The ability to convert, or “reprogram,” cells into other types has raised hopes for regenerating damaged limbs and organs. But existing methods are risky or inefficient and have been tried only on laboratory animals. A new technology could overcome these limitations, however. Researchers have used it to restore injured mouse legs and claim the technique is safe enough to test in humans.

Cells are typically reprogrammed using mixtures of DNA, RNA and proteins. The most popular method uses viruses as a delivery vehicle—although they can infect unintended cells, provoke immune responses and even turn cells cancerous. One alternative, called bulk electroporation, exposes cells to an electric field that pokes holes in their membranes to let in genetic material and proteins. Yet this method can stress or kill them, and only a small proportion is

Tissue nanotransfection, described in a study published in August in Nature Nanotechnology, involves a chip containing an array of tiny channels that apply electric fields to individual cells. “You affect only a small area of the cell surface, compared with the conventional method, which upsets the entire cell,” says study co-author James Lee, a chemical and biomolecular engineer at The Ohio State University. “Essentially we create a tiny hole and inject DNA right into the cell, so we can control the dosage.”

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In cover image: Researchers demonstrate a process known as tissue nanotransfection at the Ohio State University Wexner Medical Center. In laboratory tests, this process was able to heal the badly injured legs of mice in just three weeks with a single touch of this chip. Credit: Ohio State University Wexner Medical Center