Sex and diet-dependent gene alterations in human and rat brains with a history of nicotine exposure.

Introduction: Chronic nicotine exposure induces changes in the expression of key regulatory genes associated with metabolic function and neuronal alterations in the brain. Many bioregulatory genes have been associated with exposure to nicotine, but the modulating effects of sex and diet on gene expression in nicotine-exposed brains have been largely unexplored. Both humans and rodents display motivation for nicotine use and the emergence of withdrawal symptoms during abstinence. Research comparing pre-clinical models with human subjects provides an important opportunity to understand common biomarkers of the harmful effects of nicotine as well as information that may help guide the development of more effective interventions for nicotine cessation. Methods: Human postmortem dorsolateral prefrontal cortex (dLPFC) tissue BA9 was collected from female and male subjects, smokers and non-smokers (N = 12 per group). Rat frontal lobes were collected from female and male rats that received a regular diet (RD) or a high-fat diet (HFD) (N = 12 per group) for 14 days following implantation of a osmotic mini-pump (Alzet) that delivered nicotine continuously. Controls (control-s) received a sham surgical procedure. RNA was extracted from tissue from human and rat samples and reversed-transcribed to cDNA. Gene expression of CHRNA10 (Cholinergic receptor nicotinic alpha 10), CERKL (Ceramide Kinase-Like), SMYD1 (SET and MYD Domin Containing 1), and FA2H (Fatty Acid 2-Hydrolase) in humans was compared to rats in each subset of groups and quantified by qPCR methods. Additionally, protein expression of FA2H was analyzed by immunohistochemistry (IHC) in human dLPFC. Results: Humans with a history of smoking displayed decreased CHRNA10 (p = 0.0005), CERKL (p ≤ 0.0001), and SMYD1 (p = 0.0005) expression and increased FA2H (p = 0.0097) expression compared to non-smokers (p < 0.05). Similar patterns of results were observed in nicotine exposed vs. control rats. Interestingly, sex-related differences in gene expression for CERKL and FA2H were observed. In addition, ANCOVA analysis showed a significant effect of nicotine in a sex-different manner, including an increase in CERKL in male and female rats with RD or HFD. In rats exposed to an HFD, FA2H gene expression was lower in nicotine-treated rats compared to RD rats treated with nicotine. Protein expression of FA2H (p = 0.001) by IHC was significantly higher in smokers compared to non-smokers. Conclusion: These results suggest that a history of long-term nicotine exposure in humans alters the expression of sphingolipid metabolism-related (CERKL, SMYD1, and FA2H) and neuronal (CHRNA10) marker genes similarly as compared to rats. Sex- and diet-dependent differences appear in nicotine-exposed rats, critical in regulating sphingolipid metabolism and nicotinic acetylcholine receptors. This research enhances the construct validity of rat models of nicotine usage by showing a similar pattern of changes in gene expression in human subjects with a smoking history.

Hydrogel scaffolds with elasticity-mimicking embryonic substrates promote cardiac cellular network formation.

Hydrogels are a class of biomaterials used for a wide range of biomedical applications, including as a three-dimensional (3D) scaffold for cell culture that mimics the extracellular matrix (ECM) of native tissues. To understand the role of the ECM in the modulation of cardiac cell function, alginate was used to fabricate crosslinked gels with stiffness values that resembled embryonic (2.66 ± 0.84 kPa), physiologic (8.98 ± 1.29 kPa) and fibrotic (18.27 ± 3.17 kPa) cardiac tissues. The average pore diameter and hydrogel swelling were seen to decrease with increasing substrate stiffness. Cardiomyocytes cultured within soft embryonic gels demonstrated enhanced cell spreading, elongation, and network formation, while a progressive increase in gel stiffness diminished these behaviors. Cell viability decreased with increasing hydrogel stiffness. Furthermore, cells in fibrotic gels showed enhanced protein expression of the characteristic cardiac stress biomarker, Troponin-I, while reduced protein expression of the cardiac gap junction protein, Connexin-43, in comparison to cells within embryonic gels. The results from this study demonstrate the role that 3D substrate stiffness has on cardiac tissue formation and its implications in the development of complex matrix remodeling-based conditions, such as myocardial fibrosis.

Alginate Hydrogels with Embedded ZnO Nanoparticles for Wound Healing Therapy.

INTRODUCTION: In this in-vitro study, we designed a 3D printed composite of zinc oxide (ZnO) nanoparticles (NPs) with photocatalytic activities encapsulated within hydrogel (alginate) constructs, for antibacterial purposes applicable towards wound healing. We primarily sought to confirm the mechanical properties and cell compatibility of these ZnO NP infused scaffolds. METHODS: The antibacterial property of the ZnO NPs was confirmed by hydroxyl radical generation using ultraviolet (U.V.) photocatalysis. Titanium dioxide (TiO2), a well-known antibacterial compound, was used as a positive control (1% w/v) for the ZnO NP-based alginate constructs and their antibacterial efficacies compared. Among the ZnO group, 3D printed gels containing 0.5% and 1% w/v of ZnO were analyzed and compared with manually casted samples via SEM, swelling evaluation, and rheological analysis. Envisioning an in-vivo application for the 3D printed ZnO NP-based alginates, we studied their antibacterial properties by bacterial broth testing, cytocompatibility via live/dead assay, and moisture retention capabilities utilizing a humidity sensor. RESULTS: 3D printed constructs revealed significantly greater pore sizes and enhanced structural stability compared to manually casted samples. For all samples, the addition of ZnO or TiO2 resulted in significantly stiffer gels in comparison with the alginate control. Bacterial resistance testing on Staphylococcus epidermidis indicated the addition of ZnO NPs to the gels decreased bacterial growth when compared to the alginate only gels. Cell viability of STO-fibroblasts was not adversely affected by the addition of ZnO NPs to the alginate gels. Furthermore, the addition of increasing doses of ZnO NPs to the alginate demonstrated increased humidity retention in gels. DISCUSSION: The customization of 3D printed alginates containing antibacterial ZnO NPs leads to an alternative that allows accessible mobility of molecular exchange required for improving chronic wound healing. This scaffold can provide a cost-effective and durable antibacterial treatment option.

A Comparative Study in the Printability of a Bioink and 3D Models Across Two Bioprinting Platforms.

In this study, we used an alginate-gelatin bioink to design and print 3D constructs with lattice, honeycomb and fibrous bundle patterns. These designs were printed using a small-scale laboratory printer, at first and later translated to a larger scale, high throughput-printing platform. A comparative analysis of the structures printed using two dissimilar platforms using gross morphologic evaluation, scanning electron microscopy and swelling assay confirmed our hypothesis that a design printed using a small-scale laboratory bioprinter for optimization of bioink composition and printing parameters can be successfully translated into a large scale-printing platform for high throughput printing of constructs. Since the designs for printing were implemented using a software which was common across both printers, this endpoint was feasible. The only difference in printing parameters resulted from variation in extrusion pressure which was due to a significant difference in barrel size used across both printers (3 ml versus 30 ml), while all other parameters stayed the same. Although the scaffolds were not bioprinted with cells, in future we will investigate how cell viability can be differentially regulated by the variation of extrusion pressure across both platforms.

Fabrication of Surfactant-Dispersed HiPco Single-Walled Carbon Nanotube-Based Alginate Hydrogel Composites as Cellular Products.

In this study, we designed, synthesized, and characterized ultrahigh purity single-walled carbon nanotube (SWCNT)-alginate hydrogel composites. Among the parameters of importance in the formation of an alginate-based hydrogel composite with single-walled carbon nanotubes, are their varying degrees of purity, their particulate agglomeration and their dose-dependent correlation to cell viability, all of which have an impact on the resultant composite's efficiency and effectiveness towards cell-therapy. To promote their homogenous dispersion by preventing agglomeration of the SWCNT, three different surfactants-sodium dodecyl sulfate (SDS-anionic), cetyltrimethylammonium bromide (CTAB-cationic), and Pluronic F108 (nonionic)-were utilized. After mixing of the SWCNT-surfactant with alginate, the mixtures were cross-linked using divalent calcium ions and characterized using Raman spectroscopy. Rheometric analysis showed an increase in complex viscosity, loss, and storage moduli of the SWCNT composite gels in comparison with pure alginate gels. Scanning electron microscopy revealed the presence of a well-distributed porous structure, and all SWCNT-gel composites depicted enhanced electrical conductivity with respect to alginate gels. To characterize their biocompatibility, cardiomyocytes were cultured atop these SWCNT-gels. Results comprehensively implied that Pluronic F108 was most efficient in preventing agglomeration of the SWCNTs in the alginate matrix, leading to a stable scaffold formation without posing any toxicity to the cells.