Dresden 2006 – scientific programme
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AKB: Biologische Physik
AKB 30: Poster Session I
AKB 30.29: Poster
Monday, March 27, 2006, 15:30–18:00, P1
Stress fluctuation and microrheology in endothelial cells — •Daniel Paranhos Zitterbart, Carina Raupach, and Ben Fabry — Zentrum für medizinische Physik und Technik, Henkestr. 91, 91052 Erlangen
Mechanical processes of living cells are controlled by cytoskeletal (CSK) dynamics, which can be measured from the motion of CSK-bound beads. Bead motion has been reported to follow a superdiffusive behavior that arise from ATP-driven intracellular stress fluctuations (e.g. polymerization processes and motor proteins) with a power spectrum Pu(ω) ∝ 1/ω2 (Lau et al, Phys Rev Lett 91:198101). Here we report direct measurements of force fluctuations that are transmitted to the extracellular matrix (ECM) by plating human vascular endothelial cells onto a collagen coated elastic polyacrylamide hydrogel. Force fluctuations were computed from gel deformations that we obtained from the displacements of gel-embedded fluorescent beads. In addition, we measured CSK dynamics using fibronectin coated fluorescent beads that were bound to the cell via integrin receptors. Bead motion of both CSK-bound and ECM-bound beads were expressed as mean square displacement (MSD) and showed a superdiffusive behavior that was well described by a power law: MSD = a · tb. Surprisingly, we found the same exponent b of 1.6 for both CSK-bound and ECM-bound beads. This finding suggests that the spontaneous motion of CSK-bound beads is driven by stress fluctuations with a 1/ωb+1 power spectrum, and that CSK dynamics and CSK stress fluctuations are closely coupled.