Charged polymers unlock door to deliver nanoparticles to cancer cells
By Darren Quick
February 11, 2014
Immunofluorescence image shows nanoparticles targeted to endothelial cells – the red particles turn orange when overlapping with the green caveolin in the lipid rafts of the cells (Image: Julia Voigt / Prasad Shastri)
In recent years, we've seen various research efforts looking to specifically target cancer cells as a replacement for the shotgun approach employed by chemotherapy that also damages healthy cells. The trick is to develop a delivery vehicle that identifies and targets only cancer cells, while ignoring the healthy ones. Researchers have found charged polymers have this ability, opening the door for nanoparticles containing cancer-fighting drugs to deliver their payload directly to the cancer cells.
Previous approaches we've seen rely on coating nanoparticles with molecules that are recognized by receptors on the cancer cells that grant access for the delivery of drugs into the cancer cell. However, scientists at the University of Freiburg in Germany say these receptors can change, cutting off access to the cancer cell. The research team has developed a new approach that doesn't rely on these receptors.
The team targeted the endothelial cells that make up the blood vessels that supply tumors with constant nourishment. The cell membrane of endothelial cells contains a large amount of a structure called caveolae, which are "lipid rafts" and act as one of the gatekeepers to the cells. The research team, led by Prof. Prasad Shastri, found that decorating nanoparticles made of lipids with negatively charged ions allowed the nanoparticles to preferentially enter the cancer cells through this door.
"How exactly these charged polymers enable the nanoparticles to unlock this door we are not sure yet, but we feel confident that with further studies this method could usher in a new approach to delivery of drugs in general,” said Shastri. "This is a remarkable discovery, as it allows for the first time to target a specific cell type purely through biophysical principles, and without using the traditional ligand-receptor approach."
"By going after endothelial cells that make up these blood vessels, we can starve the tumor or kill it with one payload," added Jon Christensen, a co-author on the study published in the Proceedings of the National Academy of Sciences.
Source: University of Freiburg
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