Using pig skin, Harvard team shows that living cells can make lasers

A chunk of store-bought pork skin acting like a laser after being injected with dye.
A chunk of store-bought pork skin acting like a laser after being injected with dye.

It turns out hog skin is good for more than a crunchy chunk of pork rind. Doped with dye, pig-skin fat cells can also shoot out tiny laser beams, a team of researchers at Harvard Medical School revealed this week.

Lasers are focused beams of light and are typically generated from hard and brittle substances — semiconductors and crystals — which trap light energy in a multitude of wavelengths and let them out in one intense pulse. In medicine, surgeons and doctors use lasers as precision tools to slice through or seal tissue.

In 2011, a Harvard Medical School team led by professor Seok-Hyun “Andy” Yun and post-doctoral researcher Malte Gather showed for the first time that living cells could “lase” — trapped between mirrors, and injected with a fluorescent dye, human kidney cells grown in a lab glowed when they were pulsed with light. Not only did they emit laser beams, they survived the light show.

This week in the journal Nature Photonics, Yun’s team showed how living cells can pull off that trick. One key is ditching the external equipment: instead of aiming an array of mirrors at the cells, Yun’s team found that a tiny droplet of oil contained within each cell could effectively collect and focus the light.

Up to that point, Yun and his colleagues had been working with lab-grown cervical cancer cells. But once they found that oils were key to focusing the laser, the researchers set out to find the fattiest tissue they could get their hands on.

“We went to the grocery store and bought pig meat,” Yun said.

Cell-based lasers are much more feeble than the machine-made variety, but Yun said they could serve a different purpose within the body one day.

Rather than slice through tissue, for example, laser-emitting cells could serve as a homing device for disease. Since immune cells can already track down invaders, those cells could theoretically be transformed into laser-emitting varieties that would send out a signal when they spot an intruder, targeting specific locations where a cancer has spread.

“It’s a beacon signal, to tell you where your targets are,” Yun said.

There are still several hurdles to be cleared — for example, the cells are still dependent on an external light source to activate them. But the new results bring the team one step closer to such a scenario, Yun said.

Nidhi Subbaraman writes about science and research. Email her at nidhi.subbaraman@globe.com.
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