Laser-assisted optical rotational cell analyzer measurements reveal early changes in human RBC deformability induced by photodynamic treatment.
BACKGROUND
The ability to deform is important for circulating RBCs in vivo, and earlier studies showed that this property can objectively be measured in vitro by the LORCA. In this study it was investigated whether photodynamic treatment of human RBCs (meant to inactivate contaminating pathogens) affects deformability.


METHODS
WBC-reduced RBC suspensions (30% Hct) were treated with 1,9-dimethylmethylene blue (DMMB) and red light. Changes in deformability were analyzed by LORCA measurements, in which elongation of the cells is measured at increasing shear stress. The effect of DMMB concentration and light dose was determined as well as the interfering effect of two scavengers of reactive oxygen species, that is, dipyridamole and Trolox.


RESULTS
Photodynamic treatment with DMMB resulted in clear changes in RBC deformability. Deformability changes occurred before onset of hemolysis. Under relatively mild treatment conditions, especially deformability at low shear stress was decreased, whereas deformability changes at high shear stress only occurred under harsher treatment conditions. Inclusion of dipyridamole and/or Trolox primarily prevented deformability changes at high shear stress.


CONCLUSIONS
LORCA measurements can effectively be used to detect changes in deformability that are induced by photodynamic treatment of human RBCs. A change in deformability represents an early marker of RBC damage under these conditions.
Hardeman
Max R
MR
Department of Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Besselink
Geert A J
GA
Ebbing
Iwan
I
de Korte
Dirk
D
Ince
Can
C
Verhoeven
Arthur J
AJ
D000975:Antioxidants / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology; D004176:Dipyridamole / Q000494:pharmacology; D004907:Erythrocyte Deformability / Q000187:drug effects*; D006801:Humans; D007834:Lasers; D008751:Methylene Blue / Q000031:analogs & derivatives* / Q000494:pharmacology*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*
D000975:Antioxidants; D002839:Chromans; D017319:Photosensitizing Agents; C435946:dimethylmethylene blue; D004176:Dipyridamole; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D008751:Methylene Blue