Cell Microrheology

Posted on February 23, 2011 by admin

The red blood cell (RBC) deformability in microvasculature governs the cell’s ability to transport oxygen in the body. Interestingly, RBCs must pass periodically a deformability test by being forced to squeeze through narrow passages (sinuses) in the spleen; upon failing this mechanical assessment, the cell is destroyed and removed from circulation by macrophages (a type of white cell). Thus, understanding the microrheology of RBCs is highly interesting both from a basic science and clinical practice point of view. We present new quantitative optical measurements of RBC fluctuations obtained by highly sensitive diffraction phase microscopy (DPM). These spatio-temporal fluctuations are modeled in terms of the bulk viscoelastic response of the cell, which carries the spirit of the passive microrheology. Relating the displacement distribution to the storage and loss moduli of the bulk has the advantage of incorporating all geometric and cortical effects into a single effective medium behavior. Essentially, we treat the cell as a viscoelastic droplet that recovers the 3D shear behavior of the cell as it exhibits itself in flow.