Effects of dextran molecular weight on red blood cell aggregation

¹ School of Chemical and Biomedical Engineering, Nanyang Technological University
² Keck School of Medicine, University of Southern California

^* To whom correspondence should be addressed. E-mail: neu{at}ntu.edu.sg.

Submitted on February 5, 2008
Revised on April 11, 2008
Accepted on 9 June 2008

	Abstract

The reversible aggregation of human red blood cells (RBC) by proteins or polymers continues to be of biological and biophysical interest, yet the mechanistic details governing the process are still being explored. While a depletion model with osmotic attractive forces due to polymer depletion near the RBC surface has been proposed for aggregation by the neutral polyglucose dextran, its applicability at high molecular weights has not been established. In the present study RBC aggregation was measured over a wide range of dextran molecular weights (70 kDa to 28 MDa) at concentrations 2 g/dl. Our results indicate that aggregation does not monotonically increase with polymer size but rather demonstrates an optimum dextran molecular weight around 200-500 kDa. A model for depletion mediated RBC aggregation was employed to calculate the expected depletion energies. This model was found to be consistent with the experimental results and thus provides new insight into polymer-RBC interactions.

Key Words: dextran, erythrocyte, glycocalyx, polymer depletion