In a study using lab-grown cells, Johns Hopkins Medicine researchers specializing in aging report they have successfully delivered a common blood pressure drug directly to the inner membrane of mitochondria, the “power plants” in the cells of humans, animals, plants, and most other organisms.
Developing ways to directly target these energy-producing parts of the cell for delivery of drugs has long been a goal for researchers because mitochondria drive, control or play a role in almost every biological process, including natural cell death and aging. Alterations or declines in mitochondrial activity and pathways are closely aligned with decreased organ function and frailty. But because of the mitochondria’s double-membrane structure, scientists have found it challenging to get drug molecules to penetrate the inner membrane and gain access to core functions of the organelles.
The new study, described in the Aug. 4 issue of PNAS nexus, reports on a method that essentially hijacks a system already used by mitochondria to transport oxygen and other chemicals to the inner membrane.
For the study, the researchers lab-synthesized three naturally occurring transport proteins that interact with mitochondria. They then fused a commonly prescribed blood pressure medication (losartan) to each of these three proteins to determine which had the highest success rate penetrating the inner membrane of the mitochondria. These fused proteins, dubbed mtLOS1, mtLOS2 and mtLOS3, when introduced to lab-grown cells in separate trials, were able to transport the drug directly to the mitochondria at a significantly higher concentration than was possible with free losartan not fused to the transport protein. This could be seen under a microscope using fluorescence.
In a proof-of-concept experiment, the researchers also tested a “scrambled” version of mtLOS, which was unable to penetrate the inner membrane.
