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Open Access Original investigation

Stiffness memory of EA.hy926 endothelial cells in response to chronic hyperglycemia

Marta Targosz-Korecka1, Grzegorz D Brzezinka1*, Katarzyna E Malek1, Ewa Stȩpień2 and Marek Szymonski1

Author Affiliations

1 Research Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland

2 Genetic Diagnostics and Nutrigenomic Unit, Department of Clinical Biochemistry, Jagiellonian University Medical College, Krakow, Poland

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Cardiovascular Diabetology 2013, 12:96  doi:10.1186/1475-2840-12-96

Published: 27 June 2013

Abstract

Background

Glycemic memory of endothelial cells is an effect of long-lasting hyperglycemia and is a cause of various diabetics complications, that arises despite of the treatment targeted towards returning low glucose level in blood system. On the other hand, endothelial dysfunction, which is believed to be a main cause of cardiovascular complications, is exhibited in the changes of mechanical properties of cells. Although formation of the glycemic memory was widely investigated, its impact on the mechanical properties of endothelial cells has not been studied yet.

Methods

In this study, nanoindentaion with a tip of an atomic force microscope was used to probe the long-term changes (through 26 passages, c.a. 80 days) in mechanical properties of EA.hy926 endothelial cells cultured in hyperglycemic conditions. As a complementary method, alterations in the structure of actin cytoskeleton were visualized by fluorescent staining of F-actin.

Results

We observed a gradual stiffening of the cells up to 20th passage for cells cultured in high glucose (25 mM). Fluorescence imaging has revealed that this behavior resulted from systematic remodeling of the actin cytoskeleton. In further passages, a drop in stiffness had occurred. The most interesting finding was recorded for cells transferred after 14 passages from high glucose to normal glucose conditions (5mM). After the transfer, the initial drop in stiffness was followed by a return of the cell stiffness to the value previously observed for cells cultured constantly in high glucose

Conclusions

Our results indicate that glycemic memory causes irreversible changes in stiffness of endothelial cells. The formation of the observed “stiffness memory” could be important in the context of vascular complications which develop despite the normalization of the glucose level.

Keywords:
Endothelial cells; Glycemic memory; Cell stiffness; Atomic force microscope; Hyperglycemia; Cardiovascular complications