Real time electronic cell sensing systems 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 system for monitoring cell-substrate impedance, comprising:
a) one or more multiple well cell-substrate impedance monitoring devices, wherein at least two of the multiple wells of said device comprise an electrode array at the bottom of the well, wherein said electrode array is individually addressed, further wherein said device can be used to measure differences in impedance values that relate to cell behavior;
b) an impedance analyzer;
c) a device station comprising electronic circuitry that can engage said device and selectively connect said two or more electrode arrays of said device to said impedance analyzer; and
d) a software program that can control said device station and record and analyze data obtained from said impedance analyzer;
wherein said electrode array has an approximately uniform electrode resistance distribution across said electrode array so that the electrode resistances between two locations on said array do not differ by more than 30%.
2. The system of claim 1 , wherein said device station comprises electronic switches that can switch on and off connections of each of said two or more electrode arrays to said impedance analyzer.
3. The system of claim 1 , wherein said software program can direct said device station to measure impedance values at regular or irregular time intervals from one or more of said two or more electrode arrays.
4. The system of claim 1 , wherein said impedance analyzer can measure impedance at one or more frequencies.
5. The system of claim 1 , wherein said software program can store said data.
6. The system of claim 1 wherein said system can display said data.
7. The system of claim 1 , wherein said software can calculate a cell index for one or more time points for one or more wells of said multi-well plate based on impedance values measured from said one or more electrode arrays localized to said one or more wells.
8. The system of claim 6 wherein said system can display said cell index for said one or more time points data for said one or more wells.
9. The system of claim 1 , wherein said software is programmable to direct impedance monitoring of any of said two or more electrode arrays at chosen time intervals.
10. The system of claim 5 , wherein said software allows entry and display of experimental parameters.
11. A method of performing an assay that monitors cell-substrate impedance, comprising:
providing the system of claim 1 ;
introducing cells into at least one well of said system;
monitoring cell-substrate impedance of said at least one well.
12. The method of claim 11 , wherein said monitoring comprises analyzing impedance changes at three or more time points.
13. The method of claim 12 , wherein at least three of said three or more time points are spaced at regular intervals.
14. A method of performing an assay that monitors cell-substrate impedance in response to one or more test compounds, comprising:
providing the system of claim 1 ;
introducing cells into one or more wells of said system that comprise electrode arrays;
adding at least one test compound to said one or more wells; and
monitoring cell-substrate impedance of said one or more wells before and after adding said at least one test compound.
15. The method of claim 14 , wherein impedance is monitored at three or more time points.
16. The method of claim 14 , further comprising analyzing impedance values before and after adding said at least one test compound.
17. The method of claim 14 , further comprising introducing cells to at least one well to which a test compound is not added to create a control well.
18. The method of claim 16 , wherein said analyzing comprises calculating a cell index.
19. The method of claim 16 , wherein said analyzing can provide information on 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.
20. The method of claim 18 , wherein said cell index is used as an indicator of cytotoxicity.
21. A method for monitoring changes in cell-substrate impedance in response to IgE stimulation, comprising:
providing a system of claim 1 ;
introducing cells into one or more wells of said system, wherein each of said one or more wells comprises an electrode array;
adding IgE to said one or more wells of said system;
adding an antigen to said one or more wells of said system; and
monitoring cell-substrate impedance of at least one of said one or more wells of said system.
22. The method of claim 21 , wherein said cells are mast cells, eosinophils, basophils, or genetically engineered cells.
23. The method of claim 22 , wherein said cells are mast cells.
24. The system of claim 1 , wherein said electrode array is electrically connected to two connection pads.
25. The system of claim 1 , wherein said electrode resistances between said two locations on said array do not differ by more than 15%.
26. The system of claim 1 , wherein said electrode resistances between said two locations on said array do not differ by more than 5%.
27. The system of claim 1 , wherein said electrode resistances between said two locations on said array do not differ by more than 3%.