Caloric restriction has consistently been shown to extend life span and ameliorate aging-related diseases. These effects may be due to diet-induced reactive oxygen species acting to up-regulate sirtuins and related protective pathways, which research suggests may be partially inhibited by dietary anti-oxidant supplementation. Because caloric restriction is not sustainable long term for most humans, we investigated an alternative dietary approach, intermittent fasting (IF), which is proposed to act on similar biological pathways. We hypothesized that a modified IF diet, where participants maintain overall energy balance by alternating between days of fasting (25% of normal caloric intake) and feasting (175% of normal), would increase expression of genes associated with aging and reduce oxidative stress and that these effects would be suppressed by anti-oxidant supplementation. To assess the tolerability of the diet and to explore effects on biological mechanisms related to aging and metabolism, we recruited a cohort of 24 healthy individuals in a double-crossover, double-blinded, randomized clinical trial. Study participants underwent two 3-week treatment periods-IF and IF with anti-oxidant (vitamins C and E) supplementation. We found strict adherence to study-provided diets and that participants found the diet tolerable, with no adverse clinical findings or weight change. We detected a marginal increase (2.7%) in SIRT3 expression due to the IF diet, but no change in expression of other genes or oxidative stress markers analyzed. We also found that IF decreased plasma insulin levels (1.01 μU/mL). Although our study suggests that the IF dieting paradigm is acceptable in healthy individuals, additional research is needed to further assess the potential benefits and risks.

Background Herein we describe a small-diameter vascular graft constructed from rolled human amniotic membrane (hAM), with in vitro evaluation and subsequent in vivo assessment of its mechanical and initial biological viability in the early post-implantation period. This approach for graft construction allows for customization of graft dimensions, with wide-ranging potential clinical applicability as a non-autologous, allogeneic, cell-free graft material. Methods and Results Acellular hAM were rolled into layered conduits (3.2-mm diameter) that were bound with fibrin and lyophilized. In vitro analysis Constructs were seeded with human smooth muscle cells (SMC) and cultured under controlled arterial hemodynamic conditions. SMC were shown to adhere to, proliferate within, and remodel the scaffold over a four-week culture period. At the end of the culture period, there was histologic and biomechanical evidence of graft wall layer coalescence. In vivo analysis The acellular hAM conduits were surgically implanted as arterial interposition grafts into the carotid arteries of immunocompetent rabbits. Grafts demonstrated patency over four weeks (n=3) with no hyperacute rejection or thrombotic occlusion. Explants displayed histologic evidence of active cellular remodeling, with endogenous cell repopulation of the graft wall concurrent with degradation of initial graft material. Cells were shown to align circumferentially to resemble a vascular medial layer. Conclusions The vascular grafts were shown to provide a supportive scaffold allowing for cellular infiltration and remodeling by host cell populations in vivo. Using this approach, “off-the-shelf” vascular grafts can be created with specified diameters and wall thicknesses to satisfy specific anatomical requirements in diverse patient populations.