Micropipette methods for analysing blood cell rheology and their application to clinical research

Abstract

Micropipette methods can be used to investigate the mechanical and adhesive properties of blood cells. Although the procedures are generally technically demanding, unique information on the specific properties of individual cells can be determined, not readily available by other techniques. For red blood cells, the overall deformability (resistance to flow into ~3μm pipettes) can be tested, as well as more specific measurements of the contributing factors; cell geometry and membrane visco-elasticity. White blood cells and, rarely, platelets have also been subjected to analysis of their resistance to deformation. Cell-cell adhesion can be investigated, either by using two pipettes to bring cells together or by using a single pipette to manipulate a cell into contact with a coated, adhesive surface. Most measurements have centred on quantitation of the force required to disrupt adhesion. Such measurements allow insight into the factors which determine circulatory behaviour, and evaluation of the pathological changes which occur in circulatory disorders. In sickle cell disease and malaria, e.g., red cell deformability and geometry, membrane visco-elasticity and cell adhesiveness have all been investigated, while for leukocytes, the rheological effects of neutrophil activation, which may influence inflammatory and ischaemic processes, have been quantitated.