Real time electronic cell sensing system and applications for cell-based assays
The present invention includes devices, systems, and methods for assaying cells using cell-substrate impedance monitoring. In one aspect, the invention provides cell-substrate impedance monitoring devices that comprise electrode arrays on a nonconducting substrate, in which each of the arrays has an approximately uniform electrode resistance across the entire array. In another aspect, the invention provides cell-substrate monitoring systems comprising one or more cell-substrate monitoring devices comprising multiple wells each having an electrode array, an impedance analyzer, a device station that connects arrays of individual wells to the impedance analyzer, and software for controlling the device station and impedance analyzer. In another aspect, the invention provides cellular assays that use impedance monitoring to detect changes in cell behavior or state. In some preferred aspects, the assays are designed to investigate the affects of compounds on cells, such as cytotoxicity assays. In other preferred aspects, the assays are designed to investigate the compounds that effect IgE-mediated responses of cells to antigens.
1. A method of performing a cell-based assay that monitors cell-substrate impedance in response to one or more test compounds, comprising:
(a) providing a cell-substrate impedance monitoring system, comprising:
(i) at least one multiple-well cell-substrate impedance measuring device, wherein at least two of the multiple wells comprise an electrode array at the bottom of the well, wherein each electrode array comprises two electrode structures and each electrode structure comprises multiple electrode elements, further wherein each electrode array is individually addressed;
(ii) an impedance analyzer;
(iii) a device station comprising electronic circuitry capable of engaging said device and selecting and connecting electrode arrays within any of the multiple wells to the impedance analyzer;
(iv) a software program capable of controlling the device station and performing data acquisition and data analysis from said impedance analyzer;
(b) introducing cells into one or more wells of said system that comprise electrode arrays;
(c) adding at least one test compound to said one or more wells;
(d) monitoring cell-substrate impedance of said one or more wells before and after adding said at least one test compound; and
(e) analyzing impedance values and calculating cell index values before and after adding said at least one test compound and providing information about cell responses to said at least one test compound.
2. The method according to claim 1 , wherein impedance is monitored at three or more time points.
3. The method according to claim 1 , further comprising introducing cells to at least one well to which the test compound is not added to create a control well.
4. The method according to claim 1 , wherein said cell index values are compared.
5. The method according to claim 1 , wherein said cell index values are used as an indicator of cytotoxicity.
6. The method according to claim 1 , wherein said analyzing further comprises providing information selected from the group consisting of cell proliferation, cell death, cell adhesion, cell apoptosis, cell differentiation, cell survival, cytotoxicity, cell morphology, cell quantity, cell quality, time-dependent cytotoxicity of a compound, IgE-mediated cell activation or stimulation, receptor-ligand binding, viral and bacterial toxin mediated cell pathologic changes, presence and quantity of neutralizing antibodies, specific T-cell mediated cytotoxic effects, presence and affinity of ligand-receptor binding.
7. The method of claim 1 , wherein said analyzing further comprises providing information selected from the group consisting of cell attachment or adhesion status on the substrate including on the electrodes, the degree of cell spreading, the attachment area of a cell, the degree of tightness of cell attachment, cell morphology, cell growth or proliferation status, number of viable cells and/or dead cells in the well, cytoskeleton change and re-organization and number of cells going through apoptosis and/or necrosis.
8. The method of claim 7 , wherein said analyzing provides information about cell morphology, wherein said test compound binds to a receptor on the cell surface and said binding leads to a change in cell morphology.
9. The method according to claim 1 , wherein cells are added to at least two wells of said device, each of which comprises an electrode array, and wherein impedance is monitored from at least two wells that comprise cells and an electrode array.
10. The method according to claim 1 , wherein said monitoring impedance comprises monitoring impedances at three or more time points spaced at regular intervals.
11. The method according to claim 1 , wherein said cells are primary cells isolated from a species or cells obtained from cell lines.
12. The method according to claim 1 , wherein impedance is monitored at one frequency.
13. The method according to claim 1 , wherein impedance is monitored at multiple frequencies.
14. The method according to claim 13 , wherein impedance is monitored at multiple frequencies at a time point.