Researchers Use Light to Launch Drugs From Red Blood Cells

Technique could reduce drug levels needed to treat diseases

Scientists at the University of North Carolina (UNC) at Chapel Hill have developed a new technique that uses light to activate a drug stored in circulating red blood cells so that the drug is released exactly when and where it is needed. The process, which overcomes a decades-long scientific hurdle, could drastically reduce the amount of medications needed to treat disease, thereby reducing adverse effects, according to the researchers.

“Using light to treat a disease site has a lot of benefits beyond the ‘isn’t that cool’ factor,” said Professor David Lawrence of the Eshelman School of Pharmacy. “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.”

Lawrence and his team attached a drug molecule to vitamin B12 and loaded the compound into red blood cells, which can circulate for up to four months, providing a long-lasting reservoir of medication that can be tapped as needed. They then demonstrated their ability to overcome a longtime technical hurdle: using long-wavelength light to penetrate deep enough into the body to break molecular bonds––in this case, the drug linked to vitamin B12.

Long-wavelength light can penetrate much more deeply into the body, but it doesn’t carry as much energy as short-wavelength light and cannot typically break molecular bonds. To activate the drug with long-wavelength light, Lawrence and his team had to figure out how to do it in a way that required less energy.

“That’s the trick, and that’s where we’ve been successful,” he said.

The scientists solved the 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 an 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.”

Lawrence has created a company, Iris BioMed, in partnership with UNC to further develop the technology in human subjects.

Source: UNC–Chapel Hill; January 4, 2017.