Scientists perform surgery on cell
Scientists perform surgery on cell
New procedure called world’s most precise
By GARETH COOK Boston Globe
Sunday, November 23, 2003
Cambridge — Harvard University scientists say they have performed the world’s most precise surgery, using a sophisticated new laser scalpel that can make tiny incisions within a single living cell.
Using this procedure, the team has cut out tiny elements of a cell without affecting the cell’s surface. In one experiment, they vaporized an individual mitochondrion, a microscopic structure that powers cells, without harming the cell in which it was floating.
The advance, not yet published in a scientific journal, puts a powerful tool in the hands of biologists in a booming area called mechanobiology. Even as the life sciences have been swept by the power of genetics, a growing number of scientists have been searching for the roots of diseases from hypertension to diabetes to heart failure in the physical structures of a cell. The Harvard laser system will allow them to dismantle a living cell with unprecedented precision and observe the results.
“At the turn of the last century, everyone talked about mechanical forces, but that was lost,” said Don Ingber, who collaborated on the research and is professor of pathology at Harvard Medical School and Children’s Hospital. “There has been a renaissance over the last 15 years, and this provides a new opportunity.”
The scientists have named the technique nanosurgery because it is surgery to the scale of a nanometer, or one-billionth of a meter.
The team uses extremely brief laser pulses, aimed through a microscope, to obliterate whatever lies at the point of focus, according to a paper describing the work. The result is an inverted cone of ruby red light that can shine through a cell but, at its point, make a cut just 300-billionths of a meter wide, less than one- hundredth the diameter of a human hair.
The system is an improvement on previous approaches, because it can make such a cut so small that nearby structures are unaffected.
The work, which was mostly done in mouse-skin cells, could find applications in a range of biological research. The scientists cautioned that it was too early to discuss direct medical applications, in part because the human body is made of many trillion cells and in part because the technology is so new.
“We are still in the Stone Age of laser nanosurgery,” said Eric Mazur, who led the team and is a professor of applied physics at Harvard.
One of the great difficulties of using a laser to operate on the cell is the danger that the powerful beam will deliver too much energy and destroy the entire cell. To overcome this, the team built a laser that uses pulses measured in femtoseconds, which are thousandths of trillionths of seconds. A femtosecond is so vanishingly brief that light cannot make it across an average-size room in even a million femtoseconds.
The laser was also built to emit 1,000 bursts every second, which is considered low in the world of physics.
This laser is then directed through a maze of mirrors and down the eyepiece of a microscope. When the laser is turned on, a burst of light passes easily through the cell, which is largely transparent. But at the tiny point where it comes to focus, the laser light is extremely intense, the way sunlight shining through a magnifying glass can burn a leaf if the light is focused to a dot.
“It is an exciting tool,” said Paul Matsudaira, who was not involved in the research and is director of the Whitehead Institute- MIT BioImaging Center.