Affiliations: First Department of Medicine, Division of Cardiology, University of Pecs School of Medicine, Pecs, Hungary | Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
Note: [] Corresponding author: Dr. Herbert J. Meiselman, Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, 1333 San Pablo Street, MMR 626, Los Angeles, CA 90033, USA. Tel.: + 323 442 1268; Fax: + 323 442 2283; E‐mail: meiselma@usc.edu.
Abstract: Previous reports have suggested that non‐ionic poloxamer surfactants of appropriate molecular mass and composition can reduce red blood cell (RBC) aggregation in whole blood and in RBC‐plasma suspensions. We have thus evaluated this phenomenon for RBC aggregated by several water‐soluble polymers, using poloxamer 188 (P188), a non‐ionic, tri‐block molecule (total molecular mass of 8.40 kDa, 80% polyoxyethylene). Human RBC were washed, then re‐suspended in isotonic solutions of dextran 70 (70.3 kDa), dextran 500 (476 kDa), PVP (360 kDa) or P‐L‐GLU (61.2 kDa); density‐separated RBC were also studied. RBC aggregation was quantitated via a computerized Myrenne Aggregometer (extent, strength) and by the Microscopic Aggregation Index (MAI) method. Over the range of 0.5 to 5 mg/ml, poloxamer 188 inhibited both the extent and strength of aggregation in a dose‐dependent manner, with the magnitude of the decrease related to polymer type (e.g., at 5 mg/ml, 62% decrease for dextran 70 vs. 14% decrease for P‐L‐GLU); MAI results with dextran 70 also showed a dose‐dependent decrease. Poloxamer 188 at 5 mg/ml was more effective with younger, less‐dense cells. Based upon the depletion model for polymer‐induced aggregation, these findings suggest that poloxamer 188 acts by penetrating the depletion layer near the glycocalyx, thereby reducing the osmotic gradient between the intercellular gap and the suspending medium. Regardless of the specific mechanism(s) of action, poloxamers appear to offer interesting approaches for future basic science and clinical studies, and thus the possibility for greater insight into RBC aggregation.
Journal: Biorheology, vol. 37, no. 4, pp. 301-312, 2000
