Background: In this study, we have investigated the viscoelastic behaviour of individual human adult bone marrow-derived mesenchymal stem cells (hMSCs) and the role of F-actin filaments in maintaining these properties, using micropipette aspiration technique together with a standard linear viscoelastic solid model.
Results: Under a room temperature of 20 degrees C, the instantaneous and equilibrium Young's modulus, E0 and Einfinity, were found to be 886 +/- 289 Pa and 372 +/- 125 Pa, respectively, while the apparent viscosity, mu, was 2710 +/- 1630 Pa.s. hMSCs treated with cytochalasin D up to 20 microM at 20 degrees C registered significant drop of up to 84% in stiffness and increase of up to 255% in viscosity. At the physiological temperature of 37 degrees C, E0 and Einfinity have decreased by 42-66% whereas mu has increased by 95%, compared to the control. Majority of the hMSCs behave as viscoelastic solid with a rapid initial increase in aspiration length and it gradually levels out with time. Three other types of non-typical viscoelastic behavior of hMSCs were also seen.
Conclusion: hMSCs behave as viscoelastic solid. Its viscoelstic behaviour are dependent on the structural integrity of the F-actin filaments and temperature.