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Nature. 2016 Aug 4;536(7614):81-85. doi: 10.1038/nature18930. Epub 2016 Jul 20.

Synchronized cycles of bacterial lysis for in vivo delivery.

Author information

1
Department of Bioengineering, University of California, San Diego, La Jolla, California, USA.
2
Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA.
3
BioCircuits Institute, University of California, San Diego, La Jolla, California, USA.
4
Broad Institute of Harvard and MIT, Cambridge, MA.
5
Department of Medicine, Brigham and Women's Hospital, Boston, MA.
6
Electrical Engineering and Computer Science and David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA.
7
Howard Hughes Medical Institute, Chevy Chase, MD.
8
Molecular Biology Section, Division of Biological Science, University of California, San Diego, La Jolla, CA 92093, USA.
#
Contributed equally

Abstract

The widespread view of bacteria as strictly pathogenic has given way to an appreciation of the prevalence of some beneficial microbes within the human body. It is perhaps inevitable that some bacteria would evolve to preferentially grow in environments that harbor disease and thus provide a natural platform for the development of engineered therapies. Such therapies could benefit from bacteria that are programmed to limit bacterial growth while continually producing and releasing cytotoxic agents in situ. Here we engineer a clinically relevant bacterium to lyse synchronously ata threshold population density and to release genetically encoded cargo. Following quorum lysis, a small number of surviving bacteria reseed the growing population, thus leading to pulsatile delivery cycles. We used microfluidic devices to characterize the engineered lysis strain and we demonstrate its potential as a drug delivery platform via co-culture with human cancer cells in vitro. Asa proof of principle, we tracked the bacterial population dynamics in ectopic syngeneic colorectal tumours in mice via a luminescent reporter. The lysis strain exhibits pulsatile population dynamics in vivo, with mean bacterial luminescence that remained two orders of magnitude lower than an unmodified strain. Finally, guided by previous findings that certain bacteria can enhance the efficacy of standard therapies, we orally administered the lysis strain alone or in combination with a clinical chemotherapeutic to a syngeneic mouse transplantation model of hepatic colorectal metastases. We found that the combination of both circuit-engineered bacteria and chemotherapy leads to a notable reduction of tumour activity along with a marked survival benefit over either therapy alone.Our approach establishes a methodology for leveraging the tools of synthetic biology to exploit the natural propensity for certain bacteria to colonize disease sites.

PMID:
27437587
PMCID:
PMC5048415
DOI:
10.1038/nature18930
[Indexed for MEDLINE]
Free PMC Article

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