Engineers from Massachusetts Institute of Technology developed a new microfluidic device that will temporarily open up membrane pores to let DNA in and allow genetic engineering to do its work.
The results of their study have been published in this week’s Scientific Reports.
The process of genetically engineering any organism means the scientists first need to make the cells accept foreign DNA. To do this, electroporation is done to expose the cells to an electric field.
What this process does is open up the pores within the cell membrane, allowing new DNA to flow inside. The challenge here is that it takes scientists a long time to figure out the exact electric field that needs to be applied so that the membrane opens up.
“We’re trying to reduce the amount of experimentation that’s needed,” says Cullen Buie. “Our big vision for this device and future iterations is to be able to take a process that usually takes months or years, and do it in a day or two.”
Scientists have other ways of doing electroporation by using simple instruments that come with a set of instructions to open up the cell’s membrane. Each system may include instructions for roughly 100 different organisms, such as strains of bacteria and yeast, each of which requires a unique electric field and set of experimental conditions for permeation. MIT Professor Buie says that the number of organisms for these instructions are just a fraction of what really exists in nature.
“There’s a tremendous amount of biodiversity we’re unable to access,” Buie says. “Part of the problem is, we can’t even get the DNA in, much less get it expressed by the organism. And for electroporation, the search for the conditions that might work is like a shot in the dark.”
“It’s like surgery — this is pretty invasive,” Buie says. “There’s a sweet spot between killing them and not affecting them at all, that you need to find to be able to open them reversibly, just enough so that DNA gets in and they reseal on their own.”
Notably, for some organisms, it could take years to develop conditions so that the cell will survive the process.
This new microfluidic device may shorten the time it takes to know these ideal conditions, so the scientists can apply the correct amount of electric field on the membrane.
The researchers placed several strains of cells from bacteria through the device, exposing these cells to an electric field. A fluorescent marker was added that that it will light up in the presence of DNA. Once the cells are diffused with the electric field, they will let in the fluorescent marker and thus light up. This translates to the cell’s response to its own genetic material.
To identify the magnitude of the electric potential that was able to open a cell membrane, the researchers simply marked the location of each fluorescent cell along the channel.
“In one experiment, you can test a range of electric fields and get some information almost instantly, in terms of whether there’s been something successful in opening pores,” Buie says. “So now, in your searching process, you don’t need to run a bunch of different experiments and test different electric fields separately. You can do it in one go, and it literally lights up.”