Two separate teams of scientists have this week published results of their research on detecting disease using genetically modified bacteria. A team in France, led by Jerome Bonnet of the University of Montpellier and involving the company Sys2Diag, used engineered bacteria to detect elevated glucose (a sign of diabetes) in the urine of human patients. Meanwhile, in the US, researchers led by Sangeeta Bhatia from Massachusetts Institute of Technology (MIT) and Jeff Hasty, from the University of California, San Diego, reprogrammed bacteria so that they would be visible in the urine of mice that had cancer. Both studies were published in the current edition of Science Translational Medicine.
Science magazine reports that the team in Montpellier added genetic circuitry to the bacteria so that they produced a large amount of a red fluorescent protein in the presence of a high concentration of glucose. The bacteria – a strain of E. coli – were then added to the human urine samples, where they produced a colour change. Science adds that for now this approach ‘isn’t any better than a standard glucose meter’ however because the detection scheme can be repurposed to detect other targets, ‘it could serve as a platform for a broad array of future diagnostics’.
The teams in the US were meanwhile focused on detecting cancer using urine samples from mice. The US teams engineered bacteria to produce a naturally occurring enzyme called LacZ when they encountered a tumour. They then injected mice with compounds that released light when they interacted with LacZ. So, the mice that had liver cancer produced LacZ which interacted with the compounds, turning the urine samples from yellow to red. Science adds, ‘What’s more, Bhatia and her colleagues report in the current issue of Science Translational Medicine this week, while conventional imaging techniques struggle to detect liver tumors smaller than 1 square centimeter, this approach was able to flag tumors as small as 1 square millimeter.’
The studies are certainly promising but there are several obstacles to be overcome before we see these methods being used on patients. For example, the researchers acknowledge the ethics of using genetically modified bacteria need to be discussed and explored further, according to the BBC. Also, speaking to Science, Jim Collins, a synthetic biologist at MIT cautioned that both approaches remain years away from being approved for clinical use.
In spite of these issues, the hope is that ultimately these advancements bring us one step closer to being able to cheaply and easily diagnose a range of diseases.
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Detection of pathological biomarkers in human clinical samples via amplifying genetic switches and logic gates