Hacking bacteria to fight cancer - Tal Danino
-
0:06 - 0:11In 1884, a patient’s luck seemed
to go from bad to worse. -
0:11 - 0:14This patient had a rapidly growing
cancer in his neck, -
0:14 - 0:19and then came down with an unrelated
bacterial skin infection. -
0:19 - 0:22But soon, something unexpected happened:
-
0:22 - 0:27as he recovered from the infection,
the cancer also began to recede. -
0:27 - 0:32When a physician named William Coley
tracked the patient down 7 years later, -
0:32 - 0:34no visible signs of the cancer remained.
-
0:34 - 0:37Coley believed something remarkable
was happening: -
0:37 - 0:41that the bacterial infection
had stimulated the patient’s immune system -
0:41 - 0:44to fight off the cancer.
-
0:44 - 0:47Coley’s fortunate discovery
led him to pioneer -
0:47 - 0:51the intentional injection of bacteria
to successfully treat cancer. -
0:51 - 0:56Over a century later, synthetic biologists
have found an even better way -
0:56 - 0:59to use these once unlikely allies—
-
0:59 - 1:04by programming them to safely
deliver drugs directly to tumors. -
1:04 - 1:08Cancer occurs when normal functions
of cells are altered, -
1:08 - 1:13causing them to rapidly multiply
and form growths called tumors. -
1:13 - 1:17Treatments like radiation, chemotherapy,
and immunotherapy -
1:17 - 1:20attempt to kill malignant cells,
but can affect the entire body -
1:20 - 1:23and disrupt healthy tissues
in the process. -
1:23 - 1:26However, some bacteria like E. coli
-
1:26 - 1:32have the unique advantage of being able
to selectively grow inside tumors. -
1:32 - 1:35In fact, the core of a tumor forms
an ideal environment -
1:35 - 1:39where they can safely multiply,
hidden from immune cells. -
1:39 - 1:41Instead of causing infection,
-
1:41 - 1:45bacteria can be reprogrammed
to carry cancer-fighting drugs, -
1:45 - 1:50acting as Trojan Horses
that target the tumor from within. -
1:50 - 1:55This idea of programming bacteria
to sense and respond in novel ways -
1:55 - 2:00is a major focus of a field called
Synthetic Biology. -
2:00 - 2:02But how can bacteria be programmed?
-
2:02 - 2:05The key lies in manipulating their DNA.
-
2:05 - 2:08By inserting particular genetic sequences
into bacteria, -
2:08 - 2:12they can be instructed
to synthesize different molecules, -
2:12 - 2:15including those
that disrupt cancer growth. -
2:15 - 2:18They can also be made
to behave in very specific ways -
2:18 - 2:21with the help of biological circuits.
-
2:21 - 2:25These program different behaviors
depending on the presence, absence, -
2:25 - 2:28or combination of certain factors.
-
2:28 - 2:32For example, tumors have low oxygen
and pH levels -
2:32 - 2:35and over-produce specific molecules.
-
2:35 - 2:39Synthetic biologists can program bacteria
to sense those conditions, -
2:39 - 2:44and by doing so, respond to tumors
while avoiding healthy tissue. -
2:44 - 2:46One type of biological circuit,
-
2:46 - 2:50known as a synchronized lysis circuit,
or SLC, -
2:50 - 2:53allows bacteria
to not only deliver medicine, -
2:53 - 2:56but to do so on a set schedule.
-
2:56 - 2:58First, to avoid harming healthy tissue,
-
2:58 - 3:02production of anti-cancer drugs
begins as bacteria grow, -
3:02 - 3:05which only happens
within the tumor itself. -
3:05 - 3:08Next, after they’ve produced the drugs,
-
3:08 - 3:11a kill-switch causes
the bacteria to burst -
3:11 - 3:14when they reach a critical population
threshold. -
3:14 - 3:18This both releases the medicine
and decreases the bacteria’s population. -
3:18 - 3:23However, a certain percentage
of the bacteria remain alive -
3:23 - 3:25to replenish the colony.
-
3:25 - 3:29Eventually their numbers grow large enough
to trigger the kill switch again, -
3:29 - 3:31and the cycle continues.
-
3:31 - 3:34This circuit can be fine-tuned
to deliver drugs -
3:34 - 3:38on whatever periodic schedule
is best to fight the cancer. -
3:38 - 3:42This approach has proven promising
in scientific trials using mice. -
3:42 - 3:47Not only were scientists able
to successfully eliminate lymphoma tumors -
3:47 - 3:48injected with bacteria,
-
3:48 - 3:51but the injection also stimulated
the immune system, -
3:51 - 3:56priming immune cells
to identify and attack untreated lymphomas -
3:56 - 3:58elsewhere in the mouse.
-
3:58 - 3:59Unlike many other therapies,
-
3:59 - 4:02bacteria don’t target a specific type
of cancer, -
4:02 - 4:08but rather the general characteristics
shared by all solid tumors. -
4:08 - 4:12Nor are programmable bacteria
limited to simply fighting cancer. -
4:12 - 4:15Instead, they can serve
as sophisticated sensors -
4:15 - 4:18that monitor sites of future disease.
-
4:18 - 4:22Safe probiotic bacteria could perhaps
lie dormant within our guts, -
4:22 - 4:25where they’d detect, prevent,
and treat disorders -
4:25 - 4:28before they have the chance
to cause symptoms. -
4:28 - 4:32Advances in technology
have created excitement around a future -
4:32 - 4:36of personalized medicine
driven by mechanical nanobots. -
4:36 - 4:38But thanks to billions of years
of evolution -
4:38 - 4:40we may already have a starting point
-
4:40 - 4:44in the unexpectedly biological
form of bacteria. -
4:44 - 4:47Add synthetic biology to the mix,
-
4:47 - 4:50and who knows what might soon be possible.
- Title:
- Hacking bacteria to fight cancer - Tal Danino
- Speaker:
- Tal Danino
- Description:
-
View full lesson: https://ed.ted.com/lessons/hacking-bacteria-to-fight-cancer-tal-danino
In 1884, an unlucky patient who had a rapidly growing cancer in his neck came down with an unrelated bacterial skin infection. As he recovered from the infection, the cancer surprisingly began to recede. The infection had stimulated the patient’s immune system. Today, synthetic biologists program bacteria to safely deliver drugs directly to tumors. How is this possible? Tal Danino investigates.
Lesson by Tal Danino, directed by Chris Bishop.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:51
lauren mcalpine edited English subtitles for Hacking bacteria to fight cancer | ||
Elise Haadsma approved English subtitles for Hacking bacteria to fight cancer | ||
Elise Haadsma accepted English subtitles for Hacking bacteria to fight cancer | ||
lauren mcalpine edited English subtitles for Hacking bacteria to fight cancer |