Connecting nanowires to live cells could have many applications

There are a few areas of science where new research is always treated with either elation or downright ridicule. High temperature superconductivity and cold fusion are right on top of the list. In recent times, Korean scientist Woo Suk Hwang did all stem cell researchers a “favour” by helping add this subject to the list by fabricating data in his research papers. So much so that “big” breakthroughs in stem cell research are now met with caution. And that is a reason why the jury is still out on the announcement that Japanese and US scientists have managed to convert normal cells, say from the skin of an adult mouse, into stem cells.

This work, done in mice, still needs refinement or even further breakthroughs before it can be used in humans. Ironically, this study came out two days before the US Congress passed a bill that would lower restrictions on funding for embryonic stem cell research. And a week ago, another US team had announced that it had managed to connect tiny wires to cells without killing the latter — a totally unconnected event now, but it could soon become significant for stem cell research.

First the “big” breakthrough, published in the journal, Nature. Shinya Yamanaka of Kyoto University and some of his American associates took skin cells from an adult mouse and injected them with four genes. These adult cells had specialised into skin cells, and thus could not differentiate into any other tissue. The “injected” genes merged with the genes of the mouse in some cells, and then started making proteins. These proteins in turn made some other genes in the cell to switch on, and then through a chain reaction converted the skin cells into stem cells.

It was a big breakthrough, but still far away from application in human beings. First of all, experience has shown us that what works in a mouse does not always work on human beings. Scientists may have to use more than four genes to trigger the events that convert adult cells into stem cells, and even then the process would be far more complicated. More than 20 per cent of the mice got cancer, which suggests that the process is risky.

Yamanaka thinks he can find a solution to the problem, but his method has been criticised for other reasons, too. He had used viruses to deliver the genes to the cell. Viruses can themselves cause cancer and are thus too dangerous to use in human beings. The scientists have to find an alternative.

Now the second piece of research. At the University of California, Berkeley, and at San Francisco, scientist Peidong Yang and his colleagues grew mouse embryonic cells on a piece of silicon nanowire. Several scientists have attempted connecting nanowires (wires of thickness around one billionth of a metre) to cells, but they had all used force that finally resulted in the death of the cell. Yang used tact instead, and grew embryonic mouse cells and embryonic human kidney cells on the nanowire. The wire penetrated the cells, which lived for two weeks before he stopped the experiment. More than 30 nanowires grew into each cell, and still the cells did not die.

Connecting wires to live cells has many applications, because it is the first step towards manipulating the cells in more ways than one. Yang and his colleagues used this method to deliver genes inside the cell, which immediately opens up a way to deal with adult stem cells. He had also demonstrated the successful delivery and normal function of the gene. Says Akhilesh Pandey, professor at Johns Hopkins University in Baltimore, “This work is interesting because nanowires are a much safer method than viruses to deliver genes to a cell.”

Yang and his colleagues have other plans for this work. They think that they could change the electric potential of the cell by using nanowires. The potential of the cell has a bearing on which way a stem cell will go — whether it will become a kidney or an eye or a heart or any other tissue or organ. This immediately gives us a method to programme the cells into becoming a specific tissue. Says Yang, “Biologists are trying to use chemical methods to control differentiation, but electrical methods will also work.”

That could take a while, and Yang thinks that funding is a big issue in continuing his work. A few days after he said this, the US Congress passed the bill. Yang must be smiling all the way to his lab.