A nanoparticle drug delivery system can safely transport a powerful anticancer drug through the bloodstream, the researchers report.
The nanoparticles are derived from chitin, a natural and organic polymer that, among other things, makes up the outer shells of shrimp.
Drug administration is a recurring enigma in the treatment of cancer. Scientists have developed many anti-cancer therapies, but these drugs often affect healthy tissues, and the drugs can break down in the blood before reaching the site of the tumor.
Nanoparticles are a promising type of drug delivery system. But their effectiveness as drug carriers and protectors against drugs, as well as the potential toxicity to patients, depends significantly on their size, composition and chemical properties.
Balancing these factors is a delicate process. Although researchers have made significant advances in nanomedicine over the past decade, it remains a formidable challenge to design and synthesize stable nanoparticles that could deliver enough drugs to treat solid tumors.
Nanoparticles with chitin, the possible solution?
The team of Migin Zhang, a professor of materials science and engineering and neurological surgery at the University of Washington, has shown that their chitin-derived system can successfully transport Taxol – a powerful anticancer drug, also known as paclitaxel – through the bloodstream and can inhibit tumor growth and spread in mice.
The nanoparticles showed no adverse side effects.
“This could be the basis for a new class of nanoparticle delivery systems that can transport anti-cancer treatments through the body safely, without toxic side effects from the nanoparticle material,” says Miqin Zhang.
The nanoparticles, once loaded with Taxol, have a diameter of about 20.6 nanometers – ie almost 1/4000 the width of a human hair. The particles are small enough to travel through blood vessels and reach tumor sites.
The team subjected the nanoparticles loaded with Taxol to a series of experiments to see what they could do to the tumors.
In mouse breast cancer cell cultures, most cancer cells showed signs of cell death 48 hours after treatment, indicating that nanoparticle-associated Taxol could enter cancer cells and at least affect cell growth.
In mice, Taxol-loaded nanofibers, which decomposed into nanoparticles, showed 90% inhibition of breast tumor growth, compared with approximately 66% inhibition for the widely used Taxol injected.
The nanoparticles also inhibited melanoma tumor growth in mice by up to 75%. In separate experiments in mice, Taxol-loaded nanoparticles prevented the spread of breast cancer to other parts of the body, unlike Taxol.
Longer circulation of the drug, a sign of efficiency
In addition to these promising findings, the team found that the nanoparticles keep Taxol in the blood for a longer period of time, giving the drug more time to reach the tumor site.
In the bloodstream of mice, the plasma half-life of nanoparticles associated with Taxol was almost 25 hours, compared to less than 2 hours for Taxol.
Mice injected with nanofibers did not show toxic side effects, indicating that the nanoparticles themselves do not cause tissue damage. This is while the widely used clinical solution for Taxol can cause liver toxicity in mice, among other side effects.
Zhang believes that chitin-derived nanoparticles could form the basis of a non-toxic drug delivery system for cancer, which keeps the body in the body longer to inhibit tumor growth and metastasis.
Nanoparticles have all the characteristics you could hope for in order to get the drug against tumor cells.