Mathematical Modeling of Oxygen Transfer in Porous Scaffolds for Stem Cell Growth: The Effects of Porosity, Cell Type, Scaffold Architecture and Cell Distribution

Oxygen plays a key role in human mesenchymal stem cell growth. Without adequate oxygen (hypoxic condition), cells are not able to survive, proliferate, and migrate. The objective of the present study is to investigate oxygen transfer through the cell-seeded scaffolds stored in static or dynamic bioreactors using a mathematical model. The effects of porosity, cell type, scaffold architecture and cell distribution as potential effective parameters on oxygen transfer kinetics were examined. The results suggest the substantial effect of porosity and cell type on the oxygen concentration within the scaffold compared to scaffold architecture (homogeneous vs. gradient). The obtained data show that the direction of oxygen transfer in deep regions with dead cells changes over time and reverse mass transfer allows the cells to nourish from both top and bottom layers. Finally, the extent of oxygen transfer in static bioreactors/cultures was compared to dynamic ones. The results show that dynamic bioreactors have a better performance and are more efficient for oxygen transfer

In Vitro Cytotoxicity and Setting Time Assessment of Calcium-Enriched Mixture Cement, Retro Mineral Trioxide Aggregate and Mineral Trioxide Aggregate

Introduction: The present study sought to evaluate and compare biocompatibility and setting time of Retro mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) and Angelus MTA. Methods and Materials: CEM cement, Angelus MTA and Retro MTA were assessed in set and fresh states. Extracts transformed to each cavity of three 24-well plates in which 1×104 cell were seeded into each well 24 h earlier. All specimens were incubated in a humidified incubator with 5% CO2 at 37°C. Mosmann’s tetrazolium toxicity (MTT) assay was used to determine in vitro cytotoxicity on L929 mouse fibroblast cell line. Cell viability was determined at 1, 24, and 72 h after exposure. The initial setting time was measured by 113.4 g Gilmore needle testing. Then, final setting times were assessed by the 456.5 g Gilmore needle. Data comparisons were performed using the analysis of variance (ANOVA) and Tukey's post hoc test (α=0.05). Results: All groups in both forms indicated higher cell vitality compared to positive control group (P<0.001). After 24 h, the set Retro MTA showed better biocompatibility compared to set CEM and set Angelus MTA (P<0.001). Retro MTA showed significantly lower initial and final setting time compared to CEM and Angelus MTA (P<0.001). Conclusion: Our results indicated the good cell viability values of Retro MTA and relatively short period of setting time. It seems a promising alternative material in clinical situations where accelerated setting is required. However, more clinical and in vivo investigations are needed for a clear decision making.Keywords: Biocompatibility; Calcium-Enriched Mixture; Mineral Trioxide Aggregate; Retro MTA; Setting Tim

Collagenous Matrix Supported by A 3D-Printed Scaffold for Osteogenic Differentiation of Dental Pulp Cells

Objective A systematic characterization of hybrid scaffolds, fabricated based on combinatorial additive manufacturing technique and freeze-drying method, is presented as a new platform for osteoblastic differentiation of dental pulp cells (DPCs). Methods The scaffolds were consisted of a collagenous matrix embedded in a 3D-printed beta-tricalcium phosphate (β-TCP) as the mineral phase. The developed construct design was intended to achieve mechanical robustness owing to 3D-printed β-TCP scaffold, and biologically active 3D cell culture matrix pertaining to the Collagen extracellular matrix. The β-TCP precursor formulations were investigated for their flow-ability at various temperatures, which optimized for fabrication of 3D printed scaffolds with interconnected porosity. The hybrid constructs were characterized by 3D laser scanning microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and compressive strength testing. Results The in vitro characterization of scaffolds revealed that the hybrid β-TCP/Collagen constructs offer superior DPCs proliferation and alkaline phosphatase (ALP) activity compared to the 3D-printed β-TCP scaffold over three weeks. Moreover, it was found that the incorporation of TCP into the Collagen matrix improves the ALP activity. Significance The presented results converge to suggest the developed 3D-printed β-TCP/Collagen hybrid constructs as a new platform for osteoblastic differentiation of DPCs for craniomaxillofacial bone regeneration

Vision, challenges and opportunities for a Plant Cell Atlas

With growing populations and pressing environmental problems, future economies will be increasingly plant-based. Now is the time to reimagine plant science as a critical component of fundamental science, agriculture, environmental stewardship, energy, technology and healthcare. This effort requires a conceptual and technological framework to identify and map all cell types, and to comprehensively annotate the localization and organization of molecules at cellular and tissue levels. This framework, called the Plant Cell Atlas (PCA), will be critical for understanding and engineering plant development, physiology and environmental responses. A workshop was convened to discuss the purpose and utility of such an initiative, resulting in a roadmap that acknowledges the current knowledge gaps and technical challenges, and underscores how the PCA initiative can help to overcome them.</jats:p

Cancer cell detection using electrochemical nanobiosensor based on graphene / gold nanoparticle

Introduction: Nowadays, early cancer detection and effective treatment is crucial for improved prognosis and cancer management. In particular, the accurate qualitative detection of cancer cells represents a critical step in cancer diagnosis. The aim of this study was to examine Cancer cell detection using electrochemical nanobiosensor based on graphene / gold nanoparticle. Materials and Methods: Modified graphene oxide/gold nanoparticle electrodes were employed to increase the sensitivity of human breast cancer MCF-7 cells detection, using CD44 biomarker. Frist the electrodes were modified with graphene, then gold nanoparticles were sediment on graphene-modified electrode. Then CD44 monoclonal antibody conjugated on the surface of gold nanoparticles, on graphene-modified electrode. Finally, the performance of the fabricated biosensors were investigated by using a common reference electrode composed of silver-silver chloride and a common platinum counter electrode at different antigen concentrations with the buffer and serum. Results: The proposed electrochemical cytosensor delivered a high sensitivity with the average of 1.12 &mu;A / cells ml-1, and a low detection limit of 6 cells. Conclusion: These results indicate that the cytosensor has great potential in diagnosis of cancer

Investigating the protective effects of cinnamon bark hydroalcoholic extract on the inhibition of liver damage induced by rifampin in male Wistar rats

Introduction: Rifampin is one of the common drugs used to treat tuberculosis and is considered a strong toxic agent for the liver. The aim of this study is to investigate the effects of cinnamon extract administration on rifampin-induced hepatotoxicity in rats. Materials and methods: In this experimental study, 60 male Wistar rats were randomly divided into 6 groups. Liver damage and induction of oxidative stress were caused by administration of 80 mg/kg/day rifampin. Different doses of cinnamon extract (50, 100 and 200 mg/kg) were administered to sick mice by daily gavage in three experimental groups. Liver damage caused by rifampin was evaluated by examining serum biochemical factors as well as the amount of reactive oxygen species, glutathione, antioxidant capacity, lipid peroxidation and histopathological changes in liver tissue. Data analysis was done using Prism version 6 software and one-way analysis of variance and Tukey's post hoc test. Results: The administration of rifampin at the rate of 80 mg/kg for 21 consecutive days caused liver damage (P<0.05). On the other hand, administration of different doses of cinnamon extract could significantly improve the liver damage caused by rifampin consumption (P<0.05) Discussion and conclusion: According to the results of this study, cinnamon extract with antioxidant properties protects the liver against oxidative damage caused by rifampin. These healing effects were shown in the form of reduction of liver damage markers in serum, reduction of oxidative stress markers and improvement of liver tissue damage

A genosensor for detection of HTLV-I based on photoluminescence quenching of fluorescent carbon dots in presence of iron magnetic nanoparticle-capped Au

Abstract Carbon dots and Fe3O4@Au were synthesized to develop a new biosensor to detect DNA target. We investigated the photoluminescence property of carbon dots (CDs) in the presence of Fe3O4-capped Au (Fe3O4@Au). Firstly, we designed two dedicated probes for unique long sequence region of human T-lymphotropic virus type 1 genome. One of the probes was covalently bound to the CDs. In the absence of target, CDs-probe was adsorbed on the surface of Fe3O4@Au through two possible mechanisms, leading to quenching the fluorescence emission of CDs. The fluorescence emission of CDs was recovered in the presence of target since double-stranded DNA cannot adsorb on the Fe3O4@Au. Also, Fe3O4@Au can adsorb the unhybridized oligonucleotides and improves the accuracy of detection. The specificity of the proposed biosensor was confirmed by BLAST search and assessed by exposing the biosensor to other virus targets. The experimental detection limit of the biosensor was below 10 nM with linear range from 10 to 320 nM

Incorporation of Functionalized Reduced Graphene Oxide/magnesium Nanohybrid to Enhance the Osteoinductivity Capability of 3D Printed Calcium Phosphate-based Scaffolds

Improving bone regeneration is one of the most pressing problems facing bone tissue engineering (BTE) which can be tackled by incorporating different biomaterials into the fabrication of the scaffolds. The present study aims to apply the 3D-printing and freeze-drying methods to design an ideal scaffold for improving the osteogenic capacity of Dental pulp stem cells (DPSCs). To achieve this purpose, hybrid constructs consisted of 3D-printed Beta-tricalcium phosphate (β-TCP)-based scaffolds filled with freeze-dried gelatin/reduced graphene oxide-Magnesium-Arginine (GRMA) matrix were fabricated through a novel green method. The effect of different concentrations of Reduced graphene oxide-Magnesium-Arginine (RMA) (0, 0.25% and 0.75%wt) on the morphology, mechanical properties, and biological activity of the 3D scaffolds were completely evaluated. Our findings show that the incorporation of RMA hybrid into the scaffold can remarkably enhance its mechanical features and improve cell proliferation and differentiation simultaneously. Of all scaffolds, β-TCP/0.25GRMA showed not only the highest ALP activity and cell proliferation after 14 days but it up-regulated bone-related genes and proteins (COL-I, RUNX2, OCN). Hence, the fabricated 3D printed β-TCP/0.25GRMA porous scaffolds can be considered as a high-potential candidate for BTE