Mechanical and structural properties of rat and human lymphocytes after the exposure of the whole blood to X-rays in vitro

Abstract

Objective. By the means of atomic force microscopy to determine the changes in the parameters of the structural and mechanical properties of peripheral blood lymphocytes induced by the irradiation of whole blood by X-rays and identifying the possibility of assessing a state and radiation-induced lymphocyte death programs by analyzing a set of such parameters.Materials and methods. Whole blood of rats and humans was irradiated with X-rays (1–100 Gy) in vitro. Lymphocytes were isolated from the blood after a day of storage, placed on glass slides, fixed with glutaraldehyde and dried. The study of structural and mechanical properties was carried out with the help of atomic force microscope Bruker Bioscope Resolve in Peak Force QNM mode in air. For the sets of AFM parameters, which included elastic modulus, adhesion force, cell surface roughness and cell sizes, a k-mean clustering of data was carried out for the studied experimental groups.Results. The X-ray irradiation of the blood caused changes in the structural and mechanical properties of lymphocytes measured by AFM at the nanoscale. Clustering analysis of the sets of AFM parameters revealed clusters with similar structure in each experimental group (humans, 6and 16-month rats). The studied four clusters were associated with cell states and cell death programs: non-activated cells, activated cells with increased stiffness, apoptotic cells with reduced stiffness, and cells dying via programs other than apoptotic ones with increased stiffness. Each cluster (cell type) with a specific set of AFM parameters was represented differently in the blood lymphocyte population, depending on the dose of X-rays.Conclusion. The set of ACM parameters of lymphocytes including elastic modulus, adhesion force, roughness, and cell sizes, can be helpful for automatically determining the state and death program of lymphocytes after the local irradiation of humans with the involvement of peripheral blood (for example, after radio-therapeutic causes).