Three-dimensional (3D) porous scaffolds combined with therapeutic stem cells play vital roles in tissue engineering. The adult brain has very limited regeneration ability after injuries such as trauma and stroke. In this study, injectable 3D silk fibroin-based hydrogel scaffolds with encapsulated neural stem cells were developed, aiming at supporting brain regeneration. To improve the function of the hydrogel towards neural stem cells, silk fibroin was modified by an IKVAV peptide through covalent binding. Both unmodified and modified silk fibroin hydrogels were obtained, through sonication, with mechanical stiffness comparable to that of brain tissue. Human neural stem cells were encapsulated in both hydrogels and the effects of IKVAV peptide conjugation on cell viability and neural differentiation were assessed. The silk fibroin hydrogel modified by IKVAV peptide showed increased cell viability and an enhanced neuronal differentiation capability, which contributed to understanding the effects of IKVAV peptide on the behaviour of neural stem cells. For these reasons, IKVAV-modified silk fibroin is a promising material for brain tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.

Novel nanocomposites based on type I collagen (Col) containing a small amount (17.4, 43.5, and 174 ppm) of gold nanoparticles (AuNPs, approximately 5 nm) were prepared in this study. The pure Col and Col-AuNP composites (Col-Au) were characterized by the UV-Vis spectroscopy (UV-Vis), surface-enhanced raman spectroscopy (SERS) and atomic force microscopy (AFM). The interaction between Col and AuNPs was confirmed by infrared (IR) spectra. The effect of AuNPs on the biocompatibility of Col, evaluated by the proliferation and reactive oxygen species (ROS) production of mesenchymal stem cells (MSCs) as well as the activation of monocytes and platelets, was investigated. Results showed that Col-Au had better biocompatibility than Col. Upon stimulation by vascular endothelial growth factor (VEGF) and stromal derived factor-1α (SDF-1α), MSCs expressed the highest levels of αvβ3 integrin/CXCR4, focal adhesion kinase (FAK), matrix metalloproteinase-2 (MMP-2), and Akt/endothelial nitric oxide synthase (eNOS) proteins when grown on the Col-Au (43.5 ppm) nanocomposite. Taken together, Col-Au nanocomposites may promote the proliferation and migration of MSCs and stimulate the endothelial cell differentiation. These results suggest that Col-Au may be used to construct tissue engineering scaffolds for vascular regeneration.

Different hydrogel materials have been prepared to investigate the effects of culture substrate on the behaviour of pluripotent cells. In particular, genipin-crosslinked gelatin-silk fibroin hydrogels of different compositions have been prepared, physically characterized and used as substrates for the culture of pluripotent cells. Pluripotent cells cultured on hydrogels remained viable and proliferated. Gelatin and silk fibroin promoted the proliferation of cells in the short and long term, respectively. Moreover, cells cultured on genipin-crosslinked gelatin-silk fibroin blended hydrogels were induced to an epithelial ectodermal differentiation fate, instead of the neural ectodermal fate obtained by culturing on tissue culture plates. This work confirms that specific culture substrates can be used to modulate the behaviour of pluripotent cells and that our genipin-crosslinked gelatin-silk fibroin blended hydrogels can induce pluripotent cells differentiation to an epithelial ectodermal fate. Copyright © 2014 John Wiley & Sons, Ltd.

Preoperative aspirin therapy is associated with a significant decrease in the risk of major cardiocerebral complications, renal failure, intensive care unit stay and 30-day mortality but does not increase the risk of readmissions in patients undergoing cardiac surgery.

A simple surface modification method, comprising of a thin coating with gold nanoparticles (AuNPs) and fibronectin (FN), was developed to improve the biocompatibility required for cardiovascular devices. The nanocomposites from FN and AuNPs (FN-Au) were characterized by the atomic force microscopy (AFM), UV-Vis spectrophotometry (UV-Vis), and Fourier transform infrared spectroscopy (FTIR). The biocompatibility of the nanocomposites was evaluated by the response of monocytes and platelets to the material surface in vitro. FN-Au coated surfaces demonstrated low monocyte activation and platelet activation. The behavior of human umbilical cord-derived mesenchymal stem cells (MSCs) on FN-Au was further investigated. MSCs on FN-Au nanocomposites particularly that containing 43.5 ppm of AuNPs (FN-Au 43.5 ppm) showed cell proliferation, low ROS generation, as well as increases in the protein expression levels of matrix metalloproteinase-9 (MMP-9) and endothelial nitric oxide synthase (eNOS), which may account for the enhanced MSC migration on the nanocomposites. These results suggest that the FN-Au nanocomposite thin film coating may serve as a potential and simple solution for the surface modification of blood-contacting devices such as vascular grafts.

Objectives Microglia are the main effectors in the inflammatory process of the central nervous system. Once overactivated, microglia may release proinflammatory cytokines (IL-1β, IL-6, TNF-α and IL-18, etc.) and accelerate neurodegeneration. Here, we aimed to explore the mechanism of how m6A methyltransferase METTL3 affects the inflammatory response of microglia, appropriately inhibiting the overactivation of microglia. Materials and methods Lipopolysaccharide (LPS)was used to construct a cellular inflammation model in vitro. To evaluate the expression of METTL3 and inflammatory cytokines (IL-1β, IL-6, TNF-α and IL-18) in cells, RT-PCR and ELISA were carried out. The related protein (TRAF6, NF-κB and I-κB) expression was examined adopting Western blot. Dot blot experiment was used to assess the effect of regulating METTL3 on the m6A level. Methylated RNA immunoprecipitation reaction was used to measure the effect of METTL3 on the m6A level of TRAF6 mRNA 3′-UTR. The co-immunoprecipitation experiment (IP) proved that METTL3 combines with TRAF6. ResultsIn LPS-mediated microglial inflammation, METTL3 expression was increased, and the expression of inflammatory cytokines (IL-1β, IL-6, TNF-α and IL-18) and inflammatory proteins (TRAF6 and NF-κB) were upregulated. METTL3 level was positively correlated with TRAF6, and the two proteins could bind to each other. Overexpression of METTL3 promoted the activation of the TRAF6-NF-κB pathway in an m6A-dependent manner, and inhibiting NF-κB attenuated METTL3-mediated microglial activation. Conclusion METTL3 promotes LPS-induced microglialinflammation by activating the TRAF6-NF-κB pathway.

Sufficient vascularization of the implant construct is required for tissue regeneration to ensure the supply of oxygen and nutrients. In our previous work, we established sonication-induced silk fibroin hydrogel to load neural stem cells for brain tissue engineering applications. In this study, we explored the application of silk fibroin as an injectable hydrogel for vascularization of soft tissues. We investigated the ability of outgrowth endothelial cells (OECs) in mono-culture or in co-culture with human bone marrow-derived mesenchymal stem cells (BM-MSCs) to form capillary networks in silk fibroin hydrogels. Furthermore, the silk fibroin hydrogel was modified with IKVAV peptide revealing a sequence derived from the extracellular matrix component laminin-1 to test its effects on angiogenesis, using unmodified and VVIAK modified silk fibroin hydrogel as controls. In monocultures of OECs, no angiogenic structures were observed in silk fibroin hydrogels. In contrast, vascular structures were abundant and increased in co-culture, as confirmed by immunocytochemistry and scanning electron microscopy (SEM) over 10 d of culture in silk fibroin-based hydrogels. Although no significant differences in angiogenic activity seem to be caused by the IKVAV peptide in our experimental settings, these results indicate that sonication-induced silk fibroin-based hydrogels support the formation of functional endothelial tubes and vascularization networks in the presence of mesenchymal cells supporting the vascular sprouting of endothelial cells.

Aim of review:Diabetes is a chronic and slowly progressing disease that has a tendency to develop rapidly deteriorating complications such as major adverse cardiovascular events (MACE), especially under the stress of surgery. While clinical strategy to prevent MACE is controversial and uncertain. Method: We conducted a comprehensive review of current clinical strategies in preventing perioperative MACE, in particularly related to diabetic patients. Results: The major findings are: 1) Current clinical studies have demonstrated that coronary artery bypass graft (CABG) is still a better therapy than percutaneous coronary intervention (PCI) on the ground of reducing repeat revascularization, myocardial infarction and death for most diabetic patients with left main-stem and multivessel coronary artery disease who require revascularization, however, it remains to be studied whether coronary revascularization before noncardiac surgery can protect diabetic patients from MACE; 2) There is lack of evidence that intensive or "tight" glycemic control perioperatively can reduce MACE, instead, a moderate or less stringent glucose management probably is safer for patients undergoing surgery;3) The recent results of clinical trials on beta-blockers appear to be disappointing in preventing MACE in surgical patients, including diabetic patients. Meanwhile, the perioperative therapy with statins, angiotensin-converting enzyme inhibitors or multifactorial interventions is promising in preventing MACE in diabetic patients. Summary: Further studies targeted at preventing MACE in diabetic patients undergoing surgery are needed in order to fight this major health problem in perioperative medicine. ABSTRACT