Stanford Medicine researchers have made a groundbreaking discovery that could pave the way for innovative cancer treatments. By modifying the genomes of skin-dwelling microbes and bacteria, scientists have successfully used them to combat cancer in mice. When the altered microbes were applied to the mice’s fur, their tumors began to shrink.
The bacteria, Staphylococcus epidermidis, was collected from mice fur and engineered to produce a protein that stimulates the immune system to target specific tumors. The experiment showed great promise, with the modified bacteria effectively killing aggressive metastatic skin cancer without causing inflammation.
“It seemed almost like magic,” said Michael Fischbach, PhD, an associate professor of bioengineering at Stanford. “These mice had very aggressive tumors growing on their flank, and we gave them a gentle treatment where we simply took a swab of bacteria and rubbed it on the fur of their heads.”
This research delves into the largely unexplored world of microbiomes, which consist of numerous bacteria, fungi, and viruses. While gut biomes receive most of the attention, the skin also hosts countless microbes whose functions are often unknown.
In this case, scientists discovered that Staphylococcus epidermidis cells initiate the production of immune cells called CD8 T cells. The researchers essentially reprogrammed the S. epidermidis to produce CD8 T cells that target specific antigens related to skin cancer tumors. Upon encountering a matching tumor, these cells rapidly multiplied and either reduced or entirely eliminated the tumor mass.
“Watching those tumors disappear — especially at a site distant from where we applied the bacteria — was shocking,” Fischbach said. “It took us a while to believe it was happening.”
Despite the promising results, there are several caveats to consider. The experiments were only conducted on mice, and it is unclear whether the same treatment would be effective in humans. Stanford researchers are uncertain if S. epidermidis triggers a similar immune response in humans, and they may need to investigate other microbes for potential modification. Additionally, this treatment is designed for skin cancer tumors and applied topically; its efficacy in treating internal cancers remains to be seen.
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