Oxygen-depleted hypoxic regions in the tumour are generally resistant to therapies1. Although nanocarriers have been used to deliver drugs, the targeting ratios have been very low. Here, we show that the magneto-aerotactic migration behaviour2 of magnetotactic bacteria3, Magnetococcus marinus strain MC-1 (ref. 4), can be used to transport drug-loaded nanoliposomes into hypoxic regions of the tumour. In their natural environment, MC-1 cells, each containing a chain of magnetic iron-oxide nanocrystals5, tend to swim along local magnetic field lines and towards low oxygen concentrations6 based on a two-state aerotactic sensing system2. We show that when MC-1 cells bearing covalently bound drug-containing nanoliposomes were injected near the tumour in severe combined immunodeficient beige mice and magnetically guided, up to 55% of MC-1 cells penetrated into hypoxic regions of HCT116 colorectal xenografts. Approximately 70 drug-loaded nanoliposomes were attached to each MC-1 cell. Our results suggest that harnessing swarms of microorganisms exhibiting magneto-aerotactic behaviour can significantly improve the therapeutic index of various nanocarriers in tumour hypoxic regions.

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  1. 1.

    & Hypoxia in cancer: significance and impact on clinical outcome. Cancer Metastasis Rev. 26, 225–239 (2007).

  2. 2.

    , , & Magneto-aerotaxis in marine coccoid bacteria. Biophys. J. 73, 994–1000 (1997).

  3. 3.

    Magnetotactic bacteria. Science 190, 377–379 (1975).

  4. 4.

    et al. Magnetococcus marinus gen. nov., sp. nov., a marine, magnetotactic bacterium that represents a novel lineage (Magnetococcaceae fam. nov., Magnetococcales ord. nov.) at the base of the Alphaproteobacteria. Int. J. Syst. Evol. Microbiol. 63, 801–808 (2013).

  5. 5.

    , & Anaerobic magnetite production by a marine, magnetotactic bacterium. Nature 334, 518–519 (1988).

  6. 6.

    et al. Diversity of magneto-aerotactic behaviors and oxygen sensing mechanisms in cultured magnetotactic bacteria. Biophys. J. 107, 527–538 (2014).

  7. 7.

    & Exploiting tumour hypoxia in cancer treatment. Nature Rev. 4, 437–446 (2004).

  8. 8.

    & Targeting hypoxia in cancer therapy. Nature Rev. Cancer 11, 393–410 (2011).

  9. 9.

    , , , & Efficient tumor targeting of hydroxycamptothecin loaded PEGylated liposomes modified with transferrin. J. Control. Rel. 133, 96–102 (2009).

  10. 10.

    , , , & Limited penetration of anticancer drugs through tumor tissue. Clin. Cancer Res. 8, 878–884 (2002).

  11. 11.

    et al. Bacteria in cancer therapy: a novel experimental strategy. J. Biomed. Sci. 17, 21 (2010).

  12. 12.

    Formation of magnetosomes in magnetotactic bacteria. J. Molec. Microbiol. Biotechnol. 1, 79–86 (1999).

  13. 13.

    , , , & Three-dimensional remote aggregation and steering of magnetotactic bacteria microrobots for drug delivery applications. Int. J. Robot. Res. 33, 359–374 (2014).

  14. 14.

    & Significance of blood vessel leakiness in cancer. Cancer Res. 62, 5381–5385 (2002).

  15. 15.

    , , & High interstitial fluid pressure—an obstacle in cancer therapy. Nature Rev. Cancer 4, 806–813 (2004).

  16. 16.

    , , , & Covalent binding of nanoliposomes to the surface of magnetotactic bacteria acting as self-propelled target delivery agents. ACS Nano 8, 5049–5060 (2014).

  17. 17.

    , & To exploit the tumor microenvironment: passive and active tumor targeting of nanocarriers for anti-cancer drug delivery. J. Control Rel. 148, 135–146 (2010).

  18. 18.

    , , , & Impact of tumor hypoxia and anemia on radiation therapy outcomes. Oncologist 7, 492–508 (2002).

  19. 19.

    , & Hypoxia and radiotherapy: opportunities for improved outcomes in cancer treatment. Cancer Metastasis Rev. 26, 241–248 (2007).

  20. 20.

    & Magnetic targeting for site-specific drug delivery: applications and clinical potential. Expert Opin. Drug Delivery 6, 53–70 (2009).

  21. 21.

    & Modelling magnetic carrier particle targeting in the tumor microvasculature for cancer treatment. J. Magn. Magn. Mater. 293, 639–646 (2005).

  22. 22.

    et al. Automatic navigation of an untethered device in the artery of a living animal using a conventional clinical magnetic resonance imaging system. Appl. Phys. Lett. 90, 114105 (2007).

  23. 23.

    et al. Microscopic artificial swimmers. Nature 437, 862–865 (2005).

  24. 24.

    et al. Bacteria-mediated delivery of nanoparticles and cargo into cells. Nature Nanotech. 2, 441–449 (2007).

  25. 25.

    & Can engineered bacteria help control cancer? Proc. Natl Acad. Sci. USA 98, 14748–14750 (2001).

  26. 26.

    et al. Complete genome sequence of the chemolithoautotrophic marine magnetotactic coccus strain MC-1. Appl. Environ. Microbiol. 75, 4835–4852 (2009).

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This project was initially supported in part by the Canada Research Chair (CRC) Tier 2 in Micro/Nanosystem Development, Fabrication and Validation and by grants from the National Sciences and Engineering Research Council of Canada (NSERC) and the Province of Québec. This work was primarily supported by the Québec Consortium for Drug Discovery (CQDM) and in part by the Research Chair of École Polytechnique in Nanorobotics, Mitacs, and later by the CRC Tier 1 in Medical Nanorobotics. The magnetotaxis system was built with financial help from the Canada Foundation for Innovation (CFI). Preliminary in vivo results were obtained with the financial help of the US National Institutes of Health (NIH) grant no. R21EB007506 from the National Institute of Biomedical Imaging and Bioengineering. The authors thank J. Caron from CQDM for her involvement in the coordination of the project. R. Gladue from Pfizer, R. M. Garbaccio from Merck & Co. and C. Reimer from AstraZeneca R&D are also thanked for their guidance and insights from the pharmaceutical industry. C.C. Tremblay (NanoRobotics Lab.) helped in determining the number of bacteria in samples and T. Johns (Biomat'x, McGill University) in the preparation of liposomes. The authors thank J. Hinsinger (University of Montreal (UdM), Institute for Research in Immunology and Cancer (IRIC)) and the histological team (UdM, IRIC) for tumour histology preparation and D. Gingras (UdM, IRIC) for transmission electron microscopy.

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Author notes

    • Ouajdi Felfoul
    • , Mahmood Mohammadi
    • , Samira Taherkhani
    •  & Danuta Radzioch

    These authors contributed equally to this work


  1. NanoRobotics Laboratory, Department of Computer and Software Engineering, Institute of Biomedical Engingeering, Polytechnique Montréal, Montréal H3T 1J4, Canada

    • Ouajdi Felfoul
    • , Mahmood Mohammadi
    • , Samira Taherkhani
    • , Dominic de Lanauze
    • , Dumitru Loghin
    • , Neila Kaou
    • , Michael Atkin
    •  & Sylvain Martel
  2. Department of Biomedical Engineering, McGill University, Montréal H3A 2B4, Canada

    • Samira Taherkhani
    • , Sherief Essa
    •  & Maryam Tabrizian
  3. McGill University Health Centre, Montréal H4A 3J1, Canada

    • Yong Zhong Xu
    • , Sylwia Jancik
    • , Daniel Houle
    •  & Danuta Radzioch
  4. Department of Chemistry, University of Montréal (UdM), Montréal H3C 3J7, Canada

    • Sherief Essa
    •  & Michel Lafleur
  5. Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer (IRIC), University of Montréal, Montréal H3T 1J4, Canada

    • Louis Gaboury
  6. Faculty of Dentistry, McGill University, Montréal H3A 1G1, Canada

    • Maryam Tabrizian
  7. Department of Oncology, Segal Cancer Centre, Jewish General Hospital, McGill University, Montréal H3T 1E2, Canada

    • Té Vuong
    •  & Gerald Batist
  8. Departments of Biochemistry, Medicine and Oncology, Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montréal H3A 1A3, Canada

    • Nicole Beauchemin


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S.M. acted as principal investigator, wrote the paper with assistance from O.F., M.M., D.R., S.T. and N.B. and developed the general principles and methods. G.B. and T.V. provided clinical insights. O.F., M.M., S.T., Y.Z.X., D.d.-L., D.L. and D.H. performed the experiments with tumour-bearing animals. S.J., Y.Z.X. and D.H. carried out the IV injections, processed all blood and tissues for analysis and analysed the samples. L.G. performed immunohistochemistry, immunofluorescence and histopathological evaluations. N.K. and M.M., assisted by M.A., acted as project managers. M.M. and O.F. performed the experiments for the preliminary in vivo proofs of concept. O.F. designed the experimental platform. D.d.-L. tested the magnetotactic control process, which was executed by D.L. M.L. and S.E. synthesized the liposomes. M.T. and S.T. attached the liposomes to the MC-1 cells. M.M. cultivated and prepared the bacteria for injection. M.M., D.R., G.B., L.G., N.B. and S.M. made revisions to the manuscript and figures. Y.Z.X. and D.H. coordinated the implantations of tumour xenografts. D.L. developed and calibrated the MC-1 counting software.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Sylvain Martel.

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