Researchers employed the bacterium Clostridium sporogenes, a microorganism typically found in soil environments. This particular species can only thrive in environments completely devoid of oxygen. Large tumor cores fit this description perfectly, as they are often composed of necrotic (dead) cells and lack oxygen, establishing an ideal breeding ground for these bacteria. The findings of this research were detailed in a publication by ACS Publications.
The primary obstacle encountered was that as the bacteria multiplied and migrated towards the tumor’s periphery, they encountered areas with minimal oxygen, leading to their demise before the cancer could be entirely eradicated. To overcome this limitation, the scientists engineered the bacteria by inserting a gene designed to boost their tolerance to oxygen.
Nevertheless, merely rendering the bacteria oxygen-tolerant proved insufficient; precise control over this modification was essential. If the resistance mechanism were to activate prematurely, the bacteria could survive within the bloodstream or other healthy tissues, posing a significant risk to the patient. To achieve this fine-tuned regulation, the researchers leveraged a natural bacterial communication system known as quorum sensing.
Bacteria secrete chemical signaling molecules, and as their population size increases, this signal intensifies. The gene conferring oxygen resistance is triggered only when this signal hits a specific threshold, meaning a sufficient concentration of bacteria has amassed within the tumor. This ensures the survival mechanism initiates exclusively at the correct location and at the opportune moment. In laboratory trials, the researchers validated the system’s efficacy by programming the bacteria to produce a luminescent protein upon activation.
The subsequent phase of this project involves incorporating all the necessary genes into a single bacterial strain and proceeding with preclinical trials involving animal subjects.
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