UNC-Chapel Hill researchers use light to launch drugs from red blood cells

CHAPEL HILL, N.C.—Let there be light...and perhaps better drug delivery. Researchers at the University of North Carolina (UNC) at Chapel Hill have developed a “breakthrough” technique that uses light to activate a drug stored in circulating red blood cells so that it can be released for precisely to act when and where it is needed.

 

The work, led by Fred Eshelman Distinguished Professor David Lawrence in the Eshelman School of Pharmacy, could have “profound implications for the field of drug delivery,” UNC says, by using red blood cells to carry drugs and then using light to release them in precise locations. The technique, which overcomes a decades-long scientific hurdle with drug delivery, could drastically reduce the amount of a drug needed to treat disease and thus diminish side effect problems as well.

 

“Using light to treat a disease site has a lot of benefits beyond the ‘isn’t-that-cool factor’,” said Lawrence, whose work is published in the journal Angewandte Chemie. “Those benefits could include avoiding surgery and the risk of infection, making anesthesia unnecessary and allowing people to treat themselves by shining a light on a problem area, such as an arthritic knee.”

 

In their work, Lawrence and his team attached a drug molecule to vitamin B12 and loaded the compound into red blood cells. Because these cells can circulate for up to four months, that provides the means for a long-lasting reservoir of medicine that can be tapped as needed. They then utilized long-wavelength light to penetrate deep enough into the body to break molecular bonds—in this case, the drug linked to vitamin B12.

 

However, therein lay another challenge. While long-wavelength light can penetrate deeply into the body, it doesn’t carry as much energy as short-wavelength light. As a result, it typically cannot break molecular bonds.

 

Lawrence’s team solved that energy problem by introducing a weak energy bond between vitamin B12 and the drug and then attached a fluorescent molecule to the bond. The fluorescent molecule acts as a sort of “antenna,” capturing long-wavelength light and using it to cut the bond between the drug and the vitamin carrier.

 

Lawrence pointed to some complex and deadly cancers where physicians might have a better chance of helping the patient if a wide array of anticancer agents could be used.

 

“The problem is when you start using four or five very toxic drugs you’re going to have intolerable side effects,” he said. “However, by focusing powerful drugs at a specific site, it may be possible to significantly reduce or eliminate the side effects that commonly accompany cancer chemotherapy.”