MOSCOW, 4 Jul. A new optical label that makes it possible to label individual cells without changing their genome has been developed by scientists from the Saratov National Research State University named after N.G. Chernyshevsky (SSU). According to the researchers, the invention will make it possible to observe their behavior in the cell population in almost any laboratory and will be widely used in medicine for the treatment of dementia, strokes, Alzheimer's disease and many tumors. The results are published in the Journal of biophotonics.
Observation of cell behavior is widely used in the diagnosis and treatment of various diseases. For example, in personalized medicine, living cells are taken from a patient's tissues, processed, and returned to the body to treat neurodegenerative diseases (dementia, strokes, Alzheimer's and Parkinson's), and many tumors, university scientists said.
Currently, changes in individual cells or their collective behavior are monitored using fluorescence — the emission of light by certain chemical structures under the external influence of a lamp or laser.
Employees of SSU named after N.G. Chernyshevsky, with the participation of the Skolkovo Institute of Science and Technology, have developed a new non-protein label for the study of cellular processes. According to scientists, it does not require interventions in the genome, retains its properties better and allows research to be carried out in almost any laboratory. to carry out long-term tracking of individual labeled cells in the population,» said Polina Demina, senior researcher at the laboratory «Remotely controlled systems for theranostics» of the Scientific Medical Center of SSU.
She explained that the proposed label is based on the dye rhodamine B, which is able to irreversibly change its color under the influence of intense laser radiation. By itself, the dye freely «sticks» to the cell membrane and can make all nearby cells glow. In order for it to localize only on the desired cells, rhodamine B was placed in polymer microcontainers.
«Our label is a solid particle with physical dimensions that allow free visualization of the selected object using both conventional and fluorescence microscopy» , – added Demina.
According to her, before exposure to light, rhodamine B fluoresces in the orange range and has a bright pink color, and after exposure to a laser, the color changes and the spectrum shifts to the green region. Therefore, cells with a «switched» label are easily separated from those that were not irradiated.
To «switch» the color of fluorescence, cells can be exposed to a 532 nm laser, which is often used in all molecular biology and medical laboratories for analysis. This makes the process of tracking labeled cells more accessible, the scientists said.
The scientists explained that the new technology is an alternative to the existing biological label. Now optical markers are being developed by creating transgenic cell lines and living organisms that produce fluorescent proteins.
«To make a cell glowing, you need to change its DNA using a plasmid or a virus, which will allow the cell to produce a special glowing protein. Thus, each daughter cell will carry a portion of foreign DNA,» said Demina.
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She emphasized that a plasmid or a virus can be integrated into any part of the cell genome, which can lead to disruption of cell functions.
Demina added that, depending on the structure of the protein label, it is necessary to select suitable, individual characteristics of the laser to excite the light signal of the molecule so that it has sufficient intensity. Over time, such a label «burns out» and its glow fades both due to degradation processes and cell division.
The proposed development does not have these shortcomings, the scientist noted. According to her, further research will give even more advantages of the new technology.
«At this stage, we are working on studying the mechanisms of photoconversion, its nature and photochemistry. Understanding this unique phenomenon will allow us to expand the range of dyes used and create multicolor cell labels» , – summed up Demina. » data->
This work was supported by the Russian Science Foundation (grant no. 22-23-00313). SSU is a participant of the State University Support Program «Priority 2030».