WikiLorrca – Lorrca – Functional RBC Analysis

WikiLorrca

The Laser Optical Rotational Red Cell Analyzer (Lorrca)

RR Mechatronics is the developer and manufacturer of the Laser-Optical Rotational Red Cell Analyzer (Lorrca), used for assessment of RBC functionality. The Lorrca has been developed in close collaboration with our science and technology partners. Scientists in over 20 countries use the Lorrca to contribute to research, often in research environments. Evaluation of the rheology of blood in different parts of the body is a very specific task, therefore it is important to have a technique available that can accurately measure the Red Blood Cell (RBC) properties. The unique Research Use Only instrument incorporates a variety of techniques to perform these specific measurements. The technique accurately detects RBC deformability as a function of shear stress, osmolality and oxygen pressure, which should be standard in the hematologic laboratory. Therefore, the Lorrca is not only vital in research, but also supportive in the clinical diagnostic fields.

The Lorrca instrument is appearing in hundreds of publications. The scope of the Lorrca’s capabilities is still growing. Besides the use in research, the clinical diagnostic fields become of great importance for the future.

Measurement RBC deformability is expressed as the Elongation Index (El) measured in quality controlled medium of known viscosity. A thin layer of RBC’s is sheared between two concentric cylinders and a certain, but exactly known, shear stress is applied to the cells (by rotation of the outer cylinder; the cup). The RBC’s will change, in an iso-osmotic environment, from oval biconcave disks to an elongated shape. The diffraction pattern produced by a laser beam can be measured. Deformability expressed as El can be measured as a function of Shear stress (Deformability test), Osmolality (Osmoscan test) or Oxygen pressure (Oxygenscan test).

Lorrca_Quick application Guide

Scheme

Osmoscan

The Osmoscan measures the deformability under an osmotic gradient. The Lorrca has the ability to automatically measure RBC deformability over a gradient of osmotic values. This results in a continuous curve; An Osmoscan test shows the cell’s condition at the different osmotic values. The test provides information about the cell’s deformability and membrane rigidity, depending on both the shape and the position along the osmolality axis. For this test 200 μl of whole blood is needed. With the Osmoscan, four parameters are defined:

Omin (osmolality at Elmin, hypotonic region),
Elmax (maximal El of the total curve),
Omax (osmolality at Elmax) and
Ohyper (osmolality corresponding to 50% of the Elmax; hypertonic region).

Video:
Lorrca osmoscan measurement

Video:
Measuring Deformability and Red Cell Heterogeneity in Blood by Ektacytometry

source: National Center for Biotechnology Information

Curve Osmocan

Deformability test

The capacity of RBC’s to deform is a powerful indicator of their viability as it is essential for the optimal circulation of these cells both in micro- and macro-circulation. This deformability depends on three important cell properties.

Surface area to volume ratio
Viscoelastic properties of the membrane
The viscosity of the intracellular fluid

Because of the osmotic variety of the medium (50-500 mOsm/kg) during the measurement, continuous deformation occurs which is measured by a laser beam diffraction pattern; captured with a video camera and analyzed by a computer. For this test only 25 μl of blood is needed.

Features:

Fast testing
High reproducibility and repeatability
Multiple research fields

Elongation

Aggregation and Dis-aggregation

RBC aggregation is an important, shear dependent, determinant of blood viscosity. Hyperaggregability can be detected in various diseases (e.g inflammatory states, vascular pathologies and tissue perfusion problems).

Measurement Complete disaggregation of the RBC’s is induced by applying a high shear rate; followed by an abrupt stop, which causes the elongated and orientated RBC to retake their normal, biconcave, shape and orientate randomly. Then the aggregation process starts, at which rouleaux formation occurs. A syllectogram is created by plotting the laser backscattered intensity (Isc) versus time. By means of a photodiode (which measures the change in light backscatter) the total extent and kinetics of aggregation are displayed, as well as the minimal shear rate (threshold) needed to prevent RBC aggregation, i.e. the tendency for aggregation. For this test ~1 ml of whole blood is needed.

Curve Syllectogram