Polymicroviscometry (PMV) and erythrocyte aggregation

Abstract

The process of red blood cell (RBC) aggregation is always associated with its counterpart: phase separation. The possibility of predicting the occurrence of a specific hemodynamic effect produced by these two processes in the living vasculature is frequently limited by insufficient information on the extremely complex set of local flow conditions.

Polymicroviscometry (PMV) is a microrheological method which obviates the effects of phase separation by analyzing the flow behavior of closely packed RBC (Hct 0.80) through relatively thick (200–400 µm) porous media of non-restrictive geometry.

In presence of aggregating macromolecules, PMV discloses immediately the consequences of abnormal interactions between individual RBC, such as typically occurring in “compaction stasis” following from the “reversal of the Fahraeus effect” (Schmid-Schönbein). These are not correlating with the conventionally assessed values of RBC sedimentation rate (ESR).

PMV results obtained in the absence of aggregating macromolecules depend on the RBC ability to perform the movement of membrane tanktreading and correlate with the RBC life span in the circulation and with the extent of their splenic sequestration.

The rheological consequence of an abnormal RBC “deformability” is basically opposed to that of an abnormal propensity of RBC to aggregate. The overall microrheological manifestation of the association of both abnormalities can directly be assessed by PMV; the method might, therefore, be of interest for in vitro and/or extra-vivum pharmacological studies.