YongKeun Park
a, Catherine A. Best
b, Kamran Badizadegan
a,c, Ramachandra R. Dasari
a, Michael S. Feld
a, Tatiana Kuriabova
d, Mark L. Henle
e, Alex J. Levine
f,1, and Gabriel Popescu
a,g,1
aG. R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139;
bCollege of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
cDepartment of Pathology, Harvard Medical School and Massachusetts General Hospital, Boston, MA 02114;
dDepartment of Physics, University of Colorado, Boulder, CO 80309;
eSchool of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138;
fDepartment of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095; and
gQuantitative Light Imaging Laboratory, Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
Edited by Tom C. Lubensky, University of Pennsylvania, Philadelphia, PA, and approved February 26, 2010 (received for review August 23, 2009)
Abstract
The human red blood cell (RBC) membrane, a fluid lipid bilayer tethered to an elastic 2D spectrin network, provides the principal control of the cell’s morphology and mechanics. These properties, in turn, influence the ability of RBCs to transport oxygen in circulation. Current mechanical measurements of RBCs rely on external loads. Here we apply a noncontact optical interferometric technique to quantify the thermal fluctuations of RBC membranes with 3 nm accuracy over a broad range of spatial and temporal frequencies. Combining this technique with a new mathematical model describing RBC membrane undulations, we measure the mechanical changes of RBCs as they undergo a transition from the normal discoid shape to the abnormal echinocyte and spherical shapes. These measurements indicate that, coincident with this morphological transition, there is a significant increase in the membrane’s shear, area, and bending moduli. This mechanical transition can alter cell circulation and impede oxygen delivery.
membrane dynamics, microrheology, quantitative phase imaging
Footnotes
1To whom correspondence may be addressed.
Author contributions: Y.P., A.J.L., and G.P. designed research; Y.P. and C.A.B. performed research; C.A.B., K.B., R.R.D., M.S.F., and G.P. contributed new reagents/analytic tools; Y.P., T.K., M.H., A.J.L., and G.P. analyzed data; and Y.P., A.J.L., and G.P. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at
www.pnas.org/cgi/content/full/0909533107/DCSupplemental.
Freely available online through the PNAS open access option.