Ultrastructural features mirror metabolic derangement in human endothelial cells exposed to high glucose.

High glucose-induced endothelial dysfunction is the early event that initiates diabetes-induced vascular disease. Here we employed Cryo Soft X-ray Tomography to obtain three-dimensional maps of high D-glucose-treated endothelial cells and their controls at nanometric spatial resolution. We then correlated ultrastructural differences with metabolic rewiring. While the total mitochondrial mass does not change, high D-glucose promotes mitochondrial fragmentation, as confirmed by the modulation of fission-fusion markers, and dysfunction, as demonstrated by the drop of membrane potential, the decreased oxygen consumption and the increased production of reactive oxygen species. The 3D ultrastructural analysis also indicates the accumulation of lipid droplets in cells cultured in high D-glucose. Indeed, because of the decrease of fatty acid ß-oxidation induced by high D-glucose concentration, triglycerides are esterified into fatty acids and then stored into lipid droplets. We propose that the increase of lipid droplets represents an adaptive mechanism to cope with the overload of glucose and associated oxidative stress and metabolic dysregulation.

Cluster-Assembled Zirconia Substrates Accelerate the Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells.

Due to their high mechanical strength and good biocompatibility, nanostructured zirconia surfaces (ns-ZrOx) are widely used for bio-applications. Through supersonic cluster beam deposition, we produced ZrOx films with controllable roughness at the nanoscale, mimicking the morphological and topographical properties of the extracellular matrix. We show that a 20 nm ns-ZrOx surface accelerates the osteogenic differentiation of human bone marrow-derived MSCs (bMSCs) by increasing the deposition of calcium in the extracellular matrix and upregulating some osteogenic differentiation markers. bMSCs seeded on 20 nm ns-ZrOx show randomly oriented actin fibers, changes in nuclear morphology, and a reduction in mitochondrial transmembrane potential when compared to the cells cultured on flat zirconia (flat-ZrO2) substrates and glass coverslips used as controls. Additionally, an increase in ROS, known to promote osteogenesis, was detected after 24 h of culture on 20 nm ns-ZrOx. All the modifications induced by the ns-ZrOx surface are rescued after the first hours of culture. We propose that ns-ZrOx-induced cytoskeletal remodeling transmits signals generated by the extracellular environment to the nucleus, with the consequent modulation of the expression of genes controlling cell fate.

The Interplay between TRPM7 and MagT1 in Maintaining Endothelial Magnesium Homeostasis.

The transient receptor potential cation channel subfamily M member 7 (TRPM7) is an ubiquitous channel fused to an α-kinase domain involved in magnesium (Mg) transport, and its level of expression has been proposed as a marker of endothelial function. To broaden our present knowledge about the role of TRPM7 in endothelial cells, we generated stable transfected Human Endothelial Cells derived from the Umbilical Vein (HUVEC). TRPM7-silencing HUVEC maintain the actin fibers' organization and mitochondrial network. They produce reduced amounts of reactive oxygen species and grow faster than controls. Intracellular Mg concentration does not change in TRPM7-silencing or -expressing HUVEC, while some differences emerged when we analyzed intracellular Mg distribution. While the levels of the plasma membrane Mg transporter Solute Carrier family 41 member 1 (SLC41A1) and the mitochondrial channel Mrs2 remain unchanged, the highly selective Magnesium Transporter 1 (MagT1) is upregulated in TRPM7-silencing HUVEC through transcriptional regulation. We propose that the increased amounts of MagT1 grant the maintenance of intracellular Mg concentrations when TRPM7 is not expressed in endothelial cells.

The presence of BBB hastens neuronal differentiation of cerebral organoids - The potential role of endothelial derived BDNF.

Despite remaining the best in vitro model to resemble the human brain, a weakness of human cerebral organoids is the lack of the endothelial component that in vivo organizes in the blood brain barrier (BBB). Since the BBB is crucial to control the microenvironment of the nervous system, this study proposes a co-culture of BBB and cerebral organoids. We utilized a BBB model consisting of primary human brain microvascular endothelial cells and astrocytes in a transwell system. Starting from induced Pluripotent Stem Cells (iPSCs) we generated human cerebral organoids which were then cultured in the absence or presence of an in vitro model of BBB to evaluate potential effects on the maturation of cerebral organoids. By morphological analysis, it emerges that in the presence of the BBB the cerebral organoids are better organized than controls in the absence of the BBB. This effect might be due to Brain Derived Neurotrophic Factor (BDNF), a neurotrophic factor released by the endothelial component of the BBB, which is involved in neurodevelopment, neuroplasticity and neurosurvival.

The Presence of Blood-Brain Barrier Modulates the Response to Magnesium Salts in Human Brain Organoids.

Magnesium (Mg) is fundamental in the brain, where it regulates metabolism and neurotransmission and protects against neuroinflammation. To obtain insights into the molecular basis of Mg action in the brain, we investigated the effects of Mg in human brain organoids, a revolutionary 3D model to study neurobiology and neuropathology. In particular, brain organoids derived from human induced pluripotent stem cells were cultured in the presence or in the absence of an in vitro-generated blood-brain barrier (BBB), and then exposed to 1 or 5 mM concentrations of inorganic and organic Mg salts (Mg sulphate (MgSO4); Mg pidolate (MgPid)). We evaluated the modulation of NMDA and GABAergic receptors, and BDNF. Our data suggest that the presence of the BBB is essential for Mg to exert its effects on brain organoids, and that 5 mM of MgPid is more effective than MgSO4 in increasing the levels of GABA receptors and BDNF, and decreasing those of NMDA receptor. These results might illuminate novel pathways explaining the neuroprotective role of Mg.

Magnesium and the Brain: A Focus on Neuroinflammation and Neurodegeneration.

Magnesium (Mg) is involved in the regulation of metabolism and in the maintenance of the homeostasis of all the tissues, including the brain, where it harmonizes nerve signal transmission and preserves the integrity of the blood-brain barrier. Mg deficiency contributes to systemic low-grade inflammation, the common denominator of most diseases. In particular, neuroinflammation is the hallmark of neurodegenerative disorders. Starting from a rapid overview on the role of magnesium in the brain, this narrative review provides evidences linking the derangement of magnesium balance with multiple sclerosis, Alzheimer's, and Parkinson's diseases.

Vitamin D Prevents High Glucose-Induced Lipid Droplets Accumulation in Cultured Endothelial Cells: The Role of Thioredoxin Interacting Protein.

Vitamin D (VitD) exerts protective effects on the endothelium, which is fundamental for vascular integrity, partly by inhibiting free radical formation. We found that VitD prevents high glucose-induced Thioredoxin Interacting Protein (TXNIP) upregulation. Increased amounts of TXNIP are responsible for the accumulation of reactive oxygen species and, as a consequence, of lipid droplets. This is associated with increased amounts of triglycerides as the result of increased lipogenesis and reduced fatty acid oxidation. Remarkably, VitD rebalances the redox equilibrium, restores normal lipid content, and prevents the accumulation of lipid droplets. Our results highlight TXNIP as one of the targets of VitD in high glucose-cultured endothelial cells and shed some light on the protective effect of VitD on the endothelium.

A Comparison of Doxorubicin-Resistant Colon Cancer LoVo and Leukemia HL60 Cells: Common Features, Different Underlying Mechanisms.

Chemoresistance causes cancer relapse and metastasis, thus remaining the major obstacle to cancer therapy. While some light has been shed on the underlying mechanisms, it is clear that chemoresistance is a multifaceted problem strictly interconnected with the high heterogeneity of neoplastic cells. We utilized two different human cell lines, i.e., LoVo colon cancer and promyelocytic leukemia HL60 cells sensitive and resistant to doxorubicin (DXR), largely used as a chemotherapeutic and frequently leading to chemoresistance. LoVo and HL60 resistant cells accumulate less reactive oxygen species by differently modulating the levels of some pro- and antioxidant proteins. Moreover, the content of intracellular magnesium, known to contribute to protect cells from oxidative stress, is increased in DXR-resistant LoVo through the upregulation of MagT1 and in DXR-resistant HL60 because of the overexpression of TRPM7. In addition, while no major differences in mitochondrial mass are observed in resistant HL60 and LoVo cells, fragmented mitochondria due to increased fission and decreased fusion are detected only in resistant LoVo cells. We conclude that DXR-resistant cells evolve adaptive mechanisms to survive DXR cytotoxicity by activating different molecular pathways.

Unveiling the basis of antiretroviral therapy-induced osteopenia: the effects of Dolutegravir, Darunavir and Atazanavir on osteogenesis.

OBJECTIVES: Osteopenia is frequent in HIV-infected patients treated with antiretroviral therapy (ART) and has been linked to increased osteoclastogenesis. Little is known about the effects of ART on osteogenesis. DESIGN: We investigated the effect on human mesenchymal stem cells (hMSC) and osteoblasts of Darunavir and Dolutegravir, the most highly used as anchor drugs within a three-drug regimen, and Atazanavir, which was widely utilized in the past. RESULTS: We found that Atazanavir and Dolutegravir delay the osteogenic differentiation of hMSC, impair the activity of osteoblasts and inhibit their conversion into osteocytes, whereas Darunavir exerts no effect. CONCLUSION: Atazanavir and Dolutegravir impair osteogenesis. It is essential to diagnose impaired osteogenesis early and to devise effective therapeutic interventions to preserve bone health in ART-treated HIV patients, putting it in the context of a correct antiretroviral combination.

Scalable Microgravity Simulator Used for Long-Term Musculoskeletal Cells and Tissue Engineering.

We introduce a new benchtop microgravity simulator (MGS) that is scalable and easy to use. Its working principle is similar to that of random positioning machines (RPM), commonly used in research laboratories and regarded as one of the gold standards for simulating microgravity. The improvement of the MGS concerns mainly the algorithms controlling the movements of the samples and the design that, for the first time, guarantees equal treatment of all the culture flasks undergoing simulated microgravity. Qualification and validation tests of the new device were conducted with human bone marrow stem cells (bMSC) and mouse skeletal muscle myoblasts (C2C12). bMSC were cultured for 4 days on the MGS and the RPM in parallel. In the presence of osteogenic medium, an overexpression of osteogenic markers was detected in the samples from both devices. Similarly, C2C12 cells were maintained for 4 days on the MGS and the rotating wall vessel (RWV) device, another widely used microgravity simulator. Significant downregulation of myogenesis markers was observed in gravitationally unloaded cells. Therefore, similar results can be obtained regardless of the used simulated microgravity devices, namely MGS, RPM, or RWV. The newly developed MGS device thus offers easy and reliable long-term cell culture possibilities under simulated microgravity conditions. Currently, upgrades are in progress to allow real-time monitoring of the culture media and liquids exchange while running. This is of particular interest for long-term cultivation, needed for tissue engineering applications. Tissue grown under real or simulated microgravity has specific features, such as growth in three-dimensions (3D). Growth in weightlessness conditions fosters mechanical, structural, and chemical interactions between cells and the extracellular matrix in any direction.

Headaches and Magnesium: Mechanisms, Bioavailability, Therapeutic Efficacy and Potential Advantage of Magnesium Pidolate.

Magnesium deficiency may occur for several reasons, such as inadequate intake or increased gastrointestinal or renal loss. A large body of literature suggests a relationship between magnesium deficiency and mild and moderate tension-type headaches and migraines. A number of double-blind randomized placebo-controlled trials have shown that magnesium is efficacious in relieving headaches and have led to the recommendation of oral magnesium for headache relief in several national and international guidelines. Among several magnesium salts available to treat magnesium deficiency, magnesium pidolate may have high bioavailability and good penetration at the intracellular level. Here, we discuss the cellular and molecular effects of magnesium deficiency in the brain and the clinical evidence supporting the use of magnesium for the treatment of headaches and migraines.

Endothelial Hyper-Permeability Induced by T1D Sera Can be Reversed by iNOS Inactivation.

Type 1 Diabetes Mellitus (T1D) is associated with accelerated atherosclerosis that is responsible for high morbidity and mortality. Endothelial hyperpermeability, a feature of endothelial dysfunction, is an early step of atherogenesis since it favours intimal lipid uptake. Therefore, we tested endothelial leakage by loading the sera from T1D patients onto cultured human endothelial cells and found it increased by hyperglycaemic sera. These results were phenocopied in endothelial cells cultured in a medium containing high concentrations of glucose, which activates inducible nitric oxide synthase with a consequent increase of nitric oxide. Inhibition of the enzyme prevented high glucose-induced hyperpermeability, thus pointing to nitric oxide as the mediator involved in altering the endothelial barrier function. Since nitric oxide is much higher in sera from hyperglycaemic than normoglycaemic T1D patients, and the inhibition of inducible nitric oxide synthase prevents sera-dependent increased endothelial permeability, this enzyme might represent a promising biochemical marker to be monitored in T1D patients to predict alterations of the vascular wall, eventually promoting intimal lipid accumulation.

Mitophagy contributes to endothelial adaptation to simulated microgravity.

Exposure to real or simulated microgravity is sensed as a stress by mammalian cells, which activate a complex adaptive response. In human primary endothelial cells, we have recently shown the sequential intervention of various stress proteins which are crucial to prevent apoptosis and maintain cell function. We here demonstrate that mitophagy contributes to endothelial adaptation to gravitational unloading. After 4 and 10 d of exposure to simulated microgravity in the rotating wall vessel, the amount of BCL2 interacting protein 3, a marker of mitophagy, is increased and, in parallel, mitochondrial content, oxygen consumption, and maximal respiratory capacity are reduced, suggesting the acquisition of a thrifty phenotype to meet the novel metabolic challenges generated by gravitational unloading. Moreover, we suggest that microgravity induced-disorganization of the actin cytoskeleton triggers mitophagy, thus creating a connection between cytoskeletal dynamics and mitochondrial content upon gravitational unloading.

Magnesium and the blood-brain barrier in vitro: effects on permeability and magnesium transport.

The blood-brain barrier (BBB) tightly regulates the homeostasis of the central nervous system, and its dysfunction has been described in several neurological disorders. Since magnesium exerts a protective effect in the brain, we assessed whether supraphysiological concentrations of different magnesium salts modulate the permeability and magnesium transport in in vitro models of rat and human BBB. Among various formulations tested, magnesium pidolate was the most efficient in reducing the permeability and in enhancing magnesium transport through the barrier. We then compared magnesium pidolate and magnesium sulfate, a widely used salt in experimental models and in clinical practice. Magnesium pidolate performs better than sulfate also in preventing lipopolysaccharide-induced damage to in vitro generated BBB. We conclude that magnesium pidolate emerges as an interesting alternative to sulfate to protect BBB and maintain correct intracerebral concentrations of magnesium.

The dynamic adaptation of primary human endothelial cells to simulated microgravity.

Culture of human endothelial cells for 10 d in real microgravity onboard the International Space Station modulated more than 1000 genes, some of which are involved in stress response. On Earth, 24 h after exposure to simulated microgravity, endothelial cells up-regulate heat shock protein (HSP) 70. To capture a broad view of endothelial stress response to gravitational unloading, we cultured primary human endothelial cells for 4 and 10 d in the rotating wall vessel, a U.S. National Aeronautics and Space Administration-developed surrogate system for benchtop microgravity research on Earth. We highlight the crucial role of the early increase of HSP70 because its silencing markedly impairs cell survival. Once HSP70 up-regulation fades away after 4 d of simulated microgravity, a complex and articulated increase of various stress proteins (sirtuin 2, paraoxonase 2, superoxide dismutase 2, p21, HSP27, and phosphorylated HSP27, all endowed with cytoprotective properties) occurs and counterbalances the up-regulation of the pro-oxidant thioredoxin interacting protein (TXNIP). Interestingly, TXNIP was the most overexpressed transcript in endothelial cells after spaceflight. We conclude that HSP70 up-regulation sustains the initial adaptive response of endothelial cells to mechanical unloading and drives them toward the acquisition of a novel phenotype that maintains cell viability and function through the sequential involvement of different stress proteins.-Cazzaniga, A., Locatelli, L., Castiglioni, S., Maier, J. A. M. The dynamic adaptation of primary human endothelial cells to simulated microgravity.

Reactive oxygen species are implicated in altering magnesium homeostasis in endothelial cells exposed to high glucose.

Transient Receptor Potential Melastatin (TRPM)7 is important in maintaining the intracellular homeostasis of magnesium (Mg), which is instrumental for vital cellular functions. Since the upregulation of TRPM7 has been proposed as a marker of endothelial dysfunction, we evaluated the effects of high glucose, which markedly impacts endothelial performance, on TRPM7 and intracellular Mg homeostasis in human macrovascular endothelial cells. We show that glucose-induced free radicals increase the amounts of TRPM7 as well as total intracellular magnesium. On the contrary, the highly selective Mg transporter MagT1 is not modulated by high glucose, hydrogen peroxide and low extracellular magnesium. We conclude that in endothelial cells high glucose alters Mg homeostasis through the upregulation of TRPM7.