Endothelial cell function on 2D and 3D micro-fabricated polymer scaffolds: applications in cardiovascular tissue engineering.

Polymeric structures of a polylactide-polycaprolactone blend were micro-fabricated using the Pressure Assisted Microsyringe (PAM) system. Human umbilical vein endothelial cells were cultured on the scaffolds, and apoptosis, cell adhesion, proliferation and metabolism were evaluated. In addition, more specific indicators of endothelial cell function, namely nitric oxide and endothelin production, were also assessed. Thin films of the blend, as well as gelatine-coated glass slides (as controls) were used. The results show that as far as adhesion, apoptosis and metabolism are concerned, the scaffolds do not interfere with cell function compared with gelatin controls. However, the nitric oxide/endothelin ratio was higher than that observed on the gelatin films, suggesting that the scaffolds could be used for engineering small diameter blood vessels without risk of occlusion.

Design, preparation and testing of suitable probe-receptors for RNA biosensing.

Absolute measurements of a given RNA in a cheap, easy, rapid and reproducible manner using biosensors technology could overcome many of the operative and analytical limits of conventional molecular biology methods. To this end, an integrated approach for the design, synthesis, and connection of RNA probes to the transducing surface of a microgravimetric biosensor has been developed. Suitable probes to be used as the bioreceptors in RNA biosensor were successfully designed by using a purposely developed computational method whose selection criteria are based on the accessibility of target region to probe, on pairing stability of probe-target duplex and on the uniqueness of selected targets over all known expressed sequences from a genome data base. Automated chemical synthesis of selected probes was performed and the oligonucleotides produced were covalently conjugated to the sensing surface of a quartz microbalance. The microgravimetric sensor was tested in a flow chamber by measuring the variation of resonance frequency due to the binding of synthetic target substrates. Specific dose dependent binding was observed. Furthermore, the binding of a transcribed full-length mRNA substrate was successfully monitored under similar conditions.

Influence of chronic aerobic exercise on microcirculatory flow and nitric oxide in humans.

In the present study we assessed the effect of physical training on Laser Doppler skin flux (LDF) and nitric oxide (NO) release, before and after 3 min of brachial artery occlusion. To this end we performed laser Doppler measurements and the venous plasma assay of nitrite/nitrate (NOx) on 10 sedentary healthy subjects and 10 endurance athletes. The sedentary control subjects had lower basal and post reperfusion levels of NOx as compared to athletes (mean +/- SE: 27.8 +/- 3.5 vs. 33.2 +/- 3.4, 48.6 +/- 7.9 vs. 60.1 +/- 10.1 micromol/L; p < 0.05). LDF at baseline was not significantly different in the two groups (157.5 +/- 7.9 and 176.64 +/- 26.7 PU for sedentary subjects and athletes, respectively) while post ischemic LDF was significantly lower in nonathletic subjects than in athletes (209.9 +/- 13 and 343.8 +/- 21.3 PU, p < 0.001). In both groups the hyperaemic stimulus significantly increased LDF and NOx levels (p < 0.01 and p < 0.05, respectively). The flow reserve, estimated as peak/basal LDF, was significantly lower in control subjects than in athletes (1.34 +/- 0.2 and 2.32 +/- 0.9, respectively, p < 0.01). In athletes, as opposed to sedentary subjects, a direct correlation was found between plasma NOx concentration and LDF both in basal conditions (r = 0.92; p < 0.001), and during hyperaemia (r = 0.84; p < 0.01). In conclusion, compared to sedentary subjects, athletes had an enhanced nitric oxide release. Hyperaemia increased LDF and nitric oxide levels both in sedentary subjects and in athletes.

Langmuir-Blodgett films of antibodies as mediators of endothelial cell adhesion on polyurethanes.

The effect of endothelial cell adhesion on polyurethanes coated with Langmuir-Blodgett antibody films has been examined. The films were cross-linked with glutaraldehyde with the aim of providing a densely packed and covalently linked two-dimensional antibody network on the polyurethane surfaces. Our results demonstrate that although neither of the two polyurethanes examined were entirely suited to cellular adhesion, Langmuir-Blodgett antibody films, cross-linked with small concentrations of glutaraldehyde, are more suitable for endothelial cell adhesion than surfaces free of antibody.

Piezoelectric guidance channels enhance regeneration in the mouse sciatic nerve after axotomy.

Piezoelectric nerve guidance channels made of polyvinylidene fluoride (PVDF) were evaluated in a transected mouse sciatic nerve model. Poled PVDF channels were compared to unpoled PVDF channels after 4 and 12 weeks of implantation. In all animals, the proximal and distal nerve stumps were bridged by a continuous nerve cable. Nerves regenerated in poled channels contained a higher number of myelinated axons than those regenerated in unpoled channels at both time periods. We conclude that piezoelectric nerve guidance channels enhance peripheral nerve regeneration and provide a tool to investigate the influence of electrical activity on nerve regeneration.