It is commonly known that alteration of erythrocyte deformability lead to serious microcirculatory diseases such as retinopathy, nephropathy, etc. Various methods and technologies have been developed to diagnose such membrane properties of erythrocytes. In this study, we developed an innovative method to measure hemorheological characteristics of the erythrocyte membrane using a light scattering analysis with simplified optic setting and multi-cell analysis as well. Light scattering intensity through multiple erythrocytes and its power density spectrum were obtained. The results of light scattering analyses were compared in healthy control and artificially hardened sample which was treated with glutaraldehyde. These results were further compared with conventional assays to measure deformable property in hemorheology. We found that light scattering information would reflect the disturbance of membrane fluctuation in artificially damaged erythrocytes. Therefore, measuring fluctuation of erythrocyte membrane using light scattering signal could facilitate simple and precise diagnose of pathological state on erythrocyte as well as related complications.
Light-transmission and light-backscattering methods are commonly used to determine red-blood-cell (RBC) aggregation. Even though the results reveal good correlations between the parameters that are measured by these two methods, the methods themselves yield quite different values. The objective of this research is to investigate and delineate the characteristics of the two optical methods. We measured RBC aggregation by using a newly developed microchip-based aggregometer. An orthogonal polarization technique, wherein multiple scattering causes polarized light to be depolarized and passed through an orthogonal polarizer, was applied to the backscattering method. Our results were also compared to those of conventional aggregometers [laser-assisted optical rotational cell analyzer (LORCA)], and revealed that the backscattering method yielded higher aggregation indices than the transmission method and LORCA. However, the backscattering method with orthogonal polarization yielded the same values of aggregation indices as the transmission method. These agreements between the two methods were also found in measurements of RBC aggregability in various concentrations of dextran solutions.
Reduced deformability of red blood cells (RBCs) may play an important role on the pathogenesis of chronic vascular complications of diabetes mellitus. However, available techniques for measuring RBC deformability often require washing process after each measurement, which is not optimal for day-to-day clinical use at point of care. The objectives of the present study are to develop a device and to delineate the correlation of impaired RBC deformability with diabetic nephropathy. We developed a disposable ektacytometry to measure RBC deformability, which adopted a laser diffraction technique and slit rheometry. The essential features of this design are its simplicity (ease of operation and no moving parts) and a disposable element which is in contact with the blood sample. We studied adult diabetic patients divided into three groups according to diabetic complications. Group I comprised 57 diabetic patients with normal renal function. Group II comprised 26 diabetic patients with chronic renal failure (CRF). Group III consisted of 30 diabetic subjects with end-stage renal disease (ESRD) on hemodialysis. According to the renal function for the diabetic groups, matched non-diabetic groups were served as control. We found substantially impaired red blood cell deformability in those with normal renal function (group I) compared to non-diabetic control (P = 0.0005). As renal function decreases, an increased impairment in RBC deformability was found. Diabetic patients with chronic renal failure (group II) when compared to non-diabetic controls (CRF) had an apparently greater impairment in RBC deformability (P = 0.07). The non-diabetic cohort (CRF), on the other hand, manifested significant impairment in red blood cell deformability compared to healthy control (P = 0.0001). The newly developed slit ektacytometer can measure the RBC deformability with ease and accuracy. In addition, progressive impairment in cell deformability is associated with renal function loss in all patients regardless of the presence or absence of diabetes. In diabetic patients, early impairment in RBC deformability appears in patients with normal renal function.
The biological flow characteristics inside a rugged surface type microchannel are investigated experimentally using a micro-particle image velocimetry (micro-PIV) method. The main objectives of this study are to understand the blood flow structure inside a micro-domain blood vessel and to identify the feasibility of nano-scale fluorescent particles for velocity field measurement in a micron-sized channel. The flow field is analyzed with a spatial resolution of 1K×1K pixels at low Reynolds number flow. To obtain the spatial distributions of mean velocity, 100 instantaneous velocity fields are captured and ensemble-averaged. As a result, for the case of blood flow, there are substantial cell deformation and variations to pass through the rugged surface of a microchannel and the clear velocity vector field was acquired by using the present micro-PIV technique.
The laser-diffraction technique has been applied to design a microfluidic channel for measuring red blood cell deformability over a range of shear stress. A laser beam traverses a diluted blood suspension and is diffracted by RBCs in the volume. The diffraction patterns are captured by a CCD-video camera, linked to a frame grabber integrated with a computer. When deforming under decreasing shear stress in the microchannel, RBCs change gradually from the prolate ellipsoid towards a circular biconcave morphology. Both the laser-diffraction image and pressure were measured with respect to time, which enable to determine the elongation index (EI) and the shear stress. The range of shear stress is 0~20Pa and the measuring time is less than 2min. The elongation index (EI) is determined from an isointensity curve in the diffraction pattern using an ellipse-fitting program. The key advantage of this design is the incorporation of a disposable element that holds the blood sample, which enables the present system to be easily used in a clinical setting.
The laser-diffraction technique has been applied to design a slit rheometer for measuring red blood cell deformability over a range of shear stress. A laser beam traverses a diluted blood suspension and is diffracted by RBCs in the volume. The diffraction patterns are captured by a CCD-video camera, linked to a frame grabber integrated with a computer. When deforming under decreasing shear stress, RBCs change gradually from the prolate ellipsoid towards a circular biconcave morphology. Both the laser-diffraction image and pressure were measured with respect to time. Which enable to determine the elongation index (EI) and the shear stress. The range of shear stress is 0~35 Pa and the measuring time is less than 2 min. The elongation index (EI) is determined from an isointensity curve in the diffraction pattern using an ellipse-fitting program. The key advantage of this design is the incorporation of a disposable element that holds the blood sample, which enables the present system to be easily used in a clinical setting.