Targeted Drug Delivery
Today modern medicine provides patients with numerous drugs for an enormous number of health issues. For example, getting relief from a headache can be as simple as popping open a bottle of aspirin and swallowing a couple pills. While to the patient the delivery of the drug begins and ends with swallowing those two pills with a glass of water, to the scientists working on the drug that’s simply the beginning of numerous steps that hopefully result in a drug surviving the trip through the body to it’s intended target and doing it’s job.
Drugs are therefore designed not just to solve a problem but to survive the human body’s natural mechanisms. The gauntlet of obstacles that a drug faces upon entry into the body is a major reason why many researchers continue to look into innovative techniques for delivering pharmaceuticals.
That’s where research being conducted by Drs. Stefan Franzen and Steve Lommel comes in. Working with the red clover necrotic mosaic virus (RCNMV), Drs. Franzen and Lommel have developed a potential revolutionary drug delivery platform.
Figure 1. Production of Drug Vector
Drs. Franzen and Lommel take advantage of a 17 nanometer space within the 38 nanometer icosahedral capsid of RCNMV in order to store therapeutics. The RCNMV infused with the drugs could then be used to deliver the drugs in a cell specific manner with the addition of targeting peptides.
The preparation of the drug carrying virus is elegant in it’s simplicity and produces a robust delivery mechanism (See Fig 1). First RCNMV is treated with EDTA to open pores in the capsid. Next therapeutics are infused through these open pores. The pores are then sealed with Ca²+ which is key in releasing the drug later upon viral entry to the cell. The prepared virus can then be purified via dialysis followed by adding target specific peptides.
The elegance of using Ca²+ to seal the pores lies in the fact that the human bloodstream is abundant in calcium. Inside cells, calcium levels are much lower, allowing the pores to open up thereby delivering the infused therapeutics only when the target cell has been entered.
In vitro work with Doxorubicin, a cancer drug, infused RCNMV shows promising results (see Fig 2.) promoting apoptosis only when provided with targeting peptides allowing the drug to be delivered to the interior of cells.
Figure 2. Delivery of Doxorubicin RCNMV to HeLa cells
A potential application of this research is in cancer treatment. Current chemotherapy treatments often result in dramatic side effects as the drugs do not distinguish between diseased and healthy cells. While these results are probably still years from resulting in a commercial therapy it provides hope that in the near future doctors will be able to prescribe chemotherapy treatments with dramatically reduced side effects thanks to target specific delivery of the drugs.
(Sources: NCSU – results. , NCSU News , Franzen Presentation – Plant Virus Nanotechnology)