Aligned biodegradable nanofibrous structure: a potential scaffold for blood vessel engineering

A unique biodegradable nanofibrous structure, aligned poly(L-lactid-co-epsilon-caprolactone) [P(LLA-CL)] (75:25) copolymer nanofibrous scaffold was produced by electrospinning. The diameter of the generated fibers was around 500 nm with an aligned topography which mimics the circumferential orientation of cells and fibrils found in the medial layer of a native artery. A favorable interaction between this scaffold with human coronary artery smooth muscle cells (SMCs) was demonstrated via MTS assay, phase contrast light microscopy, scanning electron microscopy, immunohistology assay and laser scanning confocal microscopy separately. Tissue culture polystyrene and plane solvent-cast P(LLA-CL) film were used as controls. The results showed that, the SMCs attached and migrated along the axis of the aligned nanofibers and expressed a spindle-like contractile phenotype; the distribution and organization of smooth muscle cytoskeleton proteins inside SMCs were parallel to the direction of the nanofibers; the adhesion and proliferation rate of SMCs on the aligned nanofibrous scaffold was significantly improved than on the plane polymer films. The above results strongly suggest that this synthetic aligned matrix combines with the advantages of synthetic biodegradable polymers, nanometer-scale dimension mimicking the natural ECM and a defined architecture replicating the in vivo-like vascular structure, may represent an ideal tissue engineering scaffold, especially for blood vessel engineering.

Physical activity and immune senescence in men

A cross-sectional survey examined whether habitual endurance exercisers retained a higher level of T cell function than sedentary individuals in old age. Subjects, all male, comprised 17 elderly runners, 16 young, and 19 elderly controls (mean ages +/- SD: 63.8 +/- 3.3, 23.6 +/- 1.6, and 65.8 +/- 3.5 yr, respectively), whose resting blood samples served for the immunological tests. Compared with the young subjects, both elderly groups had lower circulating CD3+ and CD8+ cell-counts (P = 0.029, P = 0.001, respectively), with a trend to a higher CD4/CD8 ratio, but higher percentages of activated CD3+, and "memory" CD4+ and CD8+ cells (all, P < 0.0001). Proliferative responses to phytohemagglutinin, pokeweed mitogen, and alloantigens were markedly reduced in the elderly (P < 0.001, and P = 0.024, respectively). IL-2 production tended to be decreased in the elderly sedentary subjects. However, natural killer cell activity and other cytokine production remained unchanged in the elderly sedentary subjects. Comparison between the active and sedentary elderly groups showed no differences in circulating counts of immunocompetent cells. However, the active elderly subjects demonstrated significantly greater proliferative responses to phytohemagglutinin ( P = 0.016) and to pokeweed mitogen (P = 0.011), and higher rates of IL-2 (P = 0.021), IFN-gamma (P = 0.015) and IL-4 production (P = 0.012). These results suggest that endurance training in later life is associated with a lesser age-related decline in certain aspects of circulating T cell function and related cytokine production.