News, Engineering an “Invisible Cloak” for Bacteria to Deliver Cancer Drugs

Columbia Engineering researchers report that they have developed a “cloaking” system that temporarily hides therapeutic bacteria from immune systems, enabling them to more effectively deliver drugs to tumors and kill cancer cells in mice. By manipulating the microbes’ DNA, they programmed gene circuits that control the bacteria surface, building a molecular “cloak” that encapsulates the bacteria.

“What’s really exciting about this work is that we are able to dynamically control the system,” said Tal Danino, associate professor of biomedical engineering, who co-led the study in collaboration with Kam Leong, Samuel H. Sheng Professor of Biomedical Engineering. “We can regulate the time that bacteria survive in human blood, and increase the maximum tolerable dose of bacteria. We also showed our system opens up a new bacteria delivery strategy in which we can inject bacteria to one accessible tumor, and have them controllably migrate to distal tumors such as metastases, cancer cells that spread to other parts of the body.”

For the study published today by Nature Biotechnology, the researchers focused on capsular polysaccharides (CAP), sugar polymers that coat bacterial surfaces. In nature, CAP helps many bacteria to protect themselves from attacks including immune systems. “We hijacked the CAP system of a probiotic E. coli strain Nissle 1917,” said Tetsuhiro Harimoto, a PhD student in Danino’s lab who is the study’s co-lead author. “With CAP, these bacteria can temporarily evade immune attack; without CAP, they lose their encapsulation protection and can be cleared out in the body. So we decided to try to build an effective on/off switch.”

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