Daily egg consumption in hyperlipidemic adults - Effects on endothelial function and cardiovascular risk

<p>Abstract</p> <p>Background</p> <p>Limiting consumption of eggs, which are high in cholesterol, is generally recommended to reduce risk of cardiovascular disease. However, recent evidence suggests that dietary cholesterol has limited influence on serum cholesterol or cardiac risk.</p> <p>Objective</p> <p>To assess the effects of egg consumption on endothelial function and serum lipids in hyperlipidemic adults.</p> <p>Methods</p> <p>Randomized, placebo-controlled crossover trial of 40 hyperlipidemic adults (24 women, 16 men; average age = 59.9 ± 9.6 years; weight = 76.3 ± 21.8 kilograms; total cholesterol = 244 ± 24 mg/dL). In the acute phase, participants were randomly assigned to one of the two sequences of a single dose of three medium hardboiled eggs and a sausage/cheese breakfast sandwich. In the sustained phase, participants were then randomly assigned to one of the two sequences of two medium hardboiled eggs and 1/2 cup of egg substitute daily for six weeks. Each treatment assignment was separated by a four-week washout period. Outcome measures of interest were endothelial function measured as flow mediated dilatation (FMD) and lipid panel.</p> <p>Results</p> <p>Single dose egg consumption had no effects on endothelial function as compared to sausage/cheese (0.4 ± 1.9 vs. 0.4 ± 2.4%; <it>p </it>= 0.99). Daily consumption of egg substitute for 6 weeks significantly improved endothelial function as compared to egg (1.0 ± 1.2% vs. -0.1 ± 1.5%; <it>p </it>< 0.01) and lowered serum total cholesterol (-18 ± 18 vs. -5 ± 21 mg/dL; <it>p </it>< 0.01) and LDL (-14 ± 20 vs. -2 ± 19 mg/dL; <it>p </it>= 0.01). Study results (positive or negative) are expressed in terms of change relative to baseline.</p> <p>Conclusions</p> <p>Egg consumption was found to be non-detrimental to endothelial function and serum lipids in hyperlipidemic adults, while egg substitute consumption was beneficial.</p

Stroke Repair via Biomimicry of the Subventricular Zone

Stroke is among the leading causes of death and disability worldwide, 85% of which are ischemic. Current stroke therapies are limited by a narrow effective therapeutic time and fail to effectively complete the recovery of the damaged area. Magnetic resonance imaging of the subventricular zone (SVZ) following infarct/stroke has allowed visualization of new axonal connections and projections being formed, while new immature neurons migrate from the SVZ to the peri-infarct area. Such studies suggest that the SVZ is a primary source of regenerative cells for the repair and regeneration of stroke-damaged neurons and tissue. Therefore, the development of tissue engineered scaffolds that serve as a bioreplicative SVZ niche would support the survival of multiple cell types that reside in the SVZ. Essential to replication of the human SVZ microenvironment is the establishment of microvasculature that regulates both the healthy and stroke-injured blood–brain barrier, which is dysregulated poststroke. In order to reproduce this niche, understanding how cells interact in this environment is critical, in particular neural stem cells, endothelial cells, pericytes, ependymal cells, and microglia. Remodeling and repair of the matrix-rich SVZ niche by endogenous reparative mechanisms may then support functional recovery when enhanced by an artificial niche that supports the survival and proliferation of migrating vascular and neuronal cells. Critical considerations to mimic this area include an understanding of resident cell types, delivery method, and the use of biocompatible materials. Controlling stem cell survival, differentiation, and migration are key factors to consider when transplanting stem cells. Here, we discuss the role of the SVZ architecture and resident cells in the promotion and enhancement of endogenous repair mechanisms. We elucidate the interplay between the extracellular matrix composition and cell interactions prior to and following stroke. Finally, we review current cell and neuronal niche biomimetic materials that allow for a tissue-engineered approach in order to promote structural and functional restoration of neural circuitry. By creating an artificial mimetic SVZ, tissue engineers can strive to facilitate tissue regeneration and functional recovery

Biomimetic, ultrathin and elastic hydrogels regulate human neutrophil extravasation across endothelial-pericyte bilayers

<div><p>The vascular basement membrane—a thin, elastic layer of extracellular matrix separating and encasing vascular cells—provides biological and mechanical cues to endothelial cells, pericytes, and migrating leukocytes. In contrast, experimental scaffolds typically used to replicate basement membranes are stiff and bio-inert. Here, we present thin, porated polyethylene glycol hydrogels to replicate human vascular basement membranes. Like commercial transwells, our hydrogels are approximately 10μm thick, but like basement membranes, the hydrogels presented here are elastic (E: 50-80kPa) and contain a dense network of small pores. Moreover, the inclusion of bioactive domains introduces receptor-mediated biochemical signaling. We compare elastic hydrogels to common culture substrates (E: >2GPa) for human endothelial cell and pericyte monolayers and bilayers to replicate postcapillary venules <i>in vitro</i>. Our data demonstrate that substrate elasticity facilitates differences in vascular phenotype, supporting expression of vascular markers that are increasingly replicative of venules. Endothelial cells differentially express vascular markers, like EphB4, and leukocyte adhesion molecules, such as ICAM-1, with decreased mechanical stiffness. With porated PEG hydrogels we demonstrate the ability to evaluate and observe leukocyte recruitment across endothelial cell and pericyte monolayers and bilayers, reporting that basement membrane scaffolds can significantly alter the rate of vascular migration in experimental systems. Overall, this study demonstrates the creation and utility of a new and accessible method to recapture the mechanical and biological complexity of human basement membranes <i>in vitro</i>.</p></div

Vascular cell response to TNFα-activation on porated PEG gels.

<p>(a) EC (top), PC (middle) and EC/PC (bottom) cell layers in profile stained for ICAM-1 (green) and DAPI (blue) on 20kDa gels. Scale bars are ten microns. (b-d) Flow cytometry results of ECs stained for ICAM-1 (b), VCAM-1 (c), and E-selectin (d) under control and TNFα-activated conditions on RGD-coated glass (E>2GPa), 10kDa (E: 83.8kPa), or 20kDa (E: 54.7kPa) hydrogels. (e-g) Flow cytometry of PCs stained for ICAM-1 (b), VCAM-1 (c), and E-selectin (d) under control and TNFα-activated conditions on RGD-coated glass (E>2GPa), 10kDa (E: 83.8kPa), or 20kDa (E: 54.7kPa) hydrogels.</p

EC phenotype is modulated by substrate stiffness.

<p>(a-c) Brightfield images of ECs cultured on RGD-coated glass (E>2GPa), 10kDa (E: 83.8kPa), or 20kDa (E: 54.7kPa) hydrogels. Scale bars are 80 microns. (d) Quantification of cell size across all three substrates. **p<0.01, ****p<0.0001 as determined by one-way ANOVA. (e-h) Phalloidin (red) and DAPI (blue) staining on sub-confluent ECs on glass (e), 10kDa (f), and 20kDa (g) gels and quantification of the actin intensity (h). *p<0.05, **p<0.01, ****p<0.0001 as determined by unpaired t-test. Intensity of 10kDa and 20kDa images augmented to increase staining visibility. (i-l) VE-cadherin (green) and DAPI (blue) staining on ECs on glass (i), 10kDa (j), and 20kDa (k) gels and quantification of the junctional width (l); *p<0.05 as determined by one-way ANOVA. (m-o) EphB4 (green) and DAPI (blue) staining on ECs on glass (m), 10kDa (n), and 20kDa (o) gels with representative flow cytometry dot plots shown below each image. Quantification of the intensity of expression (p); *p<0.05 as determined by unpaired t-test. (q-s) Connexin40 (green) and DAPI (blue) staining on ECs on glass (q), 10kDa (r), and 20kDa (s) gels with representative flow cytometry dot plots shown below each image. Quantification of the stain intensity by flow cytometry; *p<0.05 by unpaired t-test (t). Scale bars in (e-s) are ten microns.</p

Zinc oxide micro-needles introduce pores into PEG hydrogels.

<p>(a-b) Images of commercial TWs (a-i) and porated PEG hydrogels in TW casing (b-i). SEM micrographs of TWs (a-ii), 10kDa (b-ii), and 20kDa (b-iii) porated PEG hydrogels; scale bars: 5 microns. (c) Hydrogel thickness as determined by OCT. Whiskers denote minimum and maximum value; there is no statistical difference between 10kDa and 20kDa hydrogels. (d) Young’s modulus of 10kDa and 20kDa porated PEG hydrogels. Whiskers denote minimum and maximum value; *p<0.05.</p

Neutrophil capture on with EC or PC monolayers or EC/PC bilayers.

<p>(a) Quantification of neutrophil capture within EC monolayers, PC monolayers, or EC/PC bilayers on transwells (TWs), 10kDa hydrogels, or 20kDa hydrogels under quiescent or TNFα-activated conditions. *p<0.05, **p<0.01, ***p<0.001, and ****p<0.0001 when compared to TWs under the same culture conditions. Unless noted, changes between scaffolds are not significant. (b) Confocal microscopy results of neutrophils interacting with cellular layers on 20kDa hydrogel scaffolds. <i>i and ii</i>. Projection (i; * indicates three distinct neutrophils) and profile (ii; *neutrophils, dashed line outlines EC nuclei layer) of an EC monolayer with neutrophils. <i>iii</i>. Profile of PCs (dashed line outlines PC nucleus) and neutrophils (*denotes neutrophils). <i>iv</i>. EC/PC bilayer (apical layer: EC; basal layer: PC; dashed line outlines cell nuclei) and neutrophils (*denotes neutrophils). Scale bars are 10 microns.</p

Neutrophil interactions with porated PEG hydrogels.

<p>(a) Neutrophil capture in transwells (TWs) and hydrogels without or with RGD. *p<0.05 for control v. IL-8 on the same scaffold, #p<0.05, ###p<0.001 for comparisons between the same condition on scaffolds +/- RGD. All statistical differences determined by a two-way ANOVA. Changes are not significant unless otherwise denoted. (b-g) SEM micrographs of human neutrophils on TWs (b-c), 10kDa porated gels (d-e), or 20kDa gels (f-g) under control (left) or IL-8 (right) conditions. Scale bars are 5 microns.</p

PC phenotype on glass and PEG hydrogels.

<p>(a-c) Brightfield images of PCs cultured on RGD-coated glass (E>2GPa), 10kDa (E: 83.8kPa), or 20kDa (E: 54.7kPa) hydrogels. Scale bars are 80 microns. (d) Quantification of cell size across all three substrates. *p<0.05, ***p<0.001 as determined by one-way ANOVA. (e-h) Phalloidin (red) and DAPI (blue) staining on sub-confluent PCs on glass (e), 10kDa (f), and 20kDa (g) gels and quantification of the actin intensity (h). ****p<0.0001 as determined by unpaired t-test. (i-l) NG2 (red) and DAPI (blue) staining on PCs on glass (i), 10kDa (j), and 20kDa (k) gels with representative flow cytometry dot plots shown below each image. Quantification of intensity by flow cytometry (l). (m-o) PDGFRβ (green) and DAPI (blue) staining on PCs on glass (m), 10kDa (n), and 20kDa (o) gels with representative flow cytometry dot plots shown below each image. Quantification of the intensity of expression (p). (q-s) Connexin43 (green) and DAPI (blue) staining on PCs on glass (q), 10kDa (r), and 20kDa (s) gels with representative flow cytometry dot plots shown below each image. Quantification of staining intensity by flow cytometry (t). Scale bars in fluorescent images are 10 microns.</p