Seeing the cell and letting it live.

Seeing the cell and letting it live

One of the difficult things about research on large, living bodies is that in order to take a close look at what's going on inside, you have to take what's inside out. That can throw a kink into the processes under investigation. Now, researchers have taken a first look inside a single cell using a new class of instruments that eventually may make it possible to watch cellular biochemistry inside the body, or to perform "biopsies" without needles or surgery. A group of researchers, led by James Aguayo of Johns Hopkins University in Baltimore, reports in the July 10 NATURE "the advent of the NMR [nuclear magnetic resonance] imaging microscope."

NMR relies on magnetic fields and the rotation of atomic nuclei to generate images (SN:1/25/86,p.59). It compares favorably with advanced X-ray techniques for some diagnostic purposes, such as scanning brain areas covered with a thick layer of bone. But NMR, like X-ray, has been limited to imaging organs or the whole body. Now, by boosting the magnetic fields and refining some of the machinery used, Aguayo's group has been able to get the resolving ability of NMR down to 10 microns, so that it is capable of "seeing" intracellular structures. Cells range in size from about 10 microns to about a millimeter. "We wanted to see what the limits were," Aguayo told SCIENCE NEWS. "We just extended [the technology]."

(A group led by Truman Brown at the Fox Chase Cancer Center in Philadelphia is also developing an NMR microscope, and reported early success with the technology last year. They have not yet been able to get the resolution of the microscope low enough to image intracellular structures.)

According to Aguayo, most conventional techniques for investigating single cells are destructive; electron microscopy, for instance, requires the cell to be coated with platinum. "You can't always tell if what you're seeing is artifact or not," Aguayo says. "With NMR, we don't touch the cell at all. We can follow it through time, watch its development." By showing the structure of cells, and possibly their metabolism, the NMR microscope may eventually tell investigators as much about the pathology of tissue in the body as biopsy does now, Aguayo says. The researchers write that they expect the new technology to have "considerable impact" in biology and materials science as well.