Differences in bead-milling-induced hemolysis of red blood cells due to shape and size of oscillating bead.

BACKGROUND: Red blood cell (RBC) susceptibility to hemolysis - or fragility - can be profiled by subjecting a sample to progressive durations of mechanical stress and measuring hemolysis upon each. The ability to control stress application with multiple variable parameters can be useful in various areas of research. Bead milling, by oscillating an object in a blood sample, can offer control of parameters including oscillation force and frequency. OBJECTIVE: This work addresses the role of bead shape and size, for a given container, in potentially creating qualitatively as well as quantitatively different fluidic stresses in the sample. METHODS: Identical, diluted RBC samples were stressed via bead milling using different beads, with other parameters the same. Resulting hemolysis was plotted for several time increments in each case. RESULTS: For a cylindrical bead oscillating at a given frequency and force, bead length was a determinant of albumin's protective effect on RBC, as reflected by mechanical fragility. Compared to a sphere of same diameter, the protective effect was absent with shorter cylinders, whereas for longer ones it appeared enhanced. CONCLUSIONS: Bead milling based RBC fragility testing could present a useful tool for creating, and studying effects of different shear stress types in inducing hemolysis.

An approach to measuring RBC haemolysis and profiling RBC mechanical fragility.

Red blood cells (RBC) can be damaged by medical products, from storage or from disease. Haemolysis (cell rupture and haemoglobin release) is often a key indicator, with mechanical fragility (MF) offering the potential to assess sub-haemolytic damage as well. This article reports on a unique approach to measuring haemolysis, without the need for centrifugation or other sample separation. It also reports on employing that in measuring blood fragility (susceptibility to haemolysis) under shear stress, utilising an electromagnet to cause a bead to oscillate within a cartridge that contains the sample. Cycling between stressing and optical measurement of induced haemolysis at progressively increasing durations of stress provides a fragility profile. Sub-system-level testing shows high accuracy for the haemolysis measurements and fair consistency for MF profiling. Improving accuracy and precision of profiling is a current focus and a fully integrated and automated version of this system is under development.