Membrane Lesions and Reduced Life Span of Red Blood Cells in Preeclampsia as Evidenced by Atomic Force Microscopy

Preeclampsia (PE) presents with maternal de novo hypertension and significant proteinuria and is one of the leading causes of maternal and perinatal morbidity and mortality with unknown etiology. The disease is associated with inflammatory vascular response and severe red blood cell (RBC) morphology changes. This study examined the nanoscopic morphological changes of RBCs from PE women versus normotensive healthy pregnant controls (PCs) and non-pregnant controls (NPCs) applying atomic force microscopy (AFM) imaging. The results revealed that the membrane of fresh PE RBCs differed significantly from healthy ones by the presence of invaginations and protrusions and an increased roughness value (R_rms) (4.7 ± 0.8 nm for PE vs. 3.8 ± 0.5 nm and 2.9 ± 0.4 nm for PCs and NPCs, respectively). PE-cells aging resulted in more pronounced protrusions and concavities, with exponentially increasing R_rms values, in contrast to the controls, where the R_rms parameter decreased linearly with time. The R_rms, evaluated on a 2 × 2 µm² scanned area, for senescent PE cells (13 ± 2.0 nm) was significantly higher (p < 0.01) than that of PCs (1.5 ± 0.2 nm) and NPCs (1.9 ± 0.2 nm). Furthermore, the RBCs from PE patients appeared fragile, and often only ghosts were observed instead of intact cells at 20-30 days of aging. Oxidative-stress simulation on healthy cells led to RBC membrane features similar to those observed for PE cells. The results demonstrate that the most pronounced effects on RBCs in PE patients are related to impaired membrane homogeneity and strongly altered roughness values, as well as to vesiculation and ghost formation in the course of cell aging.

Surprising Structural and Functional Properties of Favism Erythrocytes Are Linked to Special Metabolic Regulation: A Cell Aging Study

Favism uniquely arises from a genetic defect of the Glucose-6 Phosphate Dehydrogenase (G6PD) enzyme and results in a severe reduction of erythrocytes' (RBCs) reducing power that impairs the cells' ability to respond to oxidative stresses. After exposure to fava beans or a few other drugs, the patients experience acute hemolytic anemia due to RBCs' lysis both intra and extra-vascularly. In the present paper, we compared selected biochemical, biophysical, and ultra-morphological properties of normal RBCs and cells from favism patients measured along cellular aging. Along the aging path, the cells' characteristics change, and their structural and functional properties degrade for both samples, but with different patterns and effectors that have been characterized in biophysical and biochemical terms. In particular, the analysis revealed distinct metabolic regulation in G6DP-deficient cells that determines important peculiarities in the cell properties during aging. Remarkably, the initial higher fragility and occurrence of structural/morphological alterations of favism cells develop, with longer aging times, into a stronger resistance to external stresses and higher general resilience. This surprisingly higher endurance against cell aging has been related to a special mechanism of metabolic regulation that permits lower energy consumption in environmental stress conditions. Our results provided a direct and coherent link between the RBCs' metabolic regulation and the cell properties that would not have been possible to establish without an investigation performed during aging. The consequences of this new knowledge, in particular, can be discussed in a more general context, such as understanding the role of the present findings in determining the characteristics of the favism pathology as a whole.

Mechano-Transduction Boosts the Aging Effects in Human Erythrocytes Submitted to Mechanical Stimulation

Erythrocytes' aging and mechano-transduction are fundamental cellular pathways that determine the red blood cells' (RBCs) behavior and function. The aging pattern can be influenced, in morphological, biochemical, and metabolic terms by the environmental conditions. In this paper, we studied the effect of a moderate mechanical stimulation applied through external shaking during the RBCs aging and revealed a strong acceleration of the aging pattern induced by such stimulation. Moreover, we evaluated the behavior of the main cellular effectors and resources in the presence of drugs (diamide) or of specific inhibitors of the mechano-transduction (probenecid, carbenoxolone, and glibenclamide). This approach provided the first evidence of a direct cross-correlation between aging and mechano-transduction and permitted an evaluation of the overall metabolic regulation and of the insurgence of specific morphological features, such as micro-vesicles and roughness alterations. Overall, for the first time the present data provided a schematic to understand the integration of distinct complex patterns in a comprehensive view of the cell and of its interactions with the environment. Mechano-transduction produces structural effects that are correlated with the stimulation and the strength of the environmental stimulation is paramount to effectively activate and trigger the biological cascades initiated by the mechano-sensing.

Morphometric and Nanomechanical Features of Erythrocytes Characteristic of Early Pregnancy Loss

Early pregnancy loss (EPL) is estimated to be between 15 and 20% of all adverse pregnancies. Approximately, half of EPL cases have no identifiable cause. Herein, we apply atomic force microscopy to evaluate the alteration of morphology and nanomechanics of erythrocytes from women with EPL with unknown etiology, as compared to healthy pregnant (PC) and nonpregnant women (NPC). Freshly isolated erythrocytes from women with EPL differ in both the roughness value (4.6 ± 0.3 nm, p < 0.05), and Young’s modulus (2.54 ± 0.6 MPa, p < 0.01) compared to the values for NPC (3.8 ± 0.4 nm and 0.94 ± 0.2 MPa, respectively) and PC (3.3 ± 0.2 nm and 1.12 ± 0.3 MPa, respectively). Moreover, we find a time-dependent trend for the reduction of the cells’ morphometric parameters (cells size and surface roughness) and the membrane elasticity—much faster for EPL than for the two control groups. The accelerated aging of EPL erythrocytes is expressed in faster morphological shape transformation and earlier occurrence of spiculated and spherical-shaped cells, reduced membrane roughness and elasticity with aging evolution. Oxidative stress in vitro contributed to the morphological cells’ changes observed for EPL senescent erythrocytes. The ultrastructural characteristics of cells derived from women with miscarriages show potential as a supplementary mark for a pathological state.

Ultrafiltration of α-Lactalbumin Protein: Acquaintance of the Filtration Performance by Membrane Structure and Surface Alteration

α-Lactalbumin is an essential protein with multiple roles in physiological and the nutritional functionalities, such as diabetic prevention, blood pressure stabilization, and cancer cell inhibition. In the present work, polyethersulfone (PES)-based membranes were developed by incorporating Pluronic F127 and carbon nanotubes with single- and multi-walled dimensions (Sw-Cnts and Mw-Cnts) as additives. The resulting membranes were evaluated for use in the filtration of α-lactalbumin protein solution. Four series of membranes, including PES pristine membrane, were fabricated via the phase inversion process. The characteristics of the membrane samples were analyzed in terms of morphology, membrane surface hydrophilicity and roughness, and surface chemistry. The characterization results show that the incorporation of additive increased the surface wettability by reducing the surface water contact angle from 80.4° to 64.1° by adding F127 and Mw-Cnt additives. The highest pure water permeability of 135 L/(m2·h·bar) was also exhibited by the PES/F127/Mw-Cnt membrane. The performance of the modified membranes was clearly better than the pristine PSF for α-lactalbumin solution filtration. The permeability of α-lactalbumin solution increased from 9.0 L/(m2·h·bar) for the pristine PES membrane to 10.5, 11.0 and 11.5 L/(m2·h·bar) for membranes loaded with Pluronic F127, Sw-Cnts, and Mw-Cnts, respectively. Those increments corresponded to 17, 22, and 28%. Such increments could be achieved without altering the α-lactalbumin rejections of 80%. Remarkably, the rejection for the membrane loaded with Sw-Cnts even increased to 89%.

Amyloid β peptide affects erythrocyte morphology: Role of intracellular signaling pathways

BACKGROUND

Circulating red blood cells (RBCs) undergo aging, a fundamental physiological phenomenon that regulates their turnover.

OBJECTIVE

Understanding the role of Aβ in the cross talk between cell signalling pathways and modulation of the cell structural and biomechanical properties occurring in RBCs during aging.

METHODS

The morphological pattern has been monitored using Atomic Force Microscopy (AFM) imaging and measuring the RBCs' plasma membrane roughness employed as a morphological parameter capable to provide information on the structure and integrity of the membrane-skeleton.

RESULTS

We show that treatment with Aβ accelerates the occurrence of morphological and biochemical aging markers in human RBC and influences the cell metabolism. Biochemical data demonstrate that contemporaneously to morphological alterations, Aβ triggers: (i) metabolic alterations and (ii) a complex signaling pathway involving caspase 3, protein kinase C and nitric oxide derived metabolites.

CONCLUSIONS

our study provides a comprehensive picture in which Aβ treatment of RBC induces changes in specific cell signalling events and/or metabolic pathways, in turns affecting the membrane-cytoskeleton interaction and the membrane integrity.

Gold nanoparticle uptake is enhanced by estradiol in MCF-7 breast cancer cells

Purpose: In the present study, we investigated the effects of 17β-estradiol (E₂) on membrane roughness and gold nanoparticle (AuNP) uptake in MCF-7 breast cancer cells. Methods: Estrogen receptor (ER)-positive breast cancer cells (MCF-7) were exposed to bare 20 nm AuNPs in the presence and absence of 1×10^-9 M E₂ for different time intervals for up to 24 hrs. The effects of AuNP incorporation and E₂ incubation on the MCF-7 cell surface roughness were measured using atomic force microscopy (AFM). Endocytic vesicle formation was studied using confocal laser scanning microscopy (CLSM). Finally, the results were confirmed by hyperspectral optical microscopy. Results: High-resolution AFM images of the surfaces of MCF-7 membranes (up to 250 nm²) were obtained. The incubation of cells for 12 hrs with AuNP and E₂ increased the cell membrane roughness by 95% and 30% compared with the groups treated with vehicle (ethanol) or AuNPs only, respectively. This effect was blocked by an ER antagonist (7α,17β-[9-[(4,4,5,5,5-Pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol [ICI] 182,780). Higher amounts of AuNPs were localized inside MCF-7 cells around the nucleus, even after 6 hrs of E₂ incubation, compared with vehicle-treated cells. Endolysosome formation was induced by E₂, which may be associated with an increase in AuNP-uptake. Conclusions: E₂ enhances AuNP incorporation in MCF-7 cells by modulating of plasma membrane roughness and inducing lysosomal endocytosis. These findings provide new insights into combined nanotherapies and hormone therapies for breast cancer.

Increasing roughness of the human breast cancer cell membrane through incorporation of gold nanoparticles

Gold nanoparticles (AuNPs) have been proposed for use in the treatment of different types of cancer, including breast cancer. At present, neither the mechanisms of AuNP interaction with the plasma membrane surface and their delivery and intracellular distribution in cancer cells nor their effect on the plasma membrane so as to allow cell incorporation of larger amounts of AuNPs is known. The objective of this work was to study the interaction of bare 20 nm diameter AuNPs with the plasma membrane of human MCF-7 breast cancer cells, as well as their uptake, intracellular distribution, and induction of changes on the cell surface roughness. The dynamics of intracellular incorporation and the distribution of AuNPs were observed by confocal laser scanning microscopy. Changes in roughness were monitored in synchronized MCF-7 cells by atomic force microscopy high-resolution imaging at 6 hour intervals for 24 hours during a single cell cycle. The results show that bare AuNPs are capable of emitting fluorescence at 626 nm, without the need for a fluorescent biomarker, which allows monitoring their uptake and intracellular distribution until they reach the nucleus. These results are correlated with changes in cell roughness, which significantly increases at 12 hours of incubation with AuNPs, when compared with control cells. The obtained data provide bases to understand molecular processes of the use of AuNPs in the treatment of different diseases, mainly breast cancer.

Binding equilibrium and kinetics of membrane-anchored receptors and ligands in cell adhesion: Insights from computational model systems and theory

The adhesion of cell membranes is mediated by the binding of membrane-anchored receptor and ligand proteins. In this article, we review recent results from simulations and theory that lead to novel insights on how the binding equilibrium and kinetics of these proteins is affected by the membranes and by the membrane anchoring and molecular properties of the proteins. Simulations and theory both indicate that the binding equilibrium constant [Formula: see text] and the on- and off-rate constants of anchored receptors and ligands in their 2-dimensional (2D) membrane environment strongly depend on the membrane roughness from thermally excited shape fluctuations on nanoscales. Recent theory corroborated by simulations provides a general relation between [Formula: see text] and the binding constant [Formula: see text] of soluble variants of the receptors and ligands that lack the membrane anchors and are free to diffuse in 3 dimensions (3D).