How Nanocylinders Deliver Medicine Better Than Nanospheres

Go With the Flow: Penn Researchers Show How Nanocylinders Deliver Medicine Better Than Nanospheres

• Researchers at the University of Pennsylvania School of Medicine & School of Engineering and Applied Science have discovered a better way to deliver drugs to tumors by using a cylindrical-shaped carrier.
• In this study, the research team used skinny cylindrical nanoparticles composed of synthetic polymers to deliver the anticancer drug paclitaxel to a human lung tumor tissue implanted in mice. Because the cylinders remained in circulation for up to one week after injection, they also delivered a more effective dose, killing more cancer cells and shrinking the tumors to a much greater extent.
• Spherical nanoparticles typically only stay in circulation for a few hours.
• This discovery is also helping scientists understand why some viruses, such as cylinder-shaped viruses like Ebola and H5N1 influenza, are so effective.
• This study appeared online in Nature Nanotechnology in advance of print publication in March 2007.

(PHILADELPHIA) – Researchers at the University of Pennsylvania School of Medicine & School of Engineering and Applied Science have discovered a better way to deliver drugs to tumors. By using a cylindrical-shaped carrier they were able sustain delivery of the anticancer drug paclitaxel to an animal model of lung cancer ten times longer than that delivered on spherical-shaped carriers. These findings have implications for drug delivery as well as for better understanding cylinder-shaped viruses like Ebola and H5N1 influenza.

This study appeared online in Nature Nanotechnology in advance of print publication in March 2007.

“These are particles that go with the flow,” says Dennis E. Discher, PhD, Professor of Chemical and Biomolecular Engineering at Penn’s Institute for Medicine and Engineering. “The blood stream is constantly pumping, and these cylindrical nanoparticles align with the flow and persist in circulation considerably longer than any known spherical particles.”

In this study, the research team used skinny cylindrical nanoparticles composed of synthetic polymers to deliver the anticancer drug paclitaxel to a human lung tumor tissue implanted in mice. The cylinders have diameters as small as 20 nm and lengths approaching the size of blood cells. The paclitaxel shrunk the tumors and, because the cylinders remained in circulation for up to one week after injection, they delivered a more effective dose, killing more cancer cells and shrinking the tumors to a much greater extent. Spherical nanoparticles typically only stay in circulation for a few hours.

The research team used nanoparticles that contained one water-loving chain of a common polymer called polyethyleneglycol (PEG). PEGs are commonly found in everyday items like shampoo and some foods. Although synthetic, PEGs have already been approved as biocompatible to humans, making them ideal carriers, note the researchers.

While these findings could impact the way lung cancer is treated, this discovery of how to more effectively deliver drugs to the body could also improve the treatment of such other illnesses as cardiovascular disease as well as other types of cancers.

This discovery is also helping scientists understand why some viruses are so effective. “Cylindrical delivery systems exist in nature, with two prime examples being the Ebola virus and the H5N1 Influenza virus,” says Discher. “These findings can help us understand how this shape evolved in nature and the advantages of using it for treating people.”

In addition to Discher, Yan Geng, Paul Dalhaimer, Shenshen Cai, Richard Tsai, and Manorama Tewari, all of Penn, and Tamara Minko of Rutgers University, are co-authors. The National Institute of Biomedical Imaging and BioEngineering provided funding for this research. ###

PENN Medicine is a $2.9 billion enterprise dedicated to the related missions of medical education, biomedical research, and high-quality patient care. PENN Medicine consists of the University of Pennsylvania School of Medicine (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System.

Penn's School of Medicine is ranked #2 in the nation for receipt of NIH research funds; and ranked #3 in the nation in U.S. News & World Report's most recent ranking of top research-oriented medical schools. Supporting 1,400 fulltime faculty and 700 students, the School of Medicine is recognized worldwide for its superior education and training of the next generation of physician-scientists and leaders of academic medicine.

The University of Pennsylvania Health System includes three hospitals, all of which have received numerous national patient-care honors [Hospital of the University of Pennsylvania; Pennsylvania Hospital, the nation's first hospital; and Penn Presbyterian Medical Center]; a faculty practice plan; a primary-care provider network; two multispecialty satellite facilities; and home care and hospice.

Contact: Karen Kreeger karen.kreeger@uphs.upenn.edu 215-349-5658 University of Pennsylvania School of Medicine

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