Determinants of erythrocyte ageing: a reappraisal

Dynamics of Individual Red Blood Cells Under Shear Flow: A Way to Discriminate Deformability Alterations

In this work, we compared the dynamics of motion in a linear shear flow of individual red blood cells (RBCs) from healthy and pathological donors (Sickle Cell Disease (SCD) or Sickle Cell-β-thalassemia) and of low and high densities, in a suspending medium of higher viscosity. In these conditions, at lower shear rates, biconcave discocyte-shaped RBCs present an unsteady flip-flopping motion, where the cell axis of symmetry rotates in the shear plane, rocking to and fro between an orbital angle ±ϕ observed when the cell is on its edge. We show that the evolution of ϕ depends solely on RBC density for healthy RBCs, with denser RBCs displaying lower ϕ values than the lighter ones. Typically, at a shear stress of 0.08 Pa, ϕ has values of 82 and 72° for RBCs with average densities of 1.097 and 1.115, respectively. Surprisingly, we show that SCD RBCs display the same ϕ-evolution as healthy RBCs of same density, showing that the flip-flopping behavior is unaffected by the SCD pathology. When the shear stress is increased further (above 0.1 Pa), healthy RBCs start going through a transition to a fluid-like motion, called tank-treading, where the RBC has a quasi-constant orientation relatively to the flow and the membrane rotates around the center of mass of the cell. This transition occurs at higher shear stresses (above 0.2 Pa) for denser cells. This shift toward higher stresses is even more remarkable in the case of SCD RBCs, showing that the transition to the tank-treading regime is highly dependent on the SCD pathology. Indeed, at a shear stress of 0.2 Pa, for RBCs with a density of 1.097, 100% of healthy RBCs have transited to the tank-treading regime vs. less than 50% SCD RBCs. We correlate the observed differences in dynamics to the alterations of RBC mechanical properties with regard to density and SCD pathology reported in the literature. Our results suggest that it might be possible to develop simple non-invasive assays for diagnosis purpose based on the RBC motion in shear flow and relying on this millifluidic approach.

Migration velocity of red blood cells in microchannels

The lateral migration of red blood cells (RBCs) in confined channel flows is an important ingredient of microcirculatory hydrodynamics and is involved in the development of a cell free layer near vessel walls and influences the distribution of RBCs in networks. It is also relevant to a number of lab-on-chip applications. This migration is a consequence of their deformability and is due to the combined effects of hydrodynamic wall repulsion and the curvature of the fluid velocity profile. We performed microfluidic experiments with dilute suspensions of RBCs in which the trajectories and migration away from the channel wall are analyzed to extract the mean behavior, from which we propose a generic scaling law for the transverse migration velocity valid in a whole range of parameters relevant to microcirculatory and practical situations. Experiments with RBCs of different mechanical properties (separated by density gradient sedimentation or fixed with glutaraldehyde) show the influence of this parameter which can induce significant dispersion of the trajectories.

The Clinical Application of Ozonetherapy

The reader may be eager to examine in which diseases ozonetherapy can be proficiently used and she/he will be amazed by the versatility of this complementary approach (Table 9 1). The fact that the medical applications are numerous exposes the ozonetherapist to medical derision because superficial observers or sarcastic sceptics consider ozonetherapy as the modern panacea. This seems so because ozone, like oxygen, is a molecule able to act simultaneously on several blood components with different functions but, as we shall discuss, ozonetherapy is not a panacea. The ozone messengers ROS and LOPs can act either locally or systemically in practically all cells of an organism. In contrast to the dogma that “ozone is always toxic”, three decades of clinical experience, although mostly acquired in private clinics in millions of patients, have shown that ozone can act as a disinfectant, an oxygen donor, an immunomodulator, a paradoxical inducer of antioxidant enzymes, a metabolic enhancer, an inducer of endothelial nitric oxide synthase and possibly an activator of stem cells with consequent neovascularization and tissue reconstruction.

The James Blundell Award Lecture 2007: do we really understand immune red cell destruction?

We have learned a great deal about immune red blood cell (RBC) destruction since the elaboration of biochemical/immunological interactions of antibodies, complement and macrophages during the past 50 years. We first learned about the direct lysis of RBCs involving complement. We then learned of the role of the macrophage (particularly in the spleen and the liver) in initiating phagocytosis and antibody-dependent cytotoxicity of antibody-coated RBCs. Later, as the complexities of the human complement system were unravelled, we learned that complement-coated RBCs that were not directly haemolysed could interact with macrophages and that specific complement molecules on the RBC membrane could lead to a phagocytic event or the RBC (although heavily coated with complement) could survive normally. The application of isotope-labelling procedures (e.g. (51)Cr) for RBC survival (starting in the 1950s) advanced our knowledge considerably. Advances in knowledge in immunology helped us understand the complexity of the immunoglobulins (e.g. subclasses) and the specific receptors on macrophages and their role in immune haemolysis. Nevertheless, after more than 30 years researching this area, I am sometimes embarrassed to realize how much I cannot explain. Why do some patients have severe haemolytic transfusion reactions because of antibodies that are only detectable by one technique or not detectable by any? How do we explain autoimmune haemolytic anaemia with negative direct antiglobulin tests (DATs)? Why do RBCs strongly coated with immunoglobulin (Ig)G1 or IgG3 sometimes have normal survival? Are cells, other than macrophages, involved in immune RBC destruction? Could the relative amount of cytotoxicity vs. phagocytosis explain different clinical findings and response to treatment? How do we explain 'hyperhaemolysis' in sickle cell disease? Could novel mechanisms involving IgG glycosylation, CD47, 'armed' macrophages, bystander lysis, antibody activated reactive oxygen species, natural killer cells or antibody perturbation of RBC membrane be involved? Why do RBCs die after circulating for 100-120 days in healthy individuals? How should we define a 'clinically significant' antibody; how do we evaluate this? So many questions, so little time!

Alterations of erythrocyte structure and cellular susceptibility in patients with chronic renal failure: effect of haemodialysis and oxidative stress

The aim of this study was to investigate erythrocytes rheological behaviour, membrane dynamics and erythrocytes susceptibility to disintegration upon strong oxidative stress induced by dialysis or by external H(2)O(2) among patients with CRF. EPR spectrometry was used to investigate alterations in physical state of cellular components. Generated ROS production induced: (1) significant increase of membrane fluidity in CRF erythrocytes treated with H(2)O(2) (p<0.005) and at 60 min of haemodialysis (p<0.05), (2) significant decrease of cytoskeletal protein-protein interactions (p<0.005) and (3) cellular osmotic fragility (p<0.0005). H(2)O(2) exacerbated these changes. Erythrocytes from CRF patients have changed rheological behaviour and present higher susceptibility to disintegration. Erythrocytes membrane characteristics indicate that CRF patients possess younger and more flexible cells, which are more susceptible to oxidative stress. This may contribute to the shortened survival of young erythrocytes in CRF patients.

A physicochemical investigation on the effects of ozone on blood

Ozonation of either human whole blood or saline-washed erythrocytes causes considerable damage to the latter and this result has opened a controversy. With the benefit of hindsight, it appears logical that once erythrocytes are deprived of the potent antioxidants of plasma, they become very sensitive to the oxidant effects of ozone. The aim of the present work was to perform a physical-chemical evaluation of some critical parameters able to clarify this issue. We have ascertained that when whole blood is exposed to the appropriate ozone doses used in human therapy, no damage ensues while saline-washed erythrocytes undergo conspicuous haemolysis. The dogma that ozone is always toxic is incorrect because its reactivity below the concentration of 80mug/mL can be controlled by the plasmatic antioxidant system.

Generation of mice deficient for macrophage galactose- and N-acetylgalactosamine-specific lectin: limited role in lymphoid and erythroid homeostasis and evidence for multiple lectins

Macrophage receptors function in pattern recognition for the induction of innate immunity, in cellular communication to mediate the regulation of adaptive immune responses, and in the clearance of some glycosylated cells or glycoproteins from the circulation. They also function in homeostasis by initiating the engulfment of apoptotic cells. Evidence has suggested that macrophage receptors function to recognize cells that are destined for programmed cell death but not yet overtly apoptotic. We have examined the function of a macrophage receptor specific for unsialylated glycoproteins, known as the mouse macrophage galactose- and N-acetylgalactosamine-specific lectin (mMGL) (Ii et al., J. Biol. Chem. 265:11295-11298, 1990; Sato et al., J. Biochem. [Tokyo] 111:331-336, 1992; Yamamoto et al., Biochemistry 33:8159-8166, 1994). With targeted disruption, we tested whether mMGL is necessary for macrophage function, controlled thymic development, the loss of activated CD8 T cells, and the turnover of red blood cells. Evidence indicates that mMGL may play a nonessential role in several of these macrophage functions. Experiments are presented that indicate the existence of another galactose- and N-acetylgalactosamine-recognizing lectin distinct from mMGL. This may explain the absence of a strong phenotype in mMGL-deficient mice.

In vitro erythrocidal activity of activated spleen cells from young and old mice

We have recently reported that activated mouse spleen mononuclear cells (MNCs) efficiently lyse autologous erythrocytes in vitro (Saxena and Chandrasekhar, 2000). In the present study, we have investigated erythrocyte-depleting ability (EDA) of spleen MNCs from young and old mice. Time kinetics of survival of erythrocytes in mitogen-activated spleen cell cultures indicated that the erythrocyte depletion was significantly faster in young spleen cell cultures than in the old. Poorer EDA of old MNCs was in spite of the fact that the susceptibility to lysis actually increased in erythrocytes from old mice. Erythrocytes opsonized by a hamster anti mouse Fas monoclonal antibody, were destroyed with a much greater efficiency by young MNCs, whereas the corresponding effect of opsonization was only moderate for old MNCs. Depletion of macrophages from MNC preparations by plastic adherence as well as carbonyl-iron and magnet treatment had a marginal if any effect on EDA of young and old mouse MNCs, indicating that a lower lymphocyte-associated erythrocidal activity as one of the factors responsible for overall lower EDA associated with spleen derived MNCs of old mice.

Acetylcholinesterase activity in chronic renal failure

Twenty healthy subjects and 39 Chronic Renal Failure patients (CRF-patients) maintained on chronic hemodialysis were used in this investigation to study the changes in acetylcholinesterase (AChE) activity of red blood cells (RBCs). The CRF-patients were all undergoing hemodialysis treatment. AChE activity from the CRF-patients was determined before and after dialysis. An additional objective was to study the effect of chronic renal failure on human red blood cell aging. Blood samples were drawn from controls and CRF-patients in tubes containing EDTA or sodium heparin as an anticoagulant. Red blood cells were purified to avoid interference with monocytes, reticulocytes and leukocytes. The purified RBCs were subfractionated into young (y) (1.08-1.09), mid (m) (1.09-1.11) and old (o) (1.11-1.12) percoll density (g/mL) fractions using a discontinous percoll gradient. The mean +/- SD AChE per gram hemoglobin (U/g Hgb) activities in whole blood (WB), purified human red blood cells (PRBCs), young human red blood cells (y-RBCs), mid age human red blood cells (m-RBCs) and old human red blood cells (o-RBCs) in CRF-patients were 31.2+/-3.43, 29.3+/-3.26, 30.4+/-3.91, 25.1+/-5.25, 17.1+/-6.02 in females and 29.8+/-5.39, 28.8+/-5.29, 28.7+/-5.29, 23.7+/-5.39 and 16.0+/-5.60 in males. AChE activity from CRF-patients were higher than that found in the control subjects. The aging of human RBCs in both the controls and CRF-patients showed a progressive reduction in AChE activity. AChE activity of RBCs from female CRF-patients were significantly higher (p < 0.05) than that of the female control subjects. The RBCs isolated from male CRF-patients showed a higher AChE activity than control males, but a significant difference was only observed with the mid-age-cells. These studies further indicate that AChE activity remained insignificantly different in the various density based age subfractions of RBCs of both CRF-patients and controls.

Autohaemotherapy after treatment of blood with ozone. A reappraisal

Autohaemotherapy, involving bland treatment ex vivo of blood with ozone and prompt reinfusion into the donor, is a procedure mainly performed in central Europe, which is claimed to have therapeutic value in circulatory disorders, viral diseases and cancer. This practice is mostly performed in private clinics, and good clinical trials have not been published, which has understandably given rise to prejudice and scepticism. By analysing possible mechanisms of action and current hypotheses, this report attempts to explain how this procedure can be useful in such disparate diseases. The current state of the art is presented objectively, the lack of toxicity is documented, and the rationale and therapeutic advantages are discussed, with the aim of eliciting interest in carrying out controlled clinical trials.

Red blood cell age dependent modifications of inositol 1,4,5-trisphosphate

The level of inositol 1,4,5-trisphosphate (Ins1,4,5P3) was determined in human and rabbit red blood cells of different ages. In human erythrocytes, fractionated by discontinuous density gradient centrifugation, Ins1,4,5P3 was 290 nM in the 0.3% low density (youngest) cells compared to values of 107 nM in the whole red blood cell population. A progressive increase in Ins1,4,5P3 was then observed during erythrocyte aging from values of 63 nM in mature erythrocytes to 128 nM in the oldest cells. Determinations of Ins1,4,5P3 in rabbit erythrocytes provided values of 180 nM. Phenylhydrazine was administered to three animals to induce reticulocytosis. Ins1,4,5P3 in rabbit reticulocytes was significantly lower than in the whole red cell population, remained lower in young red blood cells and then increased to normal values during cell maturation. These results provide evidence for an increase of Ins1,4,5P3 during red blood cell aging and could contribute to explain the age-dependent loss of deformability and of Ca2+ homeostasis of these cells.

Erythrocyte rheology

Two main subjects of erythrocyte rheology, deformation and aggregation, are discussed in detail, on the basis of biochemical structure. The close relationship between the life span (or cell aging) and the rheology of individual erythrocytes is also briefly described. A currently important problem is emphasized, that is, the molecular aspect of the dynamic cytoskeletal structure and the mechanism of its regulation. This concerns not only the rheological function and the survival of circulating erythrocytes, but also the pathophysiology of abnormal erythrocytes.

Osmotic fragility model for red cell populations

A model that predicts the osmotic fragility curve of a red cell population is developed by relating the critical osmotic pressure to the size distribution of the cells, determined by resistive pulse spectroscopy. Two of the parameters involved, namely the normalized osmotic volume correction, B, and the swelling index, k, are previously determined from the experimental average properties of the population. From these values the critical volume of the cell is obtained, and is shown to be 6-12% larger than the first spherical volume, obtained from an independent experiment. A new parameter, n, a measure of the surface area distribution of the cells, is incorporated through a simple function that relates the critical volume to the size of the cells, and is theoretically shown to be linked to parameters k and B. The model is used to fit and interpret fragility data obtained in this laboratory for normal and sickle cell samples. From the values of n obtained for normal samples, the model predicts an essentially constant surface-to-volume ratio within an individual's cell population. For sickle cell samples, instead, the value of index n is negative, thereby supporting an increase in excess surface area as cell size decreases. Both findings are in agreement with direct observations reported in the literature. It is concluded that this set of parameters may be used to develop an index classification of blood disorders.

Red blood cell phagocytosis and lysis following oxidative damage by phenylhydrazine

Red blood cells exposed in vitro to phenylhydrazine acquired Heinz bodies, bound autologous IgG and were then phagocytized when incubated with autologus mononuclear phagocytes. In vivo, phenylhdyrazine administered to rabbits, caused the appearance of high plasma hemoglobin levels and hemoglobinuria as well as Heinz body formations and IgG binding to erythrocytes. This suggests that while in vitro the main mechanism of red cell removal seems to be phagocytoses, in vivo both intravascular hemolysis and phagocytosis are active processes. Preliminary biochemical studies on phenylhydrazine-exposed erythrocytes showed that together with the well-known appearance of Heinz bodies, methemoglobin and a drop in reduced glutathione, this drug also causes ATP depletion. This is initially concomitant with the appearance of ADP and AMP and subsequently hypoxantine. Thus, irreversible ATP depletion may contribute to the genesis of the hemolytic process observed in vivo.

Effects of shape and size on red blood cell deformability: a static bending analysis

When flowing down a tapered tube, such as a narrow capillary, red blood cells (RBCs) are subject to deformation, the first event of which is folding in a pancake manner. The RBC deformability is reduced during cell ageing, a phenomenon that may reflect alterations in intracellular viscosity, membrane rigidity or RBC shape. Age related shape changes and their importance for increased RBC rigidity were theoretically analysed. The average empirically observed RBC profile is shown to offer little resistance to bending as compared to other, theoretically possible profiles of the same membrane area and RBC volume. Because of a decrease in projected area (diameter size), and therefore in pressure load, the pressure needed to initiate folding of an old RBC is between 20 and 55% higher than that required to fold a young one if, during RBC ageing, membrane area to cell volume ratio is constant as empirically observed. This difference exists whether the RBC is mathematically treated as a solid body or as a membrane shell.

Preferential phagocytosis of in vivo aged murine red blood cells by a macrophage-like cell line

The ability of an established line of mouse macrophages (IC-21) to ingest red blood cells (RBC) aged in vivo was assessed. RBC populations of increasing age were prepared in mice by serial hypertransfusion, a procedure that inhibits erythropoiesis. Mouse RBC with a mean age of about 58 d (normal RBC life span, 60 d) had a circulating half-life of less than 1 d when transfused into normal mice. IC-21 macrophages ingested the in vivo aged RBC in preference to RBC from normal mice (mean RBC age, 30 d). RBC isolated from mice 10 d after being released from one red blood cell lifespan (60 d) of inhibited erythropoiesis (mean RBC age 5 d) were ingested significantly less than RBC from normal mice. The IC-21 macrophage line used with in vivo aged RBC affords a highly defined model system for identifying the mechanism(s) of macrophage-mediated homeostasis.

Interaction between erythroblasts and macrophages in vitro: effect of neuraminidase-treatment of erythroblasts and the role of serum factors

Some factors influencing the interaction in vitro between dimethylsulphoxide-induced Friend leukaemia erythroblasts (IFLE) and syngeneic mouse peritoneal macrophages (M phi) have been investigated. Desialation of erythroblasts by treatment with neuraminidase resulted in a significant increase in their association with and ingestion by M phi. In addition, the interaction with M phi of both neuraminidase-treated and untreated IFLE was found to be influenced by a heat-stable serum factor. gamma-globulin markedly enhanced the weak IFLE-M phi interaction which occurred at low serum concentration suggesting that the heat-stable factor may be an immunoglobulin. Desialation of the IFLE-rendered them agglutinable by peanut lectin which was used as a probe for neuraminidase-induced membrane changes. By contrast, cycloheximide treatment of IFLE which also enhances their interaction with M phi, did not result in the exposure of receptors for this lectin. It is proposed that both desialation and cycloheximide treatment of IFLE lead to secondary alterations in their membrane structure which renders them recognizable by M phi.

The age-dependent metabolic decline of the red blood cell

The oxidative and non-oxidative utilization of glucose was evaluated in human erythrocytes of different ages, separated by density gradient ultracentrifugation. Young red blood cells are able to metabolize 2.5 times more glucose than old ones; on the other hand, the amount of glucose utilized via the hexose monophosphate shunt does not show any age dependence. Glucose metabolism evaluated during in vivo ageing of a rabbit red cell population shows results very similar to those obtained for human cells. Metabolic stimulation of glucose utilization by high phosphate in both young and old human red cells increases glucose utilization by 40%. In the same way young and old erythrocytes were able to increase the amount of glucose metabolized via the hexose monophosphate shunt when an oxidative stimulus (methylene blue) was introduced. Human erythrocytes of different age possess similar abilities to transport glucose so that an age-dependent defect in glucose transport can be excluded. The ATP content of human and rabbit red blood cells, as a function of cell age, follows the decrease in glucose metabolized via the Embden-Meyerhof pathway. Reduced glutathione, on the other hand, after a small decrease associated with the "maturation" of reticulocytes into red cells, remains constant like the rate of the hexose monophosphate shunt.

The relationship between the osmotic fragility of human erythrocytes and cell age

Erythrocytes in a normal blood sample are hemolyzed over a range of hypotonic salt concentrations. In order to investigate the relationship between the distribution of osmotic fragilities and the distribution of cellular ages, the osmotic fragility has been compared with three indices of cellular age. The activity of glutamic-oxalacetic transaminase (GOT) and the percentage hemoglobin A1C were measured in samples hemolyzed in different hypotonic salt concentrations. The osmotic fragility curve was also obtained for cells of different density separated by centrifugation. These experiments indicate that the fragility distribution is not an accurate reflection of the distribution of cellular ages. The mean fragility for older cells is higher than that of younger cells. However, cellular aging does not produce a gradual increase in osmotic fragility. Instead, it seems to produce changes which can both increase and decrease the fragility, resulting in a broader distribution of fragilities with some of the older cells actually less fragile than the younger ones.