A team led by Nicholas Melosh, an associate professor of materials science and engineering, first began testing nanostraws about five years ago using relatively tough cell lines derived from cancers, mouse cells and other sources. Now, Melosh and colleagues have shown the technique works in human cells as well, a result that could speed up medical and biological research and could one day improve gene therapy for diseases of the eyes, immune system or cancers.
“What you’re seeing is a huge push for gene therapy and cancer immunotherapy,” said Melosh, who is also a member of Stanford Bio-X, Stanford ChEM-H and the Wu Tsai Neurosciences Institute, but existing techniques are not up the challenge of delivering materials to all the relevant human cell types, especially immune cells. “They’re really tough compared to almost all other cells that we’ve handled,” he said.
Crossing the cell membrane
The idea of transporting chemicals across the cell membrane and into the cell itself is not new, but there are a number of problems with the methods scientists have until now relied on. In one common method, called electroporation, researchers use an electric current to open up holes in cell walls through which molecules such as DNA or proteins can diffuse through, but the method is imprecise and can kill many of the cells researchers are trying to work with.
In another method, researchers use viruses to carry the molecule of interest across a cell wall, but the virus itself carries risks. While there are similar methods that replace viruses with more benign chemicals, they are less precise and effective.
That was the state of affairs until just five or six years ago, when Melosh and colleagues came up with a new way of getting molecules into cells, based on Melosh’s expertise in nano materials. They would use electroporation, but do it in a vastly more precise way with nanostraws, which because of their relatively long, narrow profile help concentrate electric currents into a very small space.
At the time, they tested that technique on animal cells sitting atop a bed of nanostraws. When they turned on an electric current, the nanostraws opened tiny, regularly sized pores in the cell membrane—enough that molecules can get in, but not enough to do serious damage.
The electric current served another purpose as well. Rather than waiting for molecules to randomly float through the newly opened pores, the current drew molecules straight in to the cell, increasing the speed and precision of the process. The question at that time was whether the technique would be as effective on the kinds of human cells clinicians would need to manipulate to treat diseases.
Read more at: PHYS.org