https://pure.hw.ac.uk/ws/files/10766137/Melchels2010_Biomaterials_31_24_6121.pdf

A review on stereolithography and its applications in biomedical engineering

Activation of hepatic stellate cells (HSCs) in liver injury is the primary driver of hepatic fibrosis. In this Review, Tsuchida and Friedman detail the varied intracellular and extracellular signalling pathways leading to HSC activation, as well as the role of HSCs in liver fibrosis resolution and as therapeutic targets. Hepatic fibrosis is a dynamic process characterized by the net accumulation of extracellular matrix resulting from chronic liver injury of any aetiology, including viral infection, alcoholic liver disease and NASH. Activation of hepatic stellate cells (HSCs) — transdifferentiation of quiescent, vitamin-A-storing cells into proliferative, fibrogenic myofibroblasts — is now well established as a central driver of fibrosis in experimental and human liver injury. Yet, the continued discovery of novel pathways and mediators, including autophagy, endoplasmic reticulum stress, oxidative stress, retinol and cholesterol metabolism, epigenetics and receptor-mediated signals, reveals the complexity of HSC activation. Extracellular signals from resident and inflammatory cells including macrophages, hepatocytes, liver sinusoidal endothelial cells, natural killer cells, natural killer T cells, platelets and B cells further modulate HSC activation. Finally, pathways of HSC clearance have been greatly clarified, and include apoptosis, senescence and reversion to an inactivated state. Collectively, these findings reinforce the remarkable complexity and plasticity of HSC activation, and underscore the value of clarifying its regulation in hopes of advancing the development of novel diagnostics and therapies for liver disease.

Mechanisms of hepatic stellate cell activation

Nearing 30 years since its introduction, 3D printing technology is set to revolutionize research and teaching laboratories. This feature encompasses the history of 3D printing, reviews various printing methods, and presents current applications. The authors offer an appraisal of the future direction and impact this technology will have on laboratory settings as 3D printers become more accessible.

https://www.egr.msu.edu/eceshop/testingfacility/connex/papers/ac403397r.pdf

Evaluation of 3D printing and its potential impact on biotechnology and the chemical sciences.

3D Printing promises to produce complex biomedical devices according to computer design using patient-specific anatomical data. Since its initial use as pre-surgical visualization models and tooling molds, 3D Printing has slowly evolved to create one-of-a-kind devices, implants, scaffolds for tissue engineering, diagnostic platforms, and drug delivery systems. Fueled by the recent explosion in public interest and access to affordable printers, there is renewed interest to combine stem cells with custom 3D scaffolds for personalized regenerative medicine. Before 3D Printing can be used routinely for the regeneration of complex tissues (e.g. bone, cartilage, muscles, vessels, nerves in the craniomaxillofacial complex), and complex organs with intricate 3D microarchitecture (e.g. liver, lymphoid organs), several technological limitations must be addressed. In this review, the major materials and technology advances within the last five years for each of the common 3D Printing technologies (Three Dimensional Printing, Fused Deposition Modeling, Selective Laser Sintering, Stereolithography, and 3D Plotting/Direct-Write/Bioprinting) are described. Examples are highlighted to illustrate progress of each technology in tissue engineering, and key limitations are identified to motivate future research and advance this fascinating field of advanced manufacturing.

/pdf/recent-advances-in-3d-printing-of-biomaterials-2tjce7ks8k.pdf

Recent advances in 3D printing of biomaterials

2.1.6. Tacticity and Sequence: Advanced Control 4967 2.2. Transition Metal Catalysts 4967 2.2.1. Overviews of Catalysts 4967 2.2.2. Ruthenium 4967 2.2.3. Copper 4971 2.2.4. Iron 4971 2.2.5. Nickel 4975 2.2.6. Molybdenum 4975 2.2.7. Manganese 4976 2.2.8. Osmium 4976 2.2.9. Cobalt 4976 2.2.10. Other Metals 4976 2.3. Cocatalysts (Additives) 4977 2.3.1. Overview of Cocatalysts 4977 2.3.2. Reducing Agents 4977 2.3.3. Free Radical Initiators 4977 2.3.4. Metal Alkoxides 4977 2.3.5. Amines 4978 2.3.6. Halogen Source 4978 2.4. Initiators 4978 2.4.1. Overview of Initiators: Scope and Design 4978 2.4.2. Alkyl Halides 4978 2.4.3. Arenesulfonyl Halides 4979 2.4.4. N-Chloro Compounds 4979 2.4.5. Halogen-Free Initiators 4979 2.5. Solvents 4980 2.5.1. Overview of Solvents 4980 2.5.2. Catalyst Solubility and Coordination of Solvent 4981 2.5.3. Environmentally Friendly Solvents 4981 2.5.4. Water 4981 2.5.5. Catalytic Solvents: Catalyst Disproportionation 4981

Transition metal-catalyzed living radical polymerization : toward perfection in catalysis and precision polymer synthesis

Fabrication of 3D Biocompatible/Biodegradable Micro-Scaffolds Using Dynamic Mask Projection Microstereolithography

Hedgehog (Hh) signalling regulates hepatic fibrogenesis. MicroRNAs (miRNAs) mediate various cellular processes; however, their role in liver fibrosis is unclear. Here we investigate regulation of miRNAs in chronically damaged fibrotic liver. MiRNA profiling shows that expression of miR-378 family members (miR-378a-3p, miR-378b and miR-378d) declines in carbon tetrachloride (CCl4)-treated compared with corn-oil-treated mice. Overexpression of miR-378a-3p, directly targeting Gli3 in activated hepatic stellate cells (HSCs), reduces expression of Gli3 and profibrotic genes but induces gfap, the inactivation marker of HSCs, in CCl4-treated liver. Smo blocks transcriptional expression of miR-378a-3p by activating the p65 subunit of nuclear factor-κB (NF-κB). The hepatic level of miR-378a-3p is inversely correlated with the expression of Gli3 in tumour and non-tumour tissues in human hepatocellular carcinoma. Our results demonstrate that miR-378a-3p suppresses activation of HSCs by targeting Gli3 and its expression is regulated by Smo-dependent NF-κB signalling, suggesting miR-378a-3p has therapeutic potential for liver fibrosis.

/pdf/microrna-378-limits-activation-of-hepatic-stellate-cells-and-32f0fnn6h3.pdf

MicroRNA-378 limits activation of hepatic stellate cells and liver fibrosis by suppressing Gli3 expression

UV curable waterborne polyurethane/silica nanocomposites were designed and synthesized with functionalized silicas, where the functionalization was made with allyl isocyanate. The incorporated silica particles gave triple effects of multifunctional chemical cross-links, reinforcing fillers, and stress relaxation retarders. Consequently, functionalized silica incorporated into the polymer chains showed significantly improved mechanical and thermal properties than the simple addition of unmodified silica. Notably, over 99% shape fixity and shape recovery with minimum cyclic hysteresis were obtained for the repeated cycles at 1% loading of the modified silica. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Waterborne polyurethane nanocomposites having shape memory effects

An amino acid-modified and non-HEMA containing glass-ionomer cement

Graft copolymerization of acrylamidoglycolic acid (AGA) onto chitosan (CS) was carried out via a free radical initiation mechanism using a redox initiation system. Grafting ratio (%), efficiency, and conversion (%) were all found to depend on the content of potassium persulfate and AGA as well as on reaction temperature and time. Evidence of grafting was obtained by FTIR, 13 C NMR spectra, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. Hydroxyapatite (HA) polyelectrolyte complexes (PEC) were prepared by in situ addition of HA to the polymerization medium under optimal reaction conditions. Complexes were prepared using different ratios of HA with respect to CS-g-PAGA graft copolymers. The synthesized PECs were evaluated in swelling studies in phosphate-buffered saline. A mechanism for the free radical grafting and HA complexation were proposed.

Ildoo Chung

Papers

Fabrication of 3D Biocompatible/Biodegradable Micro-Scaffolds Using Dynamic Mask Projection Microstereolithography

MicroRNA-378 limits activation of hepatic stellate cells and liver fibrosis by suppressing Gli3 expression

Waterborne polyurethane nanocomposites having shape memory effects

An amino acid-modified and non-HEMA containing glass-ionomer cement

Synthesis and characterization of poly(acrylamidoglycolic acid) grafted onto chitosan and its polyelectrolyte complexes with hydroxyapatite