Hacking bacteria to fight disease – Tal Danino

Hacking bacteria to fight disease – Tal Danino


In 1884, a patient’s luck seemed
to go from bad to worse. This patient had a rapidly
growing cancer in his neck, and then came down with an unrelated
bacterial skin infection. But soon, something unexpected happened: as he recovered from the infection,
the cancer also began to recede. When a physician named William Coley
tracked the patient down 7 years later, no visible signs of the cancer remained. Coley believed something
remarkable was happening: that the bacterial infection had
stimulated the patient’s immune system to fight off the cancer. Coley’s fortunate discovery
led him to pioneer the intentional injection of bacteria
to successfully treat cancer. Over a century later, synthetic biologists
have found an even better way to use these once unlikely allies— by programming them to safely
deliver drugs directly to tumors. Cancer occurs when normal functions
of cells are altered, causing them to rapidly multiply
and form growths called tumors. Treatments like radiation, chemotherapy,
and immunotherapy attempt to kill malignant cells,
but can affect the entire body and disrupt healthy tissues
in the process. However, some bacteria like E. coli have the unique advantage of being
able to selectively grow inside tumors. In fact, the core of a tumor forms
an ideal environment where they can safely multiply,
hidden from immune cells. Instead of causing infection, bacteria can be reprogrammed
to carry cancer-fighting drugs, acting as Trojan Horses that target
the tumor from within. This idea of programming bacteria
to sense and respond in novel ways is a major focus of a field
called Synthetic Biology. But how can bacteria be programmed? The key lies in manipulating their DNA. By inserting particular genetic
sequences into bacteria, they can be instructed to
synthesize different molecules, including those that disrupt
cancer growth. They can also be made to
behave in very specific ways with the help of biological circuits. These program different behaviors
depending on the presence, absence, or combination of certain factors. For example, tumors have low
oxygen and pH levels and over-produce specific molecules. Synthetic biologists can program
bacteria to sense those conditions, and by doing so, respond to tumors
while avoiding healthy tissue. One type of biological circuit, known
as a synchronized lysis circuit, or SLC, allows bacteria to not only deliver
medicine, but to do so on a set schedule. First, to avoid harming healthy tissue, production of anti-cancer drugs
begins as bacteria grow, which only happens within
the tumor itself. Next, after they’ve produced the drugs, a kill-switch causes the
bacteria to burst when they reach a critical
population threshold. This both releases the medicine
and decreases the bacteria’s population. However, a certain percentage of
the bacteria remain alive to replenish the colony. Eventually their numbers grow large
enough to trigger the kill switch again, and the cycle continues. This circuit can be fine-tuned to deliver
drugs on whatever periodic schedule is best to fight the cancer. This approach has proven promising
in scientific trials using mice. Not only were scientists able to
successfully eliminate lymphoma tumors injected with bacteria, but the injection
also stimulated the immune system, priming immune cells to identify
and attack untreated lymphomas elsewhere in the mouse. Unlike many other therapies, bacteria
don’t target a specific type of cancer, but rather the general characteristics
shared by all solid tumors. Nor are programmable bacteria
limited to simply fighting cancer. Instead, they can serve as
sophisticated sensors that monitor sites of future disease. Safe probiotic bacteria could
perhaps lie dormant within our guts, where they’d detect, prevent,
and treat disorders before they have the chance
to cause symptoms. Advances in technology have
created excitement around a future of personalized medicine driven
by mechanical nanobots. But thanks to billions of years
of evolution we may already have a starting point in the unexpectedly biological
form of bacteria. Add synthetic biology to the mix, and who knows what might soon be possible.

100 thoughts on “Hacking bacteria to fight disease – Tal Danino”

  1. 11 months too late, my best friend had already ascended to heaven. He died fighting through chemotherapy but the cancer managed to spread itself. Wish we had a better course of action.

  2. Can’t wait till the day where I’ll be telling a story about how my dad passed away from cancer as if that’s a crazy thing that most kids in the future wouldn’t understand

  3. Wouldn't this require that the "medication" be organic in nature? I've heard of CRSPR research but I haven't heard of it synthesizing new chemicals so I'm unclear on what would be delivered then regenerated.

  4. Note to doctors*
    I know this is going to sound crazy to you, but women aren’t the only ones who get cancer. There are also men who get cancer. Just for you to know. You know, just in case you think only women can get cancer.
    Moving on…

  5. Can’t wait for the time where saying that someone died from cancer is just like saying someone died from a strep throat nowadays..

  6. I've been watching these videos from past few years now. Still waiting for them to be publicly available. Chemotherapy is still the only treatment available on a large scale.

  7. They are experimenting with phage viruses to be use as cures for other diseases. Thus is due to the phages only attacking the certain bad bacteria and not all of the bacteria like antibiotics

  8. And after the bacteria wipes out the cancer cells, the programmed bacteria decides to stick around and multiply – just like rabbits in Australia.

  9. I had a similar one.. I had a pharyngitis and I developed a minor allergy towards nut, but when I got better, the nut allergy also disappeared.

  10. How could you alter the frequency at which the kill switch turns on? Could you control or programme the rate of bacterial division? Any other ways?

  11. i can see it now: an Actually Happened video with the title:
    I gave myself e coli to cure my cancer
    and then the video is about something completely different

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