- Lindsey Osimiri
- Christian Landeros
- Team Blue
Title of Proposed Project
20.109(F12) Pre-Proposal: Inducing Apoptosis with Sound
Inducible apoptosis is a promising pathway for developing bacterial systems capable of drug delivery, but current research is limited to chemical or heat induction systems, both of which could be harmful or difficult to administer to patients undergoing treatment. Our group seeks to develop an engineered bacterial system capable of causing apoptosis in bacteria which responds to sound vibrations that can be administered from a distance. This research hopes to make bacterial drug delivery systems more accessible for patients, and could have greater implications in laboratory applications like recombinant protein production.
Inducible apoptosis is a topic that has been studied through several different avenues, notably in eukaryotes through gene therapy, or in bacteria with engineered pathways applying to drug delivery and recombinant protein production . Various studies by Di Stasi et al. and Pasotti et al. discovered that inducible apoptosis can be extremely useful in laboratory and medical applications. Di Stasi et al. demonstrated that cell death can be induced by insertion of a suicide gene, which allowed the group to deliver drugs effectively and in a controlled manner to combat cancer; Pasotti et al. found that inducible promoters can be used to effectively achieve apoptosis through a variety of mechanisms, implying that the apoptotic pathway is a good target for system engineering. Apoptosis has been achieved through several mechanisms like cell lysis, endonuclease production, or production of anti-microbial peptides. Though inducible apoptosis has been studied by many, the effects of sound on bacteria are poorly characterized. Sound has been shown to kill bacteria through sonication (thereby inducing lysis), and also without contact using ultrasound, but little work has been done in using a sound input in an engineered system to initiate programmed cell death. Our group believes that this technique would be extremely useful in medical applications, as it would avoid the complications associated with the use of additional drugs, and sound could be administered very simply to patients undergoing treatment with engineered bacterial drug delivery systems.
 Di Stasi A, Tey SK, Dotti G, Fujita Y, Kennedy-Nasser A, Martinez C, Straathof K, Liu E, Durett AG, Grilley B, Liu H, Cruz CR, Savoldo B, Gee AP, Schindler J, Krance RA, Heslop HE, Spencer DM, Rooney CM, Brenner MK. Inducible apoptosis as a safety switch for adoptive cell therapy. N Engl J Med. 2011;365:1673–1683
 Pasotti L, Zucca S, Lupotto M, Cusella de Angelis MG, Magni P. Characterization of a synthetic bacterial self-destruction device for programmed cell death and for recombinant proteins release. J Biol Eng. 2011;5:8
 Cho J, Hwang IS, Choi H, Hwang JH, Hwang JS, Lee DG. The Novel Biological Action of Antimicrobial Peptides via Apoptosis Induction. J Microbiol Biotechnol. 2012 Nov;22(11):1457-66
 Hoover K, Bhardwaj M, Ostiguy N, Thompson O. Destruction of bacterial spores by phenomenally high efficiency non-contact ultrasonic transducers. Mat Res Innovat 2002; 6:291-295
Little to no research has been published on the use of sound as a non-invasive, non-chemical, external approach to promote apoptosis in drug-delivering bacterial systems. Our group believes that the advantages of sound induction over drug-dependent induction are numerous, especially when considering the possibility of unwanted interaction with other therapeutic drugs used in patient treatment, as well as the long development process for creating successful chemical drug delivery methods. Our group seeks to develop a pathway for programmed cell death that can be induced by sound even after it has traveled through a medium (the body, air), which will make the system well-suited for applications to medicine and other industry purposes. A novel application would be to tumor-sensing, therapeutic bacteria that preferentially localize to the hypoxic tumor environment when introduced to the bloodstream. In this application, bacterial lysis would allow the release of therapeutic drugs directly to the tumor, and use of our system would allow an externally applied sound input near the tumor area to induce drug release at precisely determined time points.
Our experimental approach would begin at the computational design level, by engineering a sound-activated sensor, an apoptosis-initiating response system, and a connection between the input and output using previously characterized pathway components, like BioBrick devices. The complete system would then be expressed in a plasmid and optimized for expression in multiple prokaryotes. Mutations are commonly found in bacterial systems, so we would also study the effects of our system in bacterial strains with different vulnerabilities to mutation. The next objective will be to fine tune the response and dynamics of the system to optimize the practicality of our system. This will include extensive testing of sensitivity to different sound decibel and frequency levels, and the effects of medium composition and thickness on sound propagation and system response.
Illustration of proposed system to induce cell death with sound waves