ABSTRACT
A critical review of various methods of testing of geroprotectors (antiaging compounds or physical factors) in experiments on cultured cells is presented. Some cytogerontological models (the Hayflick model, the stationary phase aging model, the cell kinetics model, and the colony-forming ability evaluation) are reviewed with a focus on general gerontological definitions (aging, death probability, survival curve, cell senescence, biomarkers of aging, aging and non-aging organisms, age-related diseases, etc.). The main attention has been paid to methodological aspects of geroprotectors research with these models. Problems arising when constructing survival curves for cultured cells in the stationary phase aging model are analyzed. In particular, consideration is given to some problems encountered when using the most widespread molecular probes designed for live/dead cell viability assays. In addition, the possible role of the growth medium acidification in the stationary phase aging phenomenon is reviewed. It is concluded that extracellular pH, which, by the way, is well correlated with intracellular pH, is very important but not the key factor determining survival of cells in a stationary culture. A note is made that the evaluation of colony-forming efficiency, though optimal for cell viability assessment, is unfortunately not applicable to postmitotic or very slowly propagating cells. Some questions regarding the interpretation of data obtained in such studies in application to humans are also considered. Popular approaches to choosing biomarkers of cell aging/senescence are briefly reviewed. It is assumed that the least number of problems associated with interpreting the results of testing potential geroprotectors in cytogerontological experiments arises when such studies are performed using normal human cells in the model of stationary phase aging, which is based on the concept of cell proliferation restriction as the main cause of accumulation of macromolecular lesions (mainly DNA damage) in cells of multicellular organisms with age that, in turn, leads to the aging (increase in the death probability) of the organisms. It is assumed that this theory answers almost all the listed questions to any universal concept of aging. However, in the authors’ opinion, even their approach will not give the final answer to the question of whether or not the studied factor is a geroprotector. The main conclusion is that gerontologists analyzing the possibilities for retarding or even blocking the aging process currently have no fully adequate alternative to the construction of survival curves for the cohorts of animals or humans, even though this approach is highly expensive and requires great labor expenditures. Apparently, all the cytogerontological models reviewed provide only preliminary testing of potential antiaging factors.
