Diagnosis in urine Artificial bacteria detect cancers

Researchers are developing bacteria to identify biomarkers of disease
Bacteria could help diagnose cancer and other diseases in the future. Because scientists succeeded in the artificial production of bacteria that can detect typical biomarkers of diseases such as diabetes. About the "Bactosensoren" report the researchers in the journal "Science Translational Medicine".

Bacteria detect biomarkers of diseases
A French research team integrated genetically modified Escherichia coli bacteria into a technical system so that signals can be identified that can be read by diagnostic equipment. For this, the bacteria have been embedded in hydrogel beads, as the researchers report to Alexis Courbet from the Sys2Diag network of the French research organization CNRS and the company Alcediag.

Artificial bacteria recognize cancer. (Image: Klaus Eppele / fotolia)

The bacteria worked very well in diabetes patients with elevated glucose levels in the urine sample. So they triggered a color change of the sample, which was due to a red fluorescent protein. The bactosensors are, according to the researchers, as reliable as conventional test strips. The approach may also be useful for identifying typical biomarkers of other diseases. However, at the moment the duration of the process is disadvantageous compared to other diagnostic procedures, because it takes 18 hours until a signal is measurable, write Courbet and his team.

"Biosensors are a large field of research in which a lot of money is invested," reports Torsten Waldminghaus from the Center for Synthetic Microbiology of the University of Marburg in an interview with the news agency "dpa". The results of the French research team could be seen as a test of the method. "It is not impressively impressive compared to conventional methods." According to Waldminghaus, a decisive advantage of biosensors is that they are very sensitive. This is difficult to construct while the production of the bacteria is easy. "They multiply themselves." This reduces the costs and allows large-scale operations, such as the detection of explosives on minefields.

Urine sample is sufficient bacteria to detect cancer
American researchers led by Tal Danino of the Massachusetts Institute of Technology (MIT) at Cambridge succeeded in producing artificial bacteria to detect liver metastases using a urine sample. Metastases in the liver, which are due to tumors in other organs, have a good prognosis, provided they are detected early. Unfortunately, in practice, they are often diagnosed late because imaging diagnostic methods often make it possible to detect metastases only at an advanced stage.

There are measures, such as local surgery or local ablation, that doctors can perform if the spread of the disease is limited to the liver. Because the liver is able to regenerate, these interventions are tolerable. New data show that these patients have a higher survival rate, which is why there is a particular need to diagnose metastases in the liver as early as possible, "explains Sangeeta Bhatia of MIT. If the metastasis is very large, an operation may not be possible or useful.

Probiotic bacteria can identify tumors
The MIT researchers also resorted to an E. coli strain as a source bacterium. They chose the probiotic E. coli Nissle 1917. This was genetically engineered to produce the enzyme beta-galactosidase, which cleaved an added substance to light-emitting molecules. These were easily detected in urine samples. In addition, the researchers knew that some types of bacteria prefer to multiply in cancerous tumors, as they provide food and protection against the immune system.

In experiments with mice that ate artificially modified E. coli bacteria with their food, it was found that the bacteria passed through the intestinal wall and colonized existing tumors in the liver. Other organs or healthy liver tissue, however, remained free from the altered probiotics. In the liver metastases, the bacteria then released the enzyme that cleaved the injected substance. As expected, a light-emitting molecule was formed which could be detected in the urine sample by red staining.

As the researchers report, the bacteria would also have been found to be very reliable in further testing for metastases from tumors of the gut, lung, ovaries or pancreas. No serious side effects of E. coli infection were observed in the year following the bacterial use in the mice. (Ag)