Abstract In mineralized tissue the process of angiogenesis is required for normal osteogenesis during bone repair and in reconstructive and substitutive surgery, for proper biomaterial/tissue ...integration. Nanotechnologies have been proposed to improve the compatibility of biomaterials for use in orthopaedic and reconstructive surgery (e.g., nanocrystals). The aim of this study was to determine the effect of nanostructured hydroxyapatite (HA) on angiogenesis. Microvascular endothelial cell survival, proliferation and migration, crucial events in the angiogenic process, were evaluated together with cytoskeleton and biochemical signalling markers. Induction of migration, metalloproteinase (MMP-2) and focal adhesion Kinase (FAK) activity documented the ability of HA nanocrystals to stimulate capillary endothelium toward an angiogenic phenotype. HA concentrations, ranging from 2 to 10 μg/ml, promoted endothelium survival and proliferation, preserved αv β3 -integrin localization, stimulated β-actin reorganization and Akt phosphorylation (98% vs control). Immunoassays for key signalling pathways in angiogenesis (i.e., endothelial nitric oxide synthase (eNOS) and fibroblast growth factor-2 (FGF-2)) demonstrated that HA increased their expression. Moreover, quantitative RT-PCR and Western blotting analysis confirmed that HA nanocrystals exposure up-regulated FGF-2 mRNA by 6 fold and increased 18 kDa protein isoform by 40%. HA enhanced cell responsiveness to vascular endothelial growth factor (VEGF) in terms of NOS activity (1.5 fold over control), increasing the ability of microvascular endothelium to differentiate into capillary-like structures when grown in 3D fibrin gel. In conclusion our data document the proangiogenic properties of HA nanocrystals. This material stimulates endothelial cell functions and biochemical pathways to an extent similar to VEGF, and primes them to VEGF stimulation, leading to differentiation in pseudocapillary formations in 3D matrices.
The number of astronauts involved in long-lasting missions and extra-vehicular activities is going to increase in the future. Consequently, the chance of injury due to traumatic events or unexpected ...emergency surgery will also increase and medical evacuation times to earth will be prolonged. Hence, the need to address requirements for surgery and trauma care in non terrestrial environments will be a priority. Tissue repair in weightlessness should therefore be regarded as a major issue not enough studied to date. Wound healing is a complex multi-step process, crucial to the survival of the organism. It starts with an inflammatory phase followed by a remodelling phase. During repair, the extracellular matrix (ECM) is sequentially remodelled by the concerted action of different cell types, in order to rebuild a functional tissue. The available literature concerning wound healing with mechanical unloading presents controversial results. However, many studies indicate impairment of the healing processes. Here we present a study on the behaviour of cells involved in the remodelling phase of repair, e.g. fibroblasts and endothelial cells, in response to microgravity (
μg
). In particular, their adhesion/migration, cytoskeleton organization, production of ECM molecules and receptors have been investigated. Cell response to pulsed Nd:
YAG laser irradiation has also been investigated
in order to evaluate the possibility to use laser irradiation for counteracting the effect of
μg
on wound healing. In
μg
, we observed alterations in production/assembling of ECM molecules. Increased fibronectin (FN) and laminin (LM) could be the cause for impaired ECM rebuilding and altered cell adhesion/migration. Treatment with Nd:YAG laser pulses induced organized fibrillogenesis and favoured endothelial cell spreading and monolayer formation. These findings open the way for a better understanding of tissue repair mechanisms in space and future clinical applications on earth.
It is well known that endothelial cells (ECs), which play a major role in cardiovascular system functioning, are very sensitive to mechanical stimuli. It has been demonstrated that changes in ...inertial conditions (i.e. microgravity and hypergravity) can affect both phenotypic and genotypic expression in ECs. In this report we describe the effects of hypergravity on ECs isolated from bovine aorta (BAECs). ECs were repeatedly exposed to discontinuous hypergravity conditions (5 × 10 min at 10×
g
with 10 min at 1×
g
between sets), simulated in a hyperfuge. Then, cell morphology and metabolism were analyzed by autofluorescence techniques. The phenotypic expression of cytoskeleton constituents (
β
-actin, vimentin, tubulin), adhesion and survival signals (integrins), mediators of inflammation and angiogenesis was evaluated by immunocytofluorescence. Quantitative PCR (Q-PCR) with Low Density Arrays (LDAs) was used to evaluate modifications in gene expression. After hypergravity exposure, no significant changes were observed in cell morphology and energy metabolism. Cells remained adherent to the substratum, but integrin distribution was modified. Accordingly, the cytoskeletal network reorganized, documenting cell activation. There was a reduction in expression of genes controlling vasoconstriction and inflammation. Proapoptotic signals were downregulated. On the whole, the results documented that hypergravity exposure maintained EC survival and function by activation of adaptive mechanisms.
Cardiovascular diseases are major health problems in astronauts and pilots. The basic problem in cardiovascular diseases is the loss of function by vascular endothelium. It has been demonstrated that ...changes in inertial conditions (i.e. hypo- and hypergravity) can affect both phenotypic and genotypic expression in endothelial cells. This report describes the effects observed in endothelial cells from coronary post-capillary venules after repeated exposures to hypergravity conditions, alternating with recovery periods. The results showed changes in gene expression, cell energy metabolism, morphology and cytoskeleton organization.PUBLICATION ABSTRACT
Dipeptidyl peptidase 4 (DPP-4) is an enzyme that is produced by endothelial cells in different districts and circulates in plasma. Patients with type 2 diabetes show a reduction in active ...Glucagon-Like Peptide-1 (GLP-1) that could be due to impairment of secretion or its degradation or both. GLP-1 is rapidly inactivated in vivo, mainly by the DPP-4. Some authors suggest that Metformin has no direct inhibitory effect on DPP-4 activity and that Metformin and the other biguanides enhance GLP-1 secretion; others suggest a possible role of Metformin in the inhibition of the DPP-4 activity. In order to better elucidate the role of insulin sensitizers on the modulation of GLP-1 circulating levels, DPP-4 activity and mRNA expression were measured in cultured human aortic endothelial cells (HAEC) and human microvascular dermal endothelial cells (HMVEC) exposed to high glucose, Metformin and Rosiglitazone. Present data show that hyperglycemia is capable of increasing in a significant manner the DPP-4 activity only in microvascular endothelial cells. Rosiglitazone is able to modulate in a negative manner the expression of DPP-4 but not its activity in macrovascular endothelial cells, while at 24 h of exposure it is able to increase significantly DPP-4 activity but not its expression in microvascular endothelial cells. Metformin at 48 h only in microvascular endothelial cells is able to reduce in a significant manner (
p
= 0.01) the activity of DPP-4 but not its expression. The modulation of DPP-4 is site specific.
Background and Aims. The secretion of several adipocytokines, such as adiponectin, retinol-binding protein 4 (RBP4), adipocyte fatty acid binding protein (aFABP), and visfatin, is altered in subjects ...with abdominal adiposity; these endocrine alterations could contribute to increased cardiovascular risk. The aim of the study was to assess the relationship among adiponectin, RBP4, aFABP, and visfatin, and incident cardiovascular disease. Methods and Results. A case-control study, nested within a prospective cohort, on 2945 subjects enrolled for a diabetes screening program was performed. We studied 18 patients with incident fatal or nonfatal IHD (Ischemic Heart Disease) or CVD (Cerebrovascular Disease), compared with 18 matched control subjects. Circulating adiponectin levels were significantly lower in cases of IHD with respect to controls. Circulating RBP4 levels were significantly increased in CVD and decreased in IHD with respect to controls. Circulating aFABP4 levels were significantly increased in CVD, while no difference was associated with IHD. Circulating visfatin levels were significantly lower in cases of both CVD and IHD with respect to controls, while no difference was associated with CVD. Conclusions. The present study confirms that low adiponectin is associated with increased incidents of IHD, but not CVD, and suggests, for the first time, a major effect of visfatin, aFABP, and RBP4 in the development of cardiovascular disease.
Glucagon-like peptide-1 (GLP-1), a meal-stimulated gastrointestinal insulinotropic hormone inactivated by dipeptidyl peptidase-IV (DPP-IV), is reduced in type 2 diabetic patients. The present study ...shows that 2-week exposure of human glomerular endothelial cells to high glucose (22
mM) determines a highly significant increase in DPP-IV activity and mRNA expression, which cannot be entirely accounted for by hyperosmolarity. On the other hand, incubation of purified DPP-IV in a buffer solution added with high glucose does not affect enzyme activity. These results suggest that high glucose increases expression and activity of DPP-IV, possibly contributing to GLP-1 reduction in type 2 diabetic patients.
Electrohydrodimerization (EHD) of ethylcinnamate (EC) on mercury takes place both from hydrotropic solutions of tetraethylammonium-
p-toluenesulphonate (TEA-PTS) and from dilute aqueous solutions of ...the strong surfactant Triton X-100. In both cases the one-electron reduction wave due to hydrodimer formation satisfies the requirements for a rate-determining homogeneous coupling of the electrochemically generated anion radicals. The kinetics of EC EHD on liquid gallium is identical with that on mercury at the same temperature of 31°C in hydrotropic solutions of TEA-PTS; conversely, in aqueous Triton X-100 it is faster than on mercury and satisfies the requirements for a rate-determining heterogeneous radical-radical coupling. This behaviour is explained by a stronger adsorptivity of EC and its intermediate reduction products on gallium than on mercury, so that Triton X-100 does not succeed in displacing these species completely from the electrode surface. The general trend consisting in a higher adsorptivity of organic compounds with conjugated double bonds and/or aromatic rings on gallium than on mercury is explained on the basis of the difference in hydrophilicity between these two metals.
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