Nanocomposite scaffold seeded with mesenchymal stem cells for bone repair

The mechanical property of bone tissue scaffolds is one of the most important aspects in bone tissue engineering that has remained problematic. In our previous study, we fabricated a three‐dimensional scaffold from nano‐hydroxyapatite/gelatin (nHA/Gel) and investigated its efficiency in promoting bone regeneration both in vitro and in vivo. In the present study, the effect of adding silicon carbide (SiC) on the mechanical and biological behaviors of the nHA/Gel/SiC and bone regeneration in vivo were determined. nHA and SiC were synthesized and characterized by the X‐ray diffraction pattern and transmission electron microscope image. Layer solvent casting, freeze drying, and lamination techniques were applied to prepare these scaffolds. Then, the biocompatibility and cell adhesion behavior of the synthesized nHA/Gel/SiC scaffolds were investigated. For in vivo studies, rats were categorized into three groups: blank defect, blank scaffold, and rat bone marrow mesenchymal stem cells (rBM‐MSCs)/scaffold. After 1, 4, and 12 weeks post‐injury, the rats were sacrificed and the calvaria were harvested. Sections with a thickness of 5 µm thickness were prepared and stained with hematoxylin–eosin and Masson's Trichrome, and immunohistochemistry was performed. Our results showed that SiC effectively increased the mechanical properties of the nHA/Gel/SiC scaffold. No significant differences were observed in biocompatibility, cell adhesion, and cytotoxicity of the nHA/Gel/SiC in comparison with the nHA/Gel nanocomposite. Based on histological and immunohistochemical studies, both osteogenesis and collagenization were significantly higher in the rBM‐MSCs/scaffold group, quantitatively and qualitatively. The present study strongly suggests the potential of SiC as an alternative strategy to improve the mechanical and biological properties of bone tissue engineering scaffolds, and shows that the pre‐seeded nHA/Gel/SiC scaffold with rBM‐MSCs improves osteogenesis in the engineered bone implant.     

Relationship between myocardial bridge compression severity and haemodynamic perturbations

Objectives: This study aims to examine the alteration in coronary haemodynamics with increasing the severity of vessel compression caused by myocardial bridging (MB).

Methods: Angiography and intravascular ultrasound were performed in 10 patients with MB with varying severities of systolic compression in the left anterior descending (LAD) artery. Computer models of MB were developed and transient computational fluid dynamics simulations were performed to derive distribution of blood residence time and shear stress.

Results: With increasing the severity of bridge compression, a decreasing trend was observed in the shear stress over proximal segment whereas an increasing trend was found in the shear stress over bridge segment. When patients were divided into 2 groups based on the average systolic vessel compression in the whole cohort (%CR_ave = 27.38), patients with bridges with major systolic compression (>%CR_ave) had smaller shear stress and higher residence time in the proximal segment compared to those with bridges with minor systolic compression (<%CR_ave) (0.37?±?0.23 vs 0.69?±?0.29?Pa and 0.0037?±?0.0069 vs 0.022?±?0.0094?s). In contrast, patients with bridges with major systolic compression had greater shear stress in the bridge segment compared to those with bridges with minor systolic compression (2.49?±?2.06 vs 1.13?±?0.89?Pa). No significant difference was found in the distal shear stress of patients with bridges with major and minor systolic compression.

Conclusion: Our findings revealed a direct relationship between the severity of systolic compression of MB and haemodynamic perturbations in the proximal segment such that the increased systolic vessel compression was associated with decreased shear stress and increased blood residence time.     

Ischemia-reperfusion and immediate T cell responses

The pathogenesis of ischemia-reperfusion injury (IRI) is complex and not well understood. Inflammation plays an important role in IRI, with involvement of leukocytes, adhesion molecules, chemokines and cytokines. Emerging data suggest a role of T cells as mediators of IRI both in renal and extra-renal organs. Divergent roles of T cell subsets have also been elucidated, suggesting a more complicated role of T cells in the different phases of IRI. This review presents recent evidence from various animal models that advances our understanding of the role T cells play in IRI. These findings entertain the possibility of using immunotherapeutic agents for the prevention and treatment of IRI.     

Use of Coupled Al-Ag Bimetallic Cylindrical Nanoparticles to Improve the Photocurrent of a Thin-Film Silicon Solar Cell

In this paper, cylindrical shape coupled bimetallic plasmonic nanoparticles (NPs) were used to improve the performance of a thin-film silicon solar cell. Our design is based on the appropriate selection of the composition and morphology of the NPs to reach a cell with excellent optical properties. The specific interaction between the incident light and bimetallic NPs helps us to design better solar absorbers. Here, the FDTD method was used to evaluate the effect of cylindrical Al-Ag bimetallic NPs on the surface of a thin silicon absorber. At first, a unit cell with Al-Al paired nano-cylinders at the surface was evaluated and a photocurrent of 14.65 mA/cm² was obtained. In the case of a cell with paired Al-Ag bimetallic nano-cylinders, the photocurrent was increased to 16.15 mA/cm². This value was increased to 16.57 mA/cm² when paired polymetallic NPs were used. According to the results of this work, bimetallic and polymetallic nanoparticles can significantly improve the photocurrent of an ultra-thin silicon solar cell. The results of this work can be used to design better plasmonic-based light trapping systems for thin-film solar cells.

     

Evaluation of anticancer effects of cerium oxide nanoparticles on mouse fibrosarcoma cell line

Cerium oxide nanoparticles are associated with anticancer effects. While protecting normal cells, these nanoparticles exert their anticancer effects via oxidative stress and apoptosis in the cancer cells. In this study, the anticancer properties of nanoceria on fibrosarcoma cell line are evaluated. Cerium oxide nanoparticles were synthesized by the coprecipitation method and their anticancer effects on mouse fibrosarcoma tumor cells (WEHI164) were investigated. Viability assay was evaluated by MTT, and the DC-FDA assay performed for the detection of reactive oxygen species. For apoptosis assay, the annexin V/PI test was done as well as measuring the mRNA and protein expression levels of Bax and Bcl2 by real-time PCR and western blot method, respectively. Characterization of nanoceria reveals that synthesized nanoceria has cubic floruit structure with a size of about 30 nm. Toxicity assessment results show that nanoceria increases ROS levels and induced apoptosis in a dose-dependent manner in cancer cells (WEHI164), whereas low levels of toxicity were observed in normal cells (L929), even at the concentrations above 250 µg/ml in MTT assay. Real-time PCR and western blot assays showed that nanoceria could significantly increase the Bax expression in cancer cells. The results showed that nanoceria could act as a potential therapeutic agent for the treatment of fibrosarcoma.     

Exosomes as a novel cell-free therapeutic approach in gastrointestinal diseases

Cell communication through extracellular vesicles (EVs) has been defined for many years and it is not limited only to neighboring cells, but also distant ones in organisms receive these signals. These vesicles are secreted from the variety of cells and are composed of a distinctive component such as proteins, lipids, and nucleic acids. EVs have different classified subgroups regarding their cell origin, in this context, exosomes are the most appealing particles in cell biology, especially clinical in recent years and are represented as novel therapeutic agents with numerous advantages alongside and/or over cell therapy. However, cell therapy had a hopeful outcome in gastrointestinal diseases which have minimal alternatives in their treatments. Inflammatory bowel disease (IBD), liver fibrosis, gastrointestinal cancers are the examples that cell therapy and immunotherapy were applied in their treatment, therefore, the cell products like exosomes are the beneficial option in their treatment even cancers with promising results in animal models. In this review, we consider the main defined biogenesis, function, and component of secreted exosomes in different cells with a specific focus on the potential application of these exosomes as a cell-free therapeutic approach in gastrointestinal diseases like IBD, gastric cancer, and colon cancer. Additionally, exosomes role as therapeutic reagents mainly mesenchymal stem cells and dendritic cell-derived exosomes in different studies have been under intense investigation and even they are being studied in different clinical trials. Therefore, all these striking functions described for secretome implies the importance of these biocarriers.