Findings hold important implications for cancer therapy.
The application of nanotechnology in the field of drug delivery has attracted much attention in recent years. In cancer research, nanotechnology holds great promise for the development of targeted, localized delivery of anticancer drugs, in which only cancer cells are affected.
Such targeted-therapy methods would represent a major advance over current chemotherapy, in which anticancer drugs are distributed throughout the body, attacking healthy cells along with cancer cells and causing a number of adverse side effects.
By carrying out comprehensive studies on mice with human tumors, UCLA scientists have obtained results that move the research one step closer to this goal.
"Our present study shows, for the first time, that MSNs are effective for anticancer drug delivery and that the capacity for tumor suppression is significant," Tamanoi said.
"Two properties of these nanoparticles are important," Lu said. "First, their ability to accumulate in tumors is excellent. They appear to evade the surveillance mechanism that normally removes materials foreign to the body. Second, most of the nanoparticles that were injected into the mice were excreted out through urine and feces within four days. The latter results are quite interesting and might explain the low toxicity observed in the biocompatabilty experiments we conducted."
Researchers at the Nano Machine Center for Targeted Delivery and On-Demand Release are modifying MSNs — which are easily modifiable — so that the nanoparticles can be equipped with nanomachines. For example, nanovalves are being attached at the opening of the pores to control the release of anticancer drugs. In addition, the interior of the pores is being modified so that the light-induced release of anticancer drugs can be achieved.
"We can modify both the particles themselves and also the attachments on the particles in a wide variety of ways, which makes this material particularly attractive for engineering drug-delivery vehicles," Zink said.
The team is now planning future research that involves testing MSNs in a variety of animal-model systems and carrying out extensive studies on the safety of MSNs.
"Comprehensive investigation with practical dosages which are adequate and suitable for in vivo delivery of anticancer drugs is needed before MSNs can reach clinics as a drug-delivery system," Tamanoi said.
The research received support from National Institutes of Health and the National Science Foundation. In addition, NanoPacific Holdings Inc. provided critical support for the animal experiments.
The California NanoSystems Institute at UCLA  is an integrated research center operating jointly at UCLA and UC Santa Barbara whose mission is to foster interdisciplinary collaborations for discoveries in nanosystems and nanotechnology; train the next generation of scientists, educators and technology leaders; and facilitate partnerships with industry, fueling economic development and the social well-being of California, the United States and the world. The CNSI was established in 2000 with $100 million from the state of California and an additional $250 million in federal research grants and industry funding. At the institute, scientists in the areas of biology, chemistry, biochemistry, physics, mathematics, computational science and engineering are measuring, modifying and manipulating the building blocks of our world — atoms and molecules. These scientists benefit from an integrated laboratory culture enabling them to conduct dynamic research at the nanoscale, leading to significant breakthroughs in the areas of health, energy, the environment and information technology.
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