Erythrocyte stiffness probed using atomic force microscope.

The stiffness of erythrocytes in patients (N=45) suffering from certain disorders, such as coronary disease, hypertension, and diabetes mellitus has been assessed using the Atomic Force Microscopy (AFM) and compared with that in a group of healthy individuals (N=13). For each blood sample, around 20 erythrocytes were selected at random and the stiffness of each one was probed in 20-30 arbitrarily chosen points. From these results, distributions of the cell Young's modulus (YM) were determined. Average values and widths of YM distributions significantly increased in samples taken from diabetes mellitus patients and cigarette smokers, as compared to those taken from healthy donors. At the same time, the average values of YM were found to increase as a function of the patient's age. We demonstrated that the atomic force microscope is a very sensitive tool for determination of cell stiffness with every prospect of a routine application as a diagnostic tool in quantitative analysis of the physiological and pathological states of red blood cells.