Swarms of magnetically-guided bacteria can target tumors with nano-sized chemo agents

By John Murphy, MDLinx
Published August 17, 2016

Key Takeaways

Scientists in Canada have developed a breakthrough technique in which magnetotactic bacteria, loaded with chemo-containing nanoliposomes, can be precisely and externally guided to hypoxic areas of tumor cells, according to an article published online August 15, 2016 in Nature Nanotechnology.

Hypoxic regions of tumors are generally resistant to most therapies. This new nano-sized delivery method not only zeros in on these hypoxic regions, but also spares the surrounding areas from excess exposure to chemotherapeutic drugs, the scientists noted.

Unlike robotic nanocarriers—which rely on bloodstream circulation to carry them to tumors—the swarms of bacterial nanocarriers in this investigation move by their own power, and they have a self-directed “guidance system” to locate hypoxic regions. While other studies have shown that robotic nanocarriers reach the tumor with only a fraction of their payload intact, about 55% of the bacterial nanocarriers in this study penetrated the hypoxic regions in tumor cells.

“These legions of nanorobotic agents were actually composed of more than 100 million flagellated bacteria—and therefore self-propelled—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,” said lead investigator Sylvain Martel, PhD, Director of the Nanorobotics Laboratory at Polytechnique Montréal.

Dr. Martel and colleagues used magnetotactic bacteria, the Magnetococcus marinus strain MC-1, which contain magnetic iron-oxide nanocrystals. These bacteria innately swim along local magnetic field lines and toward low-oxygen concentrations.

The investigators injected the cells near colorectal tumor sites in mice. The researchers externally and precisely guided the swarms toward the tumors using a directional control instrument that created a magnetic field.

“The drug’s propelling force was enough to travel efficiently and enter deep inside the tumors,” explained Dr. Martel, who is also the Canada Research Chair in Medical Nanorobotics.

Several thousand MC-1 cells comprised a swarm, with each MC-1 cell loaded with about 70 chemo-containing nanoliposomes.

“Chemotherapy, which is so toxic for the entire human body, could make use of these natural nanorobots to move drugs directly to the targeted area, eliminating the harmful side effects while also boosting its therapeutic effectiveness,” Dr. Martel said.

“This innovative use of nanotransporters 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,” he added.

See the bacterial swarms in action in this video from Polytechnique Montréal.

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