Use of RBC deformability index as an early marker of diabetic nephropathy

Red blood cell sedimentation rate measurements in a high aspect ratio microchannel

BACKGROUND

The erythrocyte sedimentation rate (ESR) test is commonly used in clinical practice for monitoring, screening and diagnosing pathological conditions and diseases related to the inflammatory response of the immune system. Several ESR techniques have been developed over the years improving the reliability, the precision and the duration of the measurement.

OBJECTIVE

In the present study a new low cost micro-ESR technique is described providing the major advantage of reducing the measurement time and the blood sample volume by multiple times compared to the commercial methods.

METHODS

Blood samples were obtained from healthy donors within the age group of 24-28 years and the haematocrit was adjusted to 30%, 40% and 50%. The ESR of the samples was measured utilizing a surface tension driven (STD) microfluidic chip and a monitoring device.

RESULTS

The evaluation of the method showed a high correlation (0.94, p < 10-5) at all haematocrit levels with the commercial instrument indicating the feasibility of the technique.

CONCLUSIONS

This micro-ESR technique provides the potential for a simple, low cost and fast tool for ESR measurement using low blood volume acquired by finger prick.

Probing Red Blood Cell Membrane Microviscosity Using Fluorescence Anisotropy Decay Curves of the Lipophilic Dye PKH26

Red blood cell (RBC) aggregation and deformation are governed by the molecular processes occurring on the membrane. Since several social important diseases are accompanied by alterations in RBC aggregation and deformability, it is important to develop a diagnostic parameter of RBC membrane structural integrity and stability. In this work, we propose membrane microviscosity assessed by time-resolved fluorescence anisotropy of the lipophilic PKH26 fluorescent probe as a diagnostic parameter. We measured the fluorescence decay curves of the PKH26 probe in the RBC membrane to establish the optimal parameters of the developed fluorescence assay. We observed a complex biphasic profile of the fluorescence anisotropy decay characterized by two correlation times corresponding to the rotational diffusion of free PKH26, and membrane-bounded molecules of the probe. The developed assay allowed us to estimate membrane microviscosity ηm in the range of 100-500 cP depending on the temperature, which paves the way for assessing RBC membrane properties in clinical applications as predictors of blood microrheological abnormalities.

Critical shear stress of red blood cells as a novel integrated biomarker for screening chronic kidney diseases in cases of type 2 diabetes

BACKGROUND:

The glomerular filtration rate (GFR) and albumin-to-creatinine ratio (ACR) have been widely used to identify and manage diabetic kidney disease (DKD). However, classifications based on these two indices do not always concur in terms of DKD diagnosis; for example, cases of high ACR with normal GFR or normal ACR with low GFR may occur. A recent study suggested that critical shear stress (CSS), a hemorheological parameter to represent aggregating force of red blood cells (RBCs), is a potential screening index for DKD. In the present study, we investigated the diagnostic potential of CSS for DKD according to the KDIGO 2012 Guideline.

METHODS:

A total of 378 patients with type 2 diabetes who visited Yeungnam University Hospital between 2014 and 2017 were included. CSS was measured using a transient microfluidic hemorheometer, Rheoscan-D300® (Rheomeditech, Seoul, Republic of Korea) with whole blood. Patients who were DKD negative (green zone) were compared with patients who were DKD positive (red zone) as Model 1 and patients at risk for (orange zone) and red zones as Model 2, respectively.

RESULTS:

After exclusion criteria such as eGFR < 30 mL/min/1.73 m², alcoholism, and macrovascular complications were applied, the sensitivity and specificity were 100% and 77.8% for Model 1 and 75.0% and 72.0% for Model 2, respectively. The diagnostic accuracy measures of the CSS for Model 1 were found to be highly accurate or have the potential to alter clinical decisions. Similarly, the diagnostic accuracy measures of CSS for Model 2 were found to provide useful information, despite them expanding to the orange and red zones.

CONCLUSION:

DKD was successfully identified using a novel integrated hemorheological index of CSS that satisfied both ACR and GFR criteria. Therefore, CSS may be useful for the additive diagnosis of DKD with GFR and uACR.

A New In Vitro Blood Hyperviscosity Model

We developed a model of blood hyperviscosity avoiding extreme impact on the blood. The model shows reproducibility in rat blood under common storage conditions (4±1°C; stabilization with citrate-phosphate-glucose additive solution). Storage of rat blood under these condition leads to impairment of its rheological properties, which manifested in an increase in blood viscosity in a wide range of shear rates (3-300 sec^-1). An increase in blood viscosity appeared the first day of storage and reached a maximum on the third day. During further 11-day storage, the blood viscosity did not change significantly. A hybrid macromolecular compound O-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoyl)-(1→6)-α-D-glucan improved the hemorheological properties during storage. The most pronounced effect was observed on the third day of storage and manifested in a decrease in blood viscosity in the range of shear rates of 50-300 sec^-1. Thus, storage of rat blood with citrate-phosphate-glucose additive solution for 3 days at 4±1°C reproduces the phenomenon of blood hyperviscosity; this model can be used to screen agents with hemorheological activity.

Use of haematological signatures in conjunction with conventional biomarkers to assess Reno-protective effects of Gedunin in diabetic nephropathy of Streptozotocin induced diabetic rats

Purpose

The present study was aimed at analysing the reno-protective potential of Gedunin (a limonoid from Neem leaves) through haematological and serological assays and renal histopathology studies in streptozotocin induced diabetic rats.

Method

Four weeks old Wister albino rats were chosen for the study. The rats were divided into four groups of 8 rats each. Group 1 (normal control rats); Group 2 (diabetic control rats); Group 3 (Drug control rats: normal rats treated with 1 mg/kg body weight of Gedunin thrice a week through oral gavage for 2 weeks); Group 4 (diabetic rats treated with Gedunin similar to Group 3). Diabetes was induced using a single intraperitoneal injection of streptozotocin (50 mg/kg) in the pre-determined groups. After completion of treatment, the rats were sacrificed and haematological and serological parameters including functional indices of blood cells and renal markers were evaluated through spectrophotometric methods. Renal histology studies were carried out and images were captured on Olympus SC 100, 10 Mega Pixel camera.

Results

Streptozotocin induced diabetes lead to marked reduction in the RBC count, haemoglobin, PCV, WBC count, lymphocyte, elevated levels of fasting blood glucose, kidney function markers such as urea, creatinine, uric acid in rats. Administration of Gedunin significantly (P < 0.05) ameliorated the elevated levels of fasting glucose, RDW%, MCHC%, NLR% and platelet count. A significant reversal of renal tissue damage was also observed.

Conclusion

The restoration of renal serological markers and reversal of renal tissue injuries are all indicative of promising reno-protective potential of Gedunin. Remarkable improvement of haematological parameters supports their use as reno-protection markers.

Erythrocyte Deformability and Na,K-ATPase Activity in Various Pathophysiological Situations and Their Protection by Selected Nutritional Antioxidants in Humans

The physicochemical and functional properties of erythrocytes are worsened in a variety of diseases. Erythrocyte deformability refers to their ability to adjust their shape according to external forces exerted against them in the circulation. It is influenced by the functionality of the Na,K-ATPase enzyme, which is localized in their membranes. The proposed review is focused on knowledge regarding changes in erythrocyte Na,K-ATPase activity, and their impact on erythrocyte deformability in various pathophysiological situations observed exclusively in human studies, as well as on the potential erytroprotective effects of selected natural nutritional antioxidants. A clear link between the erythrocyte properties and the parameters of oxidative stress was observed. The undesirable consequences of oxidative stress on erythrocyte quality and hemorheology could be at least partially prevented by intake of diverse antioxidants occurring naturally in foodstuffs. Despite intensive research concerning the effect of antioxidants, only a small number of investigations on erythrocyte properties in humans is available in databases. It is worth shifting attention from animal and in vitro experiments and focusing more on antioxidant administration in human studies in order to establish what type of antioxidant, in what concentration, and in which individuals it may provide a beneficial effect on the human organism, by protecting erythrocyte properties.

Prevention of tubulin/aldose reductase association delays the development of pathological complications in diabetic rats

In recent studies, we found that compounds derived from phenolic acids (CAFs) prevent the formation of the tubulin/aldose reductase complex and, consequently, may decrease the occurrence or delay the development of secondary pathologies associated with aldose reductase activation in diabetes mellitus. To verify this hypothesis, we determined the effect of CAFs on Na⁺,K⁺-ATPase tubulin-dependent activity in COS cells, ex vivo cataract formation in rat lenses and finally, to evaluate the antidiabetic effect of CAFs, diabetes mellitus was induced in Wistar rats, they were treated with different CAFs and four parameters were determinates: cataract formation, erythrocyte deformability, nephropathy and blood pressure. After confirming that CAFs are able to prevent the association between aldose reductase and tubulin, we found that treatment of diabetic rats with these compounds decreased membrane-associated acetylated tubulin, increased NKA activity, and thus reversed the development of four AR-activated complications of diabetes mellitus determined in this work. Based on these results, the existence of a new physiological mechanism is proposed, in which tubulin is a key regulator of aldose reductase activity. This mechanism can explain the incorrect functioning of aldose reductase and Na⁺,K⁺-ATPase, two key enzymes in the pathogenesis of diabetes mellitus. Moreover, we found that such alterations can be prevented by CAFs, which are able to dissociate tubulin/aldose reductase complex.

The Relationship between Erythrocytes and Diabetes Mellitus

High blood glucose level (hyperglycemia) is a leading indicator of diabetes mellitus (DM). Erythrocytes are the most abundant cells in the circulation and the first to perceive changes in plasma composition. Long-lasting hyperglycemia affects the structure and function of erythrocytes. The detection of erythrocyte-related indicators can provide a valuable reference for the prevention, diagnosis, and treatment of DM and its complications. This paper reviews the normal structure and function of erythrocytes, the changes in erythrocytes in patients with diabetes, and the role of erythrocytes in the development of diabetic complications to provide more indicators for the early prevention of DM complications and to monitor the therapeutic effect of DM.

Impaired deformability and association with density distribution of erythrocytes in patients with type 2 diabetes mellitus under treatment

BACKGROUND

Disturbed microcirculation is related to diabetic complications, and erythrocyte deformability is a critical factor regulating microcirculation.

OBJECTIVES

To know the relationship between the impaired deformability and density profile in diabetic erythrocytes.

METHODS

We recruited patients with type 2 diabetes (n = 15, diabetic group) and age- and sex-matched non-diabetic subjects (n = 15, control group). Erythrocyte density (ED) profile was obtained by the phthalate ester separation technique. ED distribution was fitted by sigmoidal curve, yielding specific gravity of phthalate ester allowing passage of half erythrocytes population (ED50) and slope factor. Erythrocyte deformability was estimated by our specific filtration technique.

RESULTS

Diabetic group showed significantly (p < 0.001) higher HbA1c and fasting blood glucose concentration. Erythrocyte deformability in diabetic group was impaired as compared with that in control group (p < 0.001) and proportional to HbA1c (p = 0.009). However, ED50 and the slope factor in diabetic group did not differ from respective parameters in control group.

CONCLUSIONS

This study demonstrated that erythrocyte deformability was impaired in diabetic patients even under treatment. HbA1c up to 7.5% is concluded not to alter the erythrocyte density but to impair the deformability, which might be a warning to clinicians for prevention of diabetic complications.

Potential Diagnostic Hemorheological Indexes for Chronic Kidney Disease in Patients With Type 2 Diabetes

Many studies have demonstrated that an alteration in hemorheological properties is closely correlated with diabetic microcirculatory diseases. However, most of these studies have been limited to animal studies or used a small number of clinical samples, due to a lack of effective point-of-care (POC) devices to measure such properties within clinical environments. Owing to recent developments in microfluidic technology, several hemorheological POC devices have been designed that allow for the possibility of conducting extensive clinical studies using hemorheological measurements. Here, we reviewed recent clinical studies of diabetic kidney disease (DKD) associated with hemorheological parameters. We found that RBC deformability alone did not show a significant difference according to the degree of DKD, whereas critical shear stress (CSS) was found to be closely related to the ratio of albumin to creatinine and glomerular filtration rate. We also reviewed studies that alteration of hemorheological properties are associated with the development of DKD, which showed that CSS could be considered as a potential index to diagnose other diabetic complications as well as DKD.