Changes in Blood Cell Deformability in Chorea-Acanthocytosis and Effects of Treatment With Dasatinib or Lithium

Misshaped red blood cells (RBCs), characterized by thorn-like protrusions known as acanthocytes, are a key diagnostic feature in Chorea-Acanthocytosis (ChAc), a rare neurodegenerative disorder. The altered RBC morphology likely influences their biomechanical properties which are crucial for the cells to pass the microvasculature. Here, we investigated blood cell deformability of five ChAc patients compared to healthy controls during up to 1-year individual off-label treatment with the tyrosine kinase inhibitor dasatinib or several weeks with lithium. Measurements with two microfluidic techniques allowed us to assess RBC deformability under different shear stresses. Furthermore, we characterized leukocyte stiffness at high shear stresses. The results showed that blood cell deformability–including both RBCs and leukocytes - in general was altered in ChAc patients compared to healthy donors. Therefore, this study shows for the first time an impairment of leukocyte properties in ChAc. During treatment with dasatinib or lithium, we observed alterations in RBC deformability and a stiffness increase for leukocytes. The hematological phenotype of ChAc patients hinted at a reorganization of the cytoskeleton in blood cells which partly explains the altered mechanical properties observed here. These findings highlight the need for a systematic assessment of the contribution of impaired blood cell mechanics to the clinical manifestation of ChAc.

The Relationship Between Aggregation and Deformability of Red Blood Cells in Health and Disease

The molecular organization of the membrane of the red blood cell controls cell morphology and function and is thereby a main determinant of red blood cell homeostasis in the circulation. The role of membrane organization is prominently reflected in red blood cell deformation and aggregation. However, there is little knowledge on whether they are controlled by the same membrane property and if so, to what extent. To address the potential interdependence of these two parameters, we measured deformation and aggregation in a variety of physiological as well as pathological conditions. As a first step, we correlated a number of deformability and aggregation parameters in red blood cells from healthy donors, which we obtained in the course of our studies on red blood cell homeostasis in health and disease. This analysis yielded some statistically significant correlations. Also, we found that most of these correlations were absent in misshapen red blood cells that have an inborn defect in the interaction between the membrane and the cytoskeleton. The observations suggest that deformability and aggregation share at least one common, membrane-related molecular mechanism. Together with data obtained after treatment with various agents known to affect membrane organization in vitro, our findings suggest that a phosphorylation-controlled interaction between the cytoskeleton and the integral membrane protein band 3 is part of the membrane-centered mechanism that plays a role in deformability as well as aggregation.

The impact of circulation in a heart-lung machine on function and survival characteristics of red blood cells

Extracorporeal circulation is accompanied by changes in red blood cell morphology and structural integrity that affect cell function and survival, and thereby may contribute to the various side effects of heart–lung machine‐assisted surgery. Our main objectives were to determine the effect of circulation of red blood cells in a stand‐alone extracorporeal circuit on several parameters that are known to be affected by, as well as contribute to red blood cell aging. As a source of RBCs, we employed blood bank storage units of different ages. In order to assess the relevance of our in vitro observations for the characterization of extracorporal circulation technology, we compared these changes in those of patients undergoing extracorporeal circulation‐assisted cardiac surgery. Our results show that circulation in a heart–lung machine is accompanied by changes in red blood cell volume, an increase in osmotic fragility, changes in deformability and aggregation behavior, and alterations in the exposure of phosphatidylserine and in microvesicle generation. RBCs from 1‐week‐old concentrates showed the highest similarities with the in vivo situation. These changes in key characteristics of the red blood cell aging process likely increase the susceptibility of red blood cells to the various mechanical, osmotic, and immunological stress conditions encountered during and after surgery in the patient’s circulation, and thereby contribute to the side effects of surgery. Thus, aging‐related parameters in red blood cell structure and function provide a foundation for the validation and improvement of extracorporeal circulation technology.

Vesiculation of Red Blood Cells in the Blood Bank: A Multi-Omics Approach towards Identification of Causes and Consequences

Microvesicle generation is an integral part of the aging process of red blood cells in vivo and in vitro. Extensive vesiculation impairs function and survival of red blood cells after transfusion, and microvesicles contribute to transfusion reactions. The triggers and mechanisms of microvesicle generation are largely unknown. In this study, we combined morphological, immunochemical, proteomic, lipidomic, and metabolomic analyses to obtain an integrated understanding of the mechanisms underlying microvesicle generation during the storage of red blood cell concentrates. Our data indicate that changes in membrane organization, triggered by altered protein conformation, constitute the main mechanism of vesiculation, and precede changes in lipid organization. The resulting selective accumulation of membrane components in microvesicles is accompanied by the recruitment of plasma proteins involved in inflammation and coagulation. Our data may serve as a basis for further dissection of the fundamental mechanisms of red blood cell aging and vesiculation, for identifying the cause-effect relationship between blood bank storage and transfusion complications, and for assessing the role of microvesicles in pathologies affecting red blood cells.

Red Blood Cell Homeostasis and Altered Vesicle Formation in Patients With Paroxysmal Nocturnal Hemoglobinuria

A subset of the red blood cells (RBCs) of patients with paroxysmal nocturnal hemoglobinuria (PNH) lacks GPI-anchored proteins. Some of these proteins, such as CD59, inhibit complement activation and protect against complement-mediated lysis. This pathology thus provides the possibility to explore the involvement of complement in red blood cell homeostasis and the role of GPI-anchored proteins in the generation of microvesicles (MVs) in vivo. Detailed analysis of morphology, volume, and density of red blood cells with various CD59 expression levels from patients with PNH did not provide indications for a major aberration of the red blood cell aging process in patients with PNH. However, our data indicate that the absence of GPI-anchored membrane proteins affects the composition of red blood cell-derived microvesicles, as well as the composition and concentration of platelet-derived vesicles. These data open the way toward a better understanding on the pathophysiological mechanism of PNH and thereby to the development of new treatment strategies.

Nanomechanics of Extracellular Vesicles Reveals Vesiculation Pathways

Extracellular vesicles (EVs) are emerging as important mediators of cell-cell communication as well as potential disease biomarkers and drug delivery vehicles. However, the mechanical properties of these vesicles are largely unknown, and processes leading to microvesicle-shedding from the plasma membrane are not well understood. Here an in depth atomic force microscopy force spectroscopy study of the mechanical properties of natural EVs is presented. It is found that several natural vesicles of different origin have a different composition of lipids and proteins, but similar mechanical properties. However, vesicles generated by red blood cells (RBC) at different temperatures/incubation times are different mechanically. Quantifying the lipid content of EVs reveals that their stiffness decreases with the increase in their protein/lipid ratio. Further, by maintaining RBC at "extreme" nonphysiological conditions, the cells are pushed to utilize different vesicle generation pathways. It is found that RBCs can generate protein-rich soft vesicles, possibly driven by protein aggregation, and low membrane-protein content stiff vesicles, likely driven by cytoskeleton-induced buckling. Since similar cortical cytoskeleton to that of the RBC exists on the membranes of most mammalian cells, our findings help advancing the understanding of the fundamental process of vesicle generation.

Alterations of red blood cell metabolome in overhydrated hereditary stomatocytosis

Overhydrated hereditary stomatocytosis, clinically characterized by hemolytic anemia, is a rare disorder of the erythrocyte membrane permeability to monovalent cations, associated with mutations in the Rh-associated glycoprotein gene. We assessed the red blood cell metabolome of 4 patients with this disorder and showed recurrent metabolic abnormalities associated with this disease but not due to the diminished half-life of their erythrocytes. Glycolysis is exhausted with accumulation of ADP, pyruvate, lactate, and malate. Ascorbate metabolic pathway is altered probably due to a limited entry of dehydroascorbate. Although no major oxydative stress has been reported in patients with overhydrated hereditary stomatocytosis, we found decreased amounts of oxydized glutathione, creatine and ergothioneine, suggesting transporter abnormalities and/or uncharacterized oxydative stress. These results pinpoint major metabolic defects of overhydrated hereditary stomatocytosis erythrocytes and emphasize the relevance of red blood cell metabolomics for a better understanding of the pathophysiological bases of hemolytic anemia associated with erythrocyte abnormalities.

Recurrent and founder mutations in the Netherlands: Extensive clinical variability in Marfan syndrome patients with a single novel recurrent fibrillin-1 missense mutation

Background/Methods. Marfan syndrome (MFS) is a heritable connective tissue disorder usually caused by a mutation in the fibrillin 1 (FBN1) gene. Typical characteristics of MFS that have been described include dolichostenomelia, ectopia lentis and aortic root dilatation. However, there is great clinical variability in the expression of the syndrome's manifestations, both between and within families. Here we discuss the clinical variability of MFS by describing a large fourgeneration Dutch family with MFS.Results. Nineteen individuals of one family with a single missense FBN1 mutation (c.7916A>G) were identified. The same mutation was found in one unrelated person. Clinical variability was extensive and not all mutation carriers fulfilled the diagnostic criteria for MFS. Some patients only expressed mild skeletal abnormalities, whereas aortic root dilation was present in eight patients, an acute type A aortic dissection was recorded in two other patients, and a mitral valve prolapse was present in eight patients. In some patients cardiac features were not present on initial screening, but did however develop over time.Conclusion. MFS is a clinically highly variable syndrome, which means a meticulous evaluation of suspected cases is crucial. Mutation carriers should be re-evaluated regularly as cardiovascular symptoms may develop over time. (Neth Heart J 2010;18:85-9.).

Collaboration on progress testing in medical schools in the Netherlands

Progress testing in the Netherlands was originally developed at Maastricht University. Since the late 1990s, a collaboration has started between three medical schools to jointly produce and administer the progress test. Currently, the progress test is administered to five out of eight medical schools in the Netherlands. The collaboration has led to substantial decrease in necessary resources per participating school. Also, the data provide a rich source for comparisons between schools and can be instrumental in inducing improvements to the curricula. Logistics of large-scale administrations and possible differences of views on item quality could be seen as a disadvantage. Also, it is not always easy to fit the test in the local regulatory structure, because it is only partly owned by each individual school. Important lessons for us have been that the advantages of the collaboration clearly outweigh the disadvantages. Of course, good collegial communication is needed, but this is not enough: a legal binding agreement has to be drawn up. Most importantly, such a collaboration creates a critical mass to enable multi-centre research and development projects on progress testing.

A modified Raz bladder neck suspension operation. Results of a one to three years follow-up investigation

OBJECTIVE

Long term follow-up study of stress incontinence operations shows a declining success rate in time, especially for the needle suspension technique. We evaluated the long term results of a modified bladder neck suspension operation.

METHODS

From 01-12-87 till 01-12-89 a total of 42 modified Raz bladder neck suspensions for stress incontinence were performed. Early evaluation at three months had shown a cure rate of 93%. Long term (mean 27 months) results were evaluated using a questionnaire.

RESULTS

Follow-up of 41 patients showed that ten patients (24%) were cured. Fourteen (34%) considered their situation improved and acceptable, despite mild incontinence. Seventeen patients (40%) considered their situation still unacceptable, half of them (nine patients, 21%) had another operation for incontinence done within two years.

CONCLUSIONS

We conclude that this one to three years follow-up shows that the modified Raz bladder neck suspension, in our hands, has, in spite of a good short term result, a relatively low long term success rate.

Membrane channel protein abnormalities and autoantibodies in neurological disease

Immunological analogues of band 3, the anion transporter of the human erythrocyte, have been identified in all cells, including both isolated neurons and neurons of the central nervous system. We hypothesized that the anion channel is altered in neurological disease associated with choreiform movements because gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in mammalian brain, binds to its receptor and opens an integral membrane chloride channel. In order to examine this hypothesis, we studied a family with a serious, progressive, genetic neurologic disorder with acanthocytosis (choreoacanthocytosis) that resembles Huntington's chorea. We selected choreoacanthocytosis because erythrocytes, which are readily obtained, are affected in this disease as well as the central nervous system. Biochemical studies of erythrocytes from the proposita, mother, and brother revealed that sulfate transport Vmax was increased, and glucose efflux was decreased. Erythrocytes exhibited immunological changes indicative of cellular aging/transporter damage. In addition, transporter reactive antibodies were present. This is the first evidence for abnormalities of membrane transport in this neurologic disorder.

Alteration in membrane protein band 3 associated with accelerated erythrocyte aging

We report a human band 3 alteration that is associated with anemia as determined by a reticulocyte count of 20%. Erythrocyte defects included increased IgG binding, increased breakdown products of band 3, and altered anion- and glucose-transport activity in middle-aged cells. These changes were observed during normal erythrocyte aging in situ. Binding of ankyrin to band 3 was normal. Serum/cell crossover studies indicated that a neoantigen appears on the propositus' erythrocytes to which IgG from both propositus and control serum binds as measured with a protein A binding assay. IgG eluted from the propositus' erythrocytes appeared to have a specificity for senescent cell antigen as determined by a phagocytosis inhibition assay. Immunoelectron microscopy showed that antibodies to band 3, which do not normally bind to intact erythrocytes, bound to the propositus' erythrocytes. Antibody 980 binds to normal old cells but not young or middle-aged cells. It also binds to a distinct region of band 3 in immunoblots of membranes from the propositus' middle-aged cells. Cells from both of the propositus' parents exhibited increased IgG binding and altered anion and glucose transport. The results of these studies suggest that (i) band 3 is aging prematurely in erythrocytes from the propositus, (ii) senescent cell antigen appears on the propositus' middle-aged red cells, and (iii) band 3 alterations observed in the propositus may have a genetic component.

Vitamin B12 and bile acid metabolism in patients with partial iieal resection

The vitamin B12 and bile acid metabolism was studied in 20 patients in whom a standardized Bricker procedure without irradiation was performed. No significant vitamin B12 malabsorption, steatorrhea, fecal bile acid loss or bile acid deconjugation was found. Therefore, no long-term adverse metabolic consequences of segmental preterminal ileal resection are to be expected in these patients.

Enzyme histochemical investigation of an adenomatoid tumor

Enzyme histochemical study of an adenomatoid tumor of the epididymis revealed an enzyme pattern identical to that of the rete testis. Histogenesis from the same primordium may be suggested.