A team of MIT engineers has created a microfluidic device that simplifies the process of getting an organism’s cells to accept foreign DNA, a necessary step before genetic engineering is possible.
The most common way of carrying out this task is by subjecting the targeted cells to an electric field, a procedure called electroporation. The hope is to generate the precise type of field that will cause pores in the cell to open and let DNA in. In practice, getting the intensity of the field right takes time and experimentation.
This new device could change that. The MIT researchers, led by mechanical engineering professor Cullen Buie, claim that it is able to quickly determine the exact electric field that promises to briefly open a cell’s pores without damaging it. They believe that the device can be used on any type of cell, in which case the task of genetic engineering would be made much simpler.
The process of electroporation is not new, but the amount of testing and experimentation currently needed is significant. The team’s device could shorten a job that normally takes at least several months down to one or two days. They released their findings in the journal Scientific Reports earlier this week.
Until now, researchers hoping to experiment with electroporation have had to manage with simple tools that come with specific instructions for puncturing the cells of particular organisms. While each of the currently available systems might be capable of working with several dozen organisms, they remain limited to the ones encoded in the device. According to Buie, only a very small percentage of organisms on the planet are cataloged in the available systems.
What makes electroporation difficult is the high level of accuracy required for the cell to take in the new DNA without being damaged or killed in the process.
In fact, Buie compares the technique to surgery, pointing out that there is a “sweet spot” for successful permeation of cell membranes. If the electric field lacks sufficient strength, the membrane may not be effectively punctured. If it is too strong, the cell can be harmed or even killed in the process.
The team’s device appears to considerably decrease of the amount of trial and error needed to find that sweet spot. It works by utilizing a channel that is impressed into the device using a technique called soft lithography. This channel works by transmitting a variety of electric potentials when the device is exposed to an electric field, allowing scientists to test a range of conditions at once.
The researchers began by testing the device on multiple strains of bacteria. This involved a fluorescent marker designed to light up if it detected DNA. That way, if a cell membrane were to be punctured effectively, the marker would enter the membrane and then light up, having detected the organism’s DNA. At the same time, the channel in the device could be used to keep track of the cells lit up by the marker. By marking those cells, the scientists were able to discover the exact conditions needed to penetrate each specific cell. So far, the MIT team has inserted DNA with success into strains of Mycobacterium smegmatis and E. coli bacteria.
A second set of experiments attempted to permeate bacterial cells with antibiotic-resistant DNA. The researchers verified that the DNA was accepted by performing a streak test, a process in which the cells were grown on a plate in the presence of antibiotics. The cells successfully reproduced, demonstrating that the experiment worked.
If future trials report similar levels of success, this new device could be a step forward for the field of genetic engineering. According to the team, this could have implications for applications as diverse as cancer treatments and the discovery of new drugs.