessed.
The EIS measurements did not consistently show a detectable change in the measured impedance as the vascular network developed in all cell samples. This could be because of the limited sensitivity in the sample region provided by the measurement set-up used because electrodes had to be placed further away from the sample region. Simulations however showed that moving the electrodes closer to the sample region helps in detecting changes in the sample. This change in electrode location resulted in significantly larger differences in measured impedance that could be used to detect vascular network development. When a vascular network was added into a model that previously had no vascular network, the change in the simulated impedance value was -5% when electrodes were in locations similar to those used in measurements, and -36% when electrodes were placed closer to the sample. Based on this, more research into this method is needed. EIS measurements could be repeated in the future with improved electrode placement and possibly using different types of cell cultures.