Interpretation of shifts in the values ​​of some indices of cytome analysis of buccal epithelial cells

Introduction. Accounting for micronuclei (MN) in the epithelium of the buccal mucosa is widely used to identify human exposure to genotoxic factors. Cytome analysis makes the test more sensitive to detect exposure, but it remains difficult to attribute changes in individual indices to toxicity or genotoxicity. We hypothesized that analysis of the frequencies of different forms of nuclear abnormalities in cells of different degrees of maturity could promote our understanding of the biological meaning of shifts in these indicators.

Materials and methods. A cytome analysis was carried out taking into account the degree of maturity of epithelial cells in scrapings of the cheek mucosa in 6–7 years children, and, for comparison, in the urothelium of mice and rats in the control and after the administration of a cystitis inducer and the standard mutagen cyclophosphamide (CP).

Results. In scrapings of the buccal mucosa from children, the frequency of cells with condensed chromatin in the nucleus, karyorrhexis and karyopyknosis increased significantly in intermediate cells, and the frequency of binuclear cells (BN), cells with nuclear buds (NB) and karyolysis increased only upon reaching a terminally differentiated state. Analysis of suspension preparations of the bladder epithelium in laboratory animals confirmed the predominant accumulation of BN in the superficial layers. In a model of cystitis in rats caused by a single administration of CP at a dose of 30 mg/kg, a decrease in the frequency of BN was observed at the end of the proliferative phase of post-traumatic epithelial regeneration (14 days after CP administration). After feeding mice with CP at a dose of 1.3 mg/kg/day for 14 days, an increase in the frequency of BN was noted among the most mature cells.

Limitation of the study is the lack of assessment of the DNA content in the nuclei of epithelial cells, which did not allow evaluating forms of polyploidy other than abortive cytokinesis (endocycling and endomitosis).

Conclusion. There was received confirmation of the relevance of interpretation the increase in the frequency of BNs in buccal epithelial cells in a group of exposed people as a manifestation of genotoxic effects; a decrease in the frequency of BNs in some cases may be associated with post-traumatic regeneration of the epithelium.

Compliance with ethical standards. The examination of children (sampling of desquamated buccal epithelium was carried out using a non-invasive method) in compliance with the norms and regulations enshrined in the Declaration of Helsinki of the World Medical Organization with the permission and in the presence of parents who filled out a voluntary informed consent form for the examination of their children. The study carried out under the European Convention for the Protection of Vertebrate Animals Used for Experiments or Other Scientific Purposes (ETS N 123), Directive of the European Parliament and Council of the European Union 2010/63/EU of 22.09.2010 on the protection of animals used for scientific purposes.

Contribution:
Yurchenko V.V. — analysis and interpretation of literature data, sampling of epithelial cells, preparation of preparations for cytome analysis, statistical analysis and description of the results of cytome analysis, writing an article;
Akhaltseva L.V. — search and analysis of literature data, microscopic analysis of smears of the mucous membrane of children, manuscript editing and preparing for publication;
Krivtsova E.K. — microscopic analysis of suspension preparations of the bladder of mice and rats;
Ingel F.I. — discussion and editing of the manuscript.
All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version.

Conflict of interest. The authors declare no conflict of interest.

Acknowledgment. The work was carried out within the framework of the state assignment “Analysis of adaptation changes in the population living in areas where odor sources are located, with the aim of developing recommendations for health authorities on managing the risk of environmentally related diseases”.

Received: July 5, 2024 / Accepted: October 2, 2024 / Published: November 19, 2024