New process "electroports" gene therapy agents into living cells
By Ben Coxworth
October 18, 2011
One of the key processes in gene therapy involves taking cells from the patient, injecting a therapeutic genetic material into them, then reintroducing them to the patient's body and letting them go to work. Unfortunately, getting that material into the cells can be tricky. While larger cells can actually be punctured with a fine needle, most human cells are too small for that approach to be possible. There are also methods of inserting random amounts of material into bulk quantities of cells, but these are inexact. Now, however, scientists at Ohio State University are reporting success with a process known as "nanochannel electroporation" (NEP), in which therapeutic biomolecules are electrically shot into cells.
NEP utilizes a stamped polymer electronic device, incorporating two linked reservoirs. A cell is suspended in place in one of those reservoirs, while the therapeutic agent is contained in the other. The two reservoirs are linked by a nanometer-scale channel, made by stretching a gold-coated DNA strand between them, then etching that strand away.
Electrodes within the channel send electrical pulses of a few hundred volts from the agent's reservoir towards the cell's reservoir, creating an electrical field where the nanochannel opens into the cell's reservoir. This field interacts with the cell's natural electrical charge, causing a hole to open in the cell membrane. This hole is large enough to admit the therapeutic agent that is flowing in through the nanochannel, but not large enough to kill the cell.
Dosages are controlled by varying the number of pulses, and the width of the nanochannel.
In tests of the system, the Ohio State researchers were able to insert therapeutic RNA into leukemia cells within just 5 milliseconds. When the pulses were lengthened to 10 milliseconds, almost all of the cells were killed. For comparison, some cells were injected with harmless RNA, and those cells lived.
In its present state of development, NEP can't be used on any more than several cells at a time, making it useful mainly for research. A mechanical cell-loading system capable of treating up to 100,000 cells simultaneously is in the works, however, which could make NEP treatments possible.
A paper on the research was recently published in the journal Nature Nanotechnology.