Affiliations: [a] Division of Bioengineering, Nanyang Technological University, Jurong West, Singapore | [b] Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, USA | [c] Department of Physiology and Biophysics, Keck School of Medicine, Los Angeles, CA, USA | [d] Faculty of Life Sciences, University of Applied Sciences Rhine-Waal, Kleve, Germany
Correspondence:
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Address for correspondence: Dr. Herbert J. Meiselman, Department of Physiology and Biophysics, Keck School of Medicine, 1333 San Pablo Street, McKibben 351, Los Angeles, CA 90033, USA. Tel.: +1 323 442 1268; Fax: +1 323 442 2283; E-mail: meiselma@usc.edu.
Abstract: Background:Cell–cell and cell–surface adhesion modulated by water-soluble polymers continues to be of current interest, especially since prior reports have indicated a role for depletion-mediated attractive forces. Objective:To determine the effects of concentration and molecular mass of the neutral polymer dextran (40 kDa to 28 MDa) on the adhesion of human red blood cells (RBC) to coated glass coverslips. Methods:Confocal-reflection interference contrast microscopy (C-IRM), in conjunction with phase contrast imaging, was utilized to measure the adhesion dynamics and contact mechanics of RBC during the initial stages of cell contact with several types of substrates. Results:Adhesion is markedly increased in the presence of dextran with a molecular mass ⩾ 70 kDa. This increased adhesiveness is attributed to reduced surface concentration of the large polymers and hence increased attractive forces due to depletion interaction. The equilibrium deformation of adhering RBC was modeled as a truncated sphere and the calculated adhesion energies were in close agreement with theoretical results. Conclusions:These results clearly demonstrate that polymer depletion can promote RBC adhesion to artificial surfaces and suggest that this phenomenon may play a role in other specific and non-specific cell–cell interactions, such as rouleau formation and RBC–endothelial cell adhesion.
