Using alternating electric fields to increase cell membrane permeability
Certain substances (e.g., large molecules) that ordinarily cannot traverse the cell membrane of cells can be introduced into cells by applying an alternating electric field to the cell for a period of time, wherein the frequency of the alternating electric field is selected so that application of the alternating electric field increases permeability of the cell membrane. Once the permeability of the cell membrane has been increased, the substance is able to cross the cell membrane. This approach is particularly useful in the context of cancer cells (e.g., glioblastoma).
1. An apparatus for treating a tumor in a subject's body and facilitating delivery of a substance across cell membranes in the subject's body, the apparatus comprising:
an AC voltage generator capable of operating at a first frequency between 50 and 500 kHz and a second frequency between 50 and 500 kHz, wherein the second frequency is different from the first frequency, the AC voltage generator having a control input, wherein the AC voltage generator is configured to output the first frequency when the control input is in a first state and to output the second frequency when the control input is in a second state; and
a controller programmed to (a) place the control input in the second state so that the AC voltage generator outputs the second frequency, (b) accept a request to switch to the first frequency, (c) upon receipt of the request, place the control input in the first state so that the AC voltage generator outputs the first frequency for an interval of time, and (d) when the interval of time has elapsed, automatically place the control input in the second state so that the AC voltage generator outputs the second frequency,
wherein the first frequency is selected to increase permeability of the cell membranes and the second frequency is selected to reduce viability of the cells in the tumor, and
wherein the interval of time is at least 12 hours.
2. The apparatus of claim 1 , further comprising:
a set of electrodes configured for affixation to the subject's body; and
wiring that connects an output of the AC voltage generator to the set of electrodes.
3. The apparatus of claim 1 , wherein the first frequency is between 250 kHz and 350 kHz, and the second frequency is between 150 kHz and 250 kHz.
4. The apparatus of claim 1 , wherein the first frequency is between 125 kHz and 175 kHz, and the second frequency is between 75 kHz and 125 kHz.
5. The apparatus of claim 1 , wherein the first frequency is between 75 kHz and 175 kHz, and the second frequency is between 100 kHz and 300 kHz.
6. The apparatus of claim 1 , wherein the controller is further programmed to, subsequent to the receipt of the request, switch the control input back and forth between the first state and the second state.
7. The apparatus of claim 1 , wherein the AC voltage generator is capable of operating at at least one additional frequency between 50 and 500 kHz, and wherein the AC voltage generator is configured to output the least one additional frequency when the control input is in at least one additional state, and
wherein the controller is programmed to cycle the control input through the second state and the at least one additional state prior to receipt of the request, and to cycle the control input through the second state and the at least one additional state after the interval of time has elapsed.
8. The apparatus of claim 1 , further comprising a user interface, wherein the request is accepted via the user interface.
9. An apparatus for treating a tumor in a subject's body and facilitating delivery of a substance across cell membranes in the subject's body, the apparatus comprising:
an AC voltage generator capable of operating at a first frequency between 50 and 500 kHz and a second frequency between 50 and 500 kHz, wherein the second frequency is different from the first frequency, the AC voltage generator having a control input, wherein the AC voltage generator is configured to output the first frequency when the control input is in a first state and to output the second frequency when the control input is in a second state; and
a controller programmed to (a) place the control input in the second state so that the AC voltage generator outputs the second frequency, (b) accept a request to switch to the first frequency, (c) upon receipt of the request, place the control input in the first state so that the AC voltage generator outputs the first frequency for an interval of time, and (d) when the interval of time has elapsed, automatically place the control input in the second state so that the AC voltage generator outputs the second frequency,
wherein the first frequency is selected to increase permeability of the cell membranes and the second frequency is selected to reduce viability of the cells in the tumor, and
wherein the interval of time is between 12 and 72 hours.
10. The apparatus of claim 9 , further comprising:
a set of electrodes configured for affixation to the subject's body; and
wiring that connects an output of the AC voltage generator to the set of electrodes.
11. The apparatus of claim 9 , wherein the first frequency is between 250 kHz and 350 kHz, and the second frequency is between 150 kHz and 250 kHz.
12. The apparatus of claim 9 , wherein the first frequency is between 125 kHz and 175 kHz, and the second frequency is between 75 kHz and 125 kHz.
13. The apparatus of claim 9 , wherein the first frequency is between 75 kHz and 175 kHz, and the second frequency is between 100 kHz and 300 kHz.
14. The apparatus of claim 9 , wherein the controller is further programmed to, subsequent to the receipt of the request, switch the control input back and forth between the first state and the second state.
15. The apparatus of claim 9 , wherein the AC voltage generator is capable of operating at at least one additional frequency between 50 and 500 kHz, and wherein the AC voltage generator is configured to output the least one additional frequency when the control input is in at least one additional state, and
wherein the controller is programmed to cycle the control input through the second state and the at least one additional state prior to receipt of the request, and to cycle the control input through the second state and the at least one additional state after the interval of time has elapsed.
16. A method for treating a tumor in a subject's body and facilitating delivery of a substance across cell membranes in the subject's body, the method comprising:
applying an electric field at a second frequency between 50 and 500 kHz to the tumor, wherein the second frequency is selected to reduce viability of the cells in the tumor;
accepting a request to switch to a first frequency;
upon receipt of the request, applying an electric field at the first frequency between 50 and 500 kHz to the tumor for an interval of time, wherein the first frequency is selected to increase permeability of the cell membranes and wherein the second frequency is different from the first frequency; and
automatically reverting to applying the electric field at the second frequency to the tumor when the interval of time has elapsed,
wherein the interval of time is at least 12 hours.
17. The method of claim 16 , wherein the first frequency is between 250 kHz and 350 kHz, and the second frequency is between 150 kHz and 250 kHz.
18. The method of claim 16 , wherein the first frequency is between 125 kHz and 175 kHz, and the second frequency is between 75 kHz and 125 kHz.
19. The method of claim 16 , wherein the first frequency is between 75 kHz and 175 kHz, and the second frequency is between 100 kHz and 300 kHz.
20. The method of claim 16 , wherein the interval of time is between 12 and 72 hours.