Cancer cells are different from normal cells and have particular abilities that cause them to produce volatile organic compounds (VOCs) that can act as biomarkers for cancer diagnosis when using gas chromatography or artificial olfactory systems.
But the results of gas chromatography analysis are extremely variable and ‘E-noses’ (artificial olfactory systems) are still to reach a viable prototype stage where a system that is cost-effective and accurate enough is on the horizon.
This is why the noses of animals like dogs are extremely well-suited for detecting the VOCs produced by cancerous cells and thereby, detecting cancer biomarkers. Dogs have evolved their olfactory senses over millions of years of evolution and have the ability to detect extremely faint odors as well as the brainpower to distinguish and determine between them.
But it takes months of training and conditioning before a dog can successfully distinguish between cancerous and non-cancerous cells and hundreds of time-consuming trials. For example, in one study it took two dogs, 5 months of training and 1,531 conditioning trials to perform 31 tests with 90.3% accuracy.
Armed with earlier evidence that insects could also use odor to detect cancer cells, researchers combined the use of ants with a ‘low-cost, easily transferable, behavioral analysis’ to create a bio-detector tool for cancer VOCs.
According to the research paper published in iScience, researchers submitted 36 individual F. fusca ants to three training trials where they were put in a circular arena where the odor of a human cancer cell sample was associated with a reward of sugar solution.
During these tests, ants spent significantly more time near the conditioned odor (cancer cells) than near the culture medium alone.
Over the trials, the time that the ants needed to find the reward decreased, indicating that they have been trained to detect the presence of cells based on their emittance of VOCs. This was confirmed by ants performing two consecutive memory tests with no reward present.
During the research, not only was it found that ants can distinguish between cancerous and non-cancerous cells, but they could also distinguish between cells from two different cancerous lines.
The short training time and the fact that ants can reproduce easily makes their use as bio-detectors for cancerous cells’ VOCs more viable than training and testing dogs or other larger animals with a great sense of smell.
Summarizing their findings, the authors state that “ants were able to i) perceive the presence of cells in a medium, ii) differentiate cancerous VOCs from non-cancerous ones, and iii) differentiate between two cancerous samples based on VOCs.”
“We show that individual ants need only a few training trials to learn, memorise, and reliably detect the odor of human cancer cells,” they added.
Whether or not ants can reliably diagnose cancer in actual patients will need to be examined in large-scale clinical trials. However, based on their observations, the study authors conclude that “using ants as living tools to detect biomarkers of human cancer is feasible, fast, and less laborious than using other animals.”
Source: iScience
