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Robo-Bacteria Engineered for Cancer Drug Delivery

Sylvain Martel

Sylvain Martel (Polytechnique Montréa)

16 August 2016. A biomedical engineering team designed a technology for precise deployment of drugs to tumors with bacteria modified to deliver their cargoes. The system designed by researchers from Polytechnique Montréal, Université de Montréal, and McGill University in Quebec, Canada is described in yesterday’s issue of the journal Nature Nanotechnology (paid subscription required).

Computer engineering professor Sylvain Martel at Polytechnique Montréal and colleagues are seeking better delivery mechanisms for cancer drugs, which today are often given systemically, such as chemotherapy, causing adverse side effects in many patients. Even more targeted treatments, such as radiation, can harm nearby healthy tissue. Thus delivery of cancer-killing drugs directly to tumors is an unmet medial need.

One of the main obstacles to more precise delivery of drugs is the intense activity of cancer cells that depletes oxygen from the immediate tumor region, and makes tumors resistant to many therapies. The system designed and tested by the research team harnesses bacteria with an ability to penetrate these low-oxygen zones, and carry cancer-killing drugs directly to their targets.

The microbes in this case are a strain of Magnetococcus marinus bacteria with the unusual ability to respond to magnetic forces, a result of mineral crystals in their outer membranes that enable the organisms to naturally position along the Earth’s geomagnetic field. The team added chains of iron oxide nanocrystals to the bacteria to bolster their magnetic response. Another feature of these bacteria is their affinity for low-oxygen environments, which helps target the tumors.

In their paper, researchers engineered the bacteria further to carry cancer drugs in nanoscale lipid, or natural oil, containers, with some 70 of these tiny containers attached to each organism. The modified bacteria were then injected in lab mice grafted with human colon cancer cells near the site of the tumors, and guided by an external magnetic field. The results show 55 percent of the engineered bacteria penetrated inside the low-oxygen regions of the tumors.

“These legions of nanorobotic agents were actually composed of more than 100 million flagellated bacteria,” says Martel in a Polytechnique Montréal statement, “and loaded with drugs that moved by taking the most direct path between the drug’s injection point and the area of the body to cure. The drug’s propelling force was enough to travel efficiently and enter deep inside the tumors.”

For Martel’s group, however, these findings are one step in the direction of a more advanced technology. “This innovative use of nanotransporters,” adds Martel, “will have an impact not only on creating more advanced engineering concepts and original intervention methods, but it also throws the door wide open to the synthesis of new vehicles for therapeutic, imaging and diagnostic agents.”

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