A research group at the University of Waterloo is creating a groundbreaking method to combat cancer by engineering bacteria that can actually consume tumors from within.
“Bacteria spores enter the tumor, finding an environment where there are lots of nutrients and no oxygen, which this organism prefers, and so it starts eating those nutrients and growing in size,” said Dr. Marc Aucoin, a chemical engineering professor at Waterloo. “So, we are now colonizing that central space, and the bacterium is essentially ridding the body of the tumor.”
Central to this approach is a bacterium called Clostridium sporogenes, commonly found in soil, which thrives only in completely oxygen-free environments.
The core of a solid, cancerous tumor consists of dead cells and lacks oxygen, making it perfect for this bacterium to multiply.
However, there’s a biological challenge: when these tumor-eating organisms reach the outer edges of tumors, they encounter low levels of oxygen and die before fully eliminating them.
To tackle this issue, researchers first introduced a gene from a related bacterium into C. sporogenes that allows it to tolerate oxygen better. This helps it survive longer near the outer areas of targeted tumors.
They then figured out how to activate the oxygen-resistant gene precisely when needed – crucial for preventing bacteria from growing in places rich in oxygen like the bloodstream – by using a process known as quorum sensing.
In simple terms, quorum sensing involves chemical signals released by bacteria. Only when many bacteria have grown in a tumor is the signal strong enough to activate the oxygen-resistant gene, ensuring that it doesn’t happen prematurely.
In one study, researchers showed that Clostridium sporogenes could be modified to handle oxygen. In another study following that one, they tested their quorum sensing system by getting bacteria to produce a green fluorescent protein.
<p“Using synthetic biology, we built something like an electrical circuit, but instead of wires we used pieces of DNA,” said Dr. Brian Ingalls, a professor of applied mathematics at Waterloo. “Each piece has its job. When assembled correctly, they form a system that works in a predictable way.”
Researchers now plan to combine both the oxygen-resistant gene and quorum-sensing timing mechanism into one bacterium and evaluate it on tumors during pre-clinical trials.
This promising project emerged from work done by Ph D student Bahram Zargar under the guidance of Ingalls and Dr. Pu Chen, who is retired from his position as professor of chemical engineering at Waterloo. The work illustrates Waterloo’s commitment to interdisciplinary health innovation. Our engineers, mathematicians and life scientists are teaming up to create technology-driven solutions that turn discoveries into real-world care.
Waterloo researchers collaborated with the Center for Research on Environmental Microbiology (CREM Co Labs), which was co-founded by Dr. Zargar in Toronto. The team also includes Dr. Sara Sadr, who played a key role in this research effort.
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