The unique properties of the hollow shell nano-particles, known as polymersomes, allow them to deliver two distinct drugs, paclitaxel (marketed as Taxol by Bristol-Myers Squibb), and doxorubicin directly to tumors implanted in mice.
While cell membranes and liposomes are created from a double layer of fatty molecules called phospholipids, a polymersome is comprised of two layers of synthetic polymers. This results in a structure that looks like a very small cell or virus.
The researchers take advantage of the polymersome properties to ferry their drug combination to the tumor. The large polymers making up the shell allow paclitaxel, which is water-insoluble, to embed within the shell. Doxorubicin, which is water-soluble, stays within the interior of the polymersome until it degrades.
“The system provides a number of advantages over other Trojan horse-style drug delivery system, and should prove a useful tool in fighting a number of diseases,” said Dennis Discher, a professor in Penn’s School of Engineering and Applied Science and a member of Penn newly established Institute for Translational Medicine and Therapeutics. “Here we show that drug-delivering polymersomes will break down in the acidic environment of the cancer cells, allowing us to target these drugs within tumor cells.”
“Recent studies have shown that cocktails of paclitaxel and doxorubicin lead to better tumor regression than either drug alone, but there hasn’t been any carrier system that can carry both drugs as efficiently to a tumor,” added Fariyal Ahmed, the lead author and a fellow at Harvard Medical School. “Polymersomes get around those limitations.”
This research was supported by grants from the US National Institutes of Health, the National Science Foundation-Materials Research Science and Engineering Center and the Nanotechnology Institute. The findings were published in the journal Molecular Pharamaceutics.