Reliable, standardized measurements for cell mechanical properties.

Atomic force microscopy (AFM) has become indispensable for studying biological and medical samples. More than two decades of experiments have revealed that cancer cells are softer than healthy cells (for measured cells cultured on stiff substrates). The softness or, more precisely, the larger deformability of cancer cells, primarily independent of cancer types, could be used as a sensitive marker of pathological changes.

Uptake of platelets by cancer cells and recycling of the platelet protein CD42a.

Background: It is well accepted that the bidirectional crosstalk between platelets and cancer cells promotes tumorigenesis and metastasis. In an early step, cancer cells trigger platelet granule and extracellular vesicle release that is needed to facilitate cancer cell survival in circulation.

Objectives: To discover the early crosstalk of cancer cells and platelets.

Quantification of heparin's antimetastatic effect by single-cell force spectroscopy.

In circulation, cancer cells induce platelet activation, leading to the formation of a cancer cell-encircling platelet cloak which facilitates each step of the metastatic cascade. Since cancer patients treated with the anticoagulant heparin showed reduced metastasis rates and improved survival, it is supposed that heparin suppresses the cloak's formation by inhibiting the interaction between platelet's adhesion molecule P-selectin with its ligands on cancer cells. To quantify this heparin effect, we developed a single-cell force spectroscopy approach and quantified the adhesion (maximum adhesion force [F ] and detachment work [W ]) between platelets and human non-small cell lung cancer cells (A549).

Endothelial EphB4 maintains vascular integrity and transport function in adult heart.

The homeostasis of heart and other organs relies on the appropriate provision of nutrients and functional specialization of the local vasculature. Here, we have used mouse genetics, imaging and cell biology approaches to investigate how homeostasis in the adult heart is controlled by endothelial EphB4 and its ligand ephrin-B2, which are known regulators of vascular morphogenesis and arteriovenous differentiation during development. We show that inducible and endothelial cell-specific inactivation of in adult mice is compatible with survival, but leads to rupturing of cardiac capillaries, cardiomyocyte hypertrophy, and pathological cardiac remodeling.

Signals of the Neuropilin-1-MET Axis and Cues of Mechanical Force Exertion Converge to Elicit Inflammatory Activation in Coherent Endothelial Cells.

The neuropilin-1 (NRP1)-MET signaling axis regulates the motility of individual endothelial cells (ECs). It is unknown how this signaling pathway affects the endothelial barrier in coherent ECs forming a tight monolayer. We hypothesized that it is involved both in modulation of the endothelial barrier and in EC activation.

Fifteen years of Servitude et Grandeur to the application of a biophysical technique in medicine: The tale of AFMBioMed.

AFMBioMed is the founding name under which international conferences and summer schools are organized around the application of atomic force microscopy in life sciences and nanomedicine. From its inception at the Atomic Energy Commission in Marcoule near 2004 to its creation in 2007 and to its 10th anniversary conference in Krakow, a brief narrative history of its birth and rise will demonstrate how and what such an organization brings to laboratories and the AFM community. With the current planning of the next AFMBioMed conference in Münster in 2019, it will be 15 years of commitment to these events.

Measuring the Elastic Properties of Living Cells.

Cell's elasticity is an integrative parameter summarizing the biophysical outcome of many known and unknown cellular processes. This includes intracellular signaling, cytoskeletal activity, changes of cell volume and morphology, and many others. Not only intracellular processes defines a cell's elasticity but also environmental factors like their biochemical and biophysical surrounding.

The anti-adhesive effect of glycoclusters on Pseudomonas aeruginosa bacteria adhesion to epithelial cells studied by AFM single cell force spectroscopy.

The human opportunistic pathogen Pseudomonas aeruginosa (PA) is responsible for chronic infections of the respiratory epithelium in cystic fibrosis patients. PA takes advantage of an arsenal of virulence factors to infect and colonize human lungs. Among them, the lectin LecA favours epithelium invasion by interacting with host cell globotriaosylceramide (Gb3).

K3.1 channel inhibition leads to an ICAM-1 dependent increase of cell-cell adhesion between A549 lung cancer and HMEC-1 endothelial cells.

Early metastasis leads to poor prognosis of lung cancer patients, whose 5-year survival rate is only 15%. We could recently show that the Ca sensitive K channel K3.1 promotes aggressive behavior of non-small cell lung cancer (NSCLC) cells and that it can serve as a prognostic marker in NSCLC.

Standardized Nanomechanical Atomic Force Microscopy Procedure (SNAP) for Measuring Soft and Biological Samples.

We present a procedure that allows a reliable determination of the elastic (Young's) modulus of soft samples, including living cells, by atomic force microscopy (AFM). The standardized nanomechanical AFM procedure (SNAP) ensures the precise adjustment of the AFM optical lever system, a prerequisite for all kinds of force spectroscopy methods, to obtain reliable values independent of the instrument, laboratory and operator. Measurements of soft hydrogel samples with a well-defined elastic modulus using different AFMs revealed that the uncertainties in the determination of the deflection sensitivity and subsequently cantilever's spring constant were the main sources of error.

Cystic fibrosis transmembrane conductance regulator is involved in polyphenol-induced swelling of the endothelial glycocalyx.

Unlabelled: Previous studies show that polyphenol-rich compounds can induce a swelling of the endothelial glycocalyx (eGC). Our goal was to reveal the mechanism behind the eGC-swelling. As polyphenols are potent modulators of fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel, the hypothesis was tested whether polyphenol-induced increase in CFTR activity is responsible for the eGC-swelling.

ECM stiffness regulates glial migration in Drosophila and mammalian glioma models.

Cell migration is an important feature of glial cells. Here, we used the Drosophila eye disc to decipher the molecular network controlling glial migration. We stimulated glial motility by pan-glial PDGF receptor (PVR) activation and identified several genes acting downstream of PVR.

Paracellular transport through healthy and cystic fibrosis bronchial epithelial cell lines--do we have a proper model?

It has been reported recently that the cystic fibrosis transmembrane conductance regulator (CFTR) besides transcellular chloride transport, also controls the paracellular permeability of bronchial epithelium. The aim of this study was to test whether overexpressing wtCFTR solely regulates paracellular permeability of cell monolayers. To answer this question we used a CFBE41o- cell line transfected with wtCFTR or mutant F508del-CFTR and compered them with parental line and healthy 16HBE14o- cells.

Hyaluronan export through plasma membranes depends on concurrent K+ efflux by K(ir) channels.

Hyaluronan is synthesized within the cytoplasm and exported into the extracellular matrix through the cell membrane of fibroblasts by the MRP5 transporter. In order to meet the law of electroneutrality, a cation is required to neutralize the emerging negative hyaluronan charges. As we previously observed an inhibiting of hyaluronan export by inhibitors of K(+) channels, hyaluronan export was now analysed by simultaneously measuring membrane potential in the presence of drugs.

Transient P2X7 receptor activation triggers macrophage death independent of Toll-like receptors 2 and 4, caspase-1, and pannexin-1 proteins.

The function of P2X(7) receptors (ATP-gated ion channels) in innate immune cells is unclear. In the setting of Toll-like receptor (TLR) stimulation, secondary activation of P2X(7) ion channels has been linked to pro-caspase-1 cleavage and cell death. Here we show that cell death is a surprisingly early triggered event.

Nanomechanics of human adipose-derived stem cells: small GTPases impact chondrogenic differentiation.

Objectives: Human adipose-derived stem cells (ASCs) show gene expression of chondrogenic markers after three-dimensional cultivation. However, hypertrophy and osteogenic transdifferentiation are still limiting clinical applications. The aim of this study was to investigate the impact of small GTPases (Rac1 and RhoA) on transforming growth factor (TGF)-β1-mediated chondrogenic differentiation of ASCs and compare it with BMP-2-induced hypertrophy, by assessing effects on intracellular and extracellular matrix.

Recovery of ΔF508-CFTR function by analogs of hyaluronan disaccharide.

We recently discovered that hyaluronan was exported from fibroblasts by MRP5 and from epithelial cells by cystic fibrosis (CF) transmembrane conductance regulator (CFTR) that was known as a chloride channel. On this basis we developed membrane permeable analogs of hyaluronan disaccharide as new class of compounds to modify their efflux. We found substances that activated hyaluronan export from human breast cancer cells.

Paracellular permeability of bronchial epithelium is controlled by CFTR.

In normal airway epithelium, the cystic fibrosis transmembrane conductance regulator (CFTR) transports Cl(-) ions to the apical surface of the epithelium paralleled by the flow of water through transcellular and paracellular pathways. The hypothesis was tested whether CFTR not only regulates the transcellular but also the paracellular shunt pathway. Therefore, we performed measurements of transepithelial electrical resistance (TER) and paracellular (14)C-mannitol permeability in wtCFTR (16HBE14o(-)) and delF508-CFTR (CFBE41o(-)) expressing human bronchial epithelial cells.

Salt overload damages the glycocalyx sodium barrier of vascular endothelium.

Sodium overload stiffens vascular endothelial cells in vitro and promotes arterial hypertension in vivo. The hypothesis was tested that the endothelial glycocalyx (eGC), a mesh of anionic biopolymers covering the surface of the endothelium, participates in the stiffening process. By using a mechanical nanosensor, mounted on an atomic force microscope, height (∼400 nm) and stiffness (∼0.

Normal and pathological erythrocytes studied by atomic force microscopy.

Erythrocytes (red blood cells, RBCs) are the most common type of blood cells in vertebrates. Many diseases and dysfunctions directly affect their structure and function. Employing the atomic force microscope (AFM) physical, chemical, and biological/physiological properties of RBCs can be studied even under near-physiological conditions.

Formation of cysts by principal-like MDCK cells depends on the synergy of cAMP- and ATP-mediated fluid secretion.

It has been suggested that more than 70% of the renal cysts in patients with autosomal dominant polycystic kidney disease (ADPKD) arise from the collecting duct and that within this segment cysts originate almost exclusively from principal rather than intercalated cells. The mechanisms for this predisposition of principal cells have so far remained elusive. We, therefore, used Madin-Darby canine kidney (MDCK) subclones resembling principal cells and alpha-intercalated cells in a three-dimensional in vitro model to determine differences in cystogenesis and cyst growth, including the response to cyclic adenosine monophosphate (cAMP) elevation and the dependence on ATP signaling.

C-reactive protein makes human endothelium stiff and tight.

Elevation of C-reactive protein (CRP) in human blood accompanies inflammatory processes, including cardiovascular diseases. There is increasing evidence that the acute-phase reactant CRP is not only a passive marker protein for systemic inflammation but also affects the vascular system. Further, CRP is an independent risk factor for atherosclerosis and the development of hypertension.