Impedance measurement system for embryonic stem cell and embryoid body cultures
Montgomery, Sarah Lynn
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The objective of the proposed research is to design an experimental setup to assess the ability of impedance measurements to characterize mouse embryonic stem cell (ESC) and embryoid body (EB) growth and differentiation. Existing quality assurance measurements used to stage the growth and differentiation of embryoid bodies are labor intensive and most often destructive to the cells, thus present methods are typically valid for a single time point. Bioimpedance measurements are non-invasive and non-destructive, presenting an alternative approach to this challenge. These measurements can be done continuously for real-time measurements on the changes in embryoid body growth and differentiation. A system capable of making bioimpedance measurements of ESC and EB suspensions was designed along with a biocompatible test device to hold the cells and Ag-AgCl electrodes. The system uses a lock-in amplifier to record the magnitude and phase changes of the ESC and EB suspensions when a 1 Vpp signal sweeping frequencies from 100 Hz to 100 kHz is applied. The system performance was validated with a test case of 1 mL of 0.1 M KCl. Then experiments with cell culture media, ESCs, and EBs were performed, with varying concentrations of cells and EBs. Experimental results for single ESC suspensions showed promise in detecting a difference in cell concentration between 2 million and 4 million cells in 0.5 mL of media. Results for four day old EBs were ambiguous, and we conclude that a different experimental set up is required due to EB settling during experimentation.