Difference between revisions of "Team:SJTU-BioX-Shanghai/Story"

On the first day of blazing June, which happened to be the International Children’s Day, ECHO was brought up by Kairan Zhang. But at that time, ECHO has only one part, the acoustic reporter gene (arg). We found it extremely interesting since nowadays researchers often use fluorescent proteins or beta-galactosidase as reporters. But what if we develop a brand new reporting system that involves unique characteristics? Is it possible that we can use this to conquer an existing problem?

With this ultimate goal in mind, we go on brainstorming over and over again. And we came up with all these amazing ideas listed below.

• Detection of intestinal flora
• Pharmacological research
• Detection of metabolism

However, none of these listed above really struck us. Until one day, we came across an article the author has used the args on imaging in vivo using ultrasound. We immediately realized that the most suitable application and the biggest advantage of args is imaging in vivo and this is exactly the key point of diagnosis in modern medicine.

After connecting args with ultrasound, we did tons of research about human diseases and at last we chose colon cancer as our target disease for the multiple reasons. First, colon cancer has a high morbidity both in China and the rest of the world and its existing diagnosis method, colonoscopy, has limited accessibility for public due to its painful process and great expense. If a cheap, convenient and noninvasive screening method is developed, and is affordable for most people, there is a great possibility that the morbidity of colon cancer can decrease greatly.

Read more about background

Since we have decided the core of our project, we moved on to designing our systems. In brief, our microbe incorporates four independent modules listed below.

• CRC targeting module
• Ultrasonic Reporting module
• Suicide module
• Therapeutic module

With the combination of the four modules, we’ve constructed ECHO, a device that can target cancer cells, image the cancerous tissues using ultrasound and give a preliminary bio-treatment of CRC.

Read more about design.

This module enables bacteria to specifically adhere to CRC lesions in the lumen. To this end, ECHO is designed to display a CRC antigen binding moiety, a 15-aa oligo peptide, on its surface and can be anchored on the foci of CRC (design). A series of experiments were done to determine whether the cell surface display system (CSDS) correctly transports the oligo peptide to the outer membrane of the bacterium, as well as whether the oligo peptide are effective to build a cell-bacteria junction.It turned out the targeting module can bind to cancer cells with the average positive rate of 24.1% while that of the control group is only 2.9% (results). Moreover, in order to better suit ECHO to realistic application, we introduce young's modulus of bacteria to simulate the locomotion of bacteria in human colorectum and study its fluid mechanic behaviors (adhesion model).

Fig 1. T peptide anchoring the cancer cells.

When ECHO successfully binds to cancer cells, it is ready to image the cancerous tissues. The ultrasonic reporting module is prepared for the imaging. It contains a cluster of engineered gas vesicle proteins (ARG) that could form gas vesicles in the cytoplasm of E.coli. These bubbles are able to generate signals upon high-resolution ultrasonic inspection (design). We tested the function of ARGs by mixing cell cultures with gel and observed it through ultrasound. Furthermore, we injected the gel into mouse colon and observe under the same condition. The results show that the gas vesicles produced by ECHO can be detected both in vitro and in vivo using ultrasound and MRI (result). Since we would like ECHO be accessible to as many people as it can, we must make sure the gas vesicles ECHO produces could be detected using the most common ultrasound machine in clinical use. In order to realize this, we modeled the ultrasonic response of gas vesicles in our device and modify the key parameters by experimental results (model) .

Fig 2. ECHO detected by ultrasound.

When ECHO has gone through the above two stages, the diagnosis section is completed. Triggered by high level of nitric oxide near the cancerous tissues, ECHO will express an anticancer agent for a preliminary bio-treatment of CRC and release the agent by cell lysis. In wet lab, we induced the therapeutic module with sodium nitroprusside, the nitric oxide donors. The results showed the anticancer agent can be expressed by ECHO, indicating the nitric oxide sensor function normally (results). When it comes to the suicide module, in order to make sure ECHO lyses at the proper time, we introduced an attenuator to the gene circuit by model calculator (model).

Fig 3. Cell lyses to release the drug.

By now, we had got the ECHO tested both in vitro and in vivo. But it still needs a load to make it a real product. Since Tongji_China chose therapeutics as their track this year, so we both needs to look for a proper pharmaceutical preparation.Therefore, we collaborated to visit Roche, the world’s largest biotech company and also the global leader in cancer treatments, and their staff gave us advice on the choice of pharmaceutical preparations (interview).At last we have chosen two kinds of loader, the capsule and the hydrogel.(loader)

Fig 4. Taking ECHO orally.

Since ECHO was supposed to function in human body ultimately, our HP group focuses on finding the application prospect for our project. First, they take the biosafety of ECHO into account. By reading related literatures our HP group built a set of biosafety standards and assessed the biosafety level of ECHO. Second, we built a price-health model to estimate public’s acceptance of ECHO. Then, we analyzed ECHO’s rule in countries in different financial situations. At last, we walked into classes and campus to let more people learn about our engineered systems.(HP)