The Use of Magnetic Bacteria in Drug Delivery

A recent article published in the journal Nature Nanotechnology shows that using magnetic bacteria could be a more successful method for delivering drugs to tumors. The major issue encountered when designing cancer therapies is finding a way to deliver chemotherapy drugs to only the tumors, keeping healthy tissues unaffected. Nanocarriers, which are small particles that transfer drugs, have been developed to do just that. As they circulate through the body, they target only the cancer cells. However, since they depend on the circulatory system to travel to the tumor, a large portion is filtered out of the body and never reaches the tumor. They also have trouble getting inside the tumor due to a difference in pressure between the tumor and its surrounding tissue. Therefore, the nanocarriers never reach the hypoxic zones of the tumor, which are the site of active cell division. These zones have very low oxygen content. If a procedure can be found to deliver the drugs to these regions, the metastasis rate will greatly decrease. That is what the authors set out to do.

            The researchers found that a bacteria known as magnetococcus marinus (MC-1), which is already present in nature, could be used since they thrive in areas of water with low oxygen. MC-1 contains a chain of magnetic nanocrystals, which work like the needle of a compass. When in the Northern Hemisphere, the nanocrystals cause the bacteria to travel in a northern direction. MC-1 is also comprised of sensors that can detect changes in oxygen levels. These two components aid the bacteria in finding the tumor and sustaining their location in the low oxygen area. Once reaching the tumor, the magnetic field is turned off. The bacteria then rely on the sensors to locate the hypoxic zones.

            Experiments were performed to test the use of MC-1 as a treatment for tumors. The study was conducted on mice, and they found that the bacterial cells were located deep inside the tumor, specifically in low oxygen areas. Then, the researchers attached vesicles, containing the drugs, to the cells to test their effect on penetration into the tumors. An estimated 55 % of the cells with attached vesicles successfully traveled into the tumor versus current nanocarriers only transporting about 2% of the drugs into the tumor. This exhibits the effectiveness of the method and proves promising for the treatment of tumors.

            The researchers plan to look at the effect of the bacterial cells on tumor size reduction. They also want to investigate if other types of cancer-killing medicines can be delivered via MC-1. This study provides advancements in current methods that have huge implications for those suffering from cancer. Drug delivery that specifically targets the tumors diminishes side effects and makes the treatment more successful. This research and future studies stemming from it will provide enormous potential for improved cancer treatment.

Reference:

Magneto-aerotactic bacteria deliver drug-containing nanoliposomes to tumour hypoxic regions. Felfoul O, Mohammadi M, Taherkhani S de Lanauze D, Zhong Xu Y, Loghin D, Essa S Jancik S, Houle D, Lafleur M, Gaboury L, Tabrizian M Kaou N, Atkin , Vuong T, Batist G, Beauchemin N, Radzioch D, Martel S. Nat Nanotechnol. 2016 Aug 15.

Link to the abstract: http://www.ncbi.nlm.nih.gov/pubmed/27525475

National Institute of Biomedical Imaging and Bioengineering Resource: http://www.nibib.nih.gov/news-events/newsroom/swarms-magnetic-bacteria-could-be-used-deliver-drugs-tumors