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Mechanical engineering

María Puertas-Bartolomé, Lorena Benito-Garzón, Marta Olmeda-Lozano
Injectable hydrogels have demonstrated being a promising strategy for cartilage and bone tissue engineering applications, owing to their minimal invasive injection procedure, easy incorporation of cells and bioactive molecules, improved contact with the surrounding tissues and ability to match defects with complex irregular shapes, characteristics of osteoarthritic pathology. These unique properties make them highly suitable bioscaffolds for treating defects which are otherwise not easily accessible without and invasive surgical procedure...
2018: Advances in Experimental Medicine and Biology
Viviana P Ribeiro, Sandra Pina, J Miguel Oliveira, Rui L Reis
Osteochondral lesions treatment and regeneration demands biomimetic strategies aiming physicochemical and biological properties of both bone and cartilage tissues, with long-term clinical outcomes. Hydrogels and scaffolds appeared as assertive approaches to guide the development and structure of the new osteochondral engineered tissue. Moreover, these structures alone or in combination with cells and bioactive molecules bring the mechanical support after in vitro and in vivo implantation. Moreover, multilayered structures designed with continuous interfaces furnish appropriate features of the cartilage and subchondral regions, namely microstructure, composition, and mechanical properties...
2018: Advances in Experimental Medicine and Biology
Marta R Casanova, Rui L Reis, Albino Martins, Nuno M Neves
Electrospinning, an electrostatic fiber fabrication technique, has attracted significant interest in recent years due to its versatility and ability to produce highly tunable nanofibrous meshes. These nanofibrous meshes have been investigated as promising tissue engineering scaffolds since they mimic the scale and morphology of the native extracellular matrix. The sub-micron diameter of fibers produced by this process presents various advantages like the high surface area to volume ratio, tunable porosity, and the ability to manipulate the nanofiber composition in order to get desired properties and functionality...
2018: Advances in Experimental Medicine and Biology
Ana Mora-Boza, María Luisa Lopez-Donaire
Over the recent years, the advent of 3D bioprinting technology has marked a milestone in osteochondral tissue engineering (TE) research. Nowadays, the traditional used techniques for osteochondral regeneration remain to be inefficient since they cannot mimic the complexity of joint anatomy and tissue heterogeneity of articular cartilage. These limitations seem to be solved with the use of 3D bioprinting which can reproduce the anisotropic extracellular matrix (ECM) and heterogeneity of this tissue. In this chapter, we present the most commonly used 3D bioprinting approaches and then discuss the main criteria that biomaterials must meet to be used as suitable bioinks, in terms of mechanical and biological properties...
2018: Advances in Experimental Medicine and Biology
Ivana Gadjanski
In order to engineer biomimetic osteochondral (OC) construct, it is necessary to address both the cartilage and bone phase of the construct, as well as the interface between them, in effect mimicking the developmental processes when generating hierarchical scaffolds that show gradual changes of physical and mechanical properties, ideally complemented with the biochemical gradients. There are several components whose characteristics need to be taken into account in such biomimetic approach, including cells, scaffolds, bioreactors as well as various developmental processes such as mesenchymal condensation and vascularization, that need to be stimulated through the use of growth factors, mechanical stimulation, purinergic signaling, low oxygen conditioning, and immunomodulation...
2018: Advances in Experimental Medicine and Biology
Zaida Ortega, María Elena Alemán, Ricardo Donate
The use of fibers into scaffolds is a way to mimic natural tissues, in which fibrils are embedded in a matrix. The use of fibers can improve the mechanical properties of the scaffolds and may act as structural support for cell growth. Also, as the morphology of fibrous scaffolds is similar to the natural extracellular matrix, cells cultured on these scaffolds tend to maintain their phenotypic shape. Different materials and techniques can be used to produce micrfibers- and nanofibers for scaffolds manufacturing; cells, in general, adhere and proliferate very well on PCL, chitosan, silk fibroin, and other nanofibers...
2018: Advances in Experimental Medicine and Biology
Ohan S Manoukian, Connor Dieck, Taylor Milne, Caroline N Dealy, Swetha Rudraiah, Sangamesh G Kumbar
For many years, the avascular nature of cartilage tissue has posed a clinical challenge for replacement, repair, and reconstruction of damaged cartilage within the human body. Injuries to cartilage and osteochondral tissues can be due to osteoarthritis, sports, aggressive cancers, and repetitive stresses and inflammation on wearing tissue. Due to its limited capacity for regeneration or repair, there is a need for suitable material systems which can recapitulate the function of the native osteochondral tissue physically, mechanically, histologically, and biologically...
2018: Advances in Experimental Medicine and Biology
Sandra Pina, Rita Rebelo, Vitor Manuel Correlo, J Miguel Oliveira, Rui L Reis
Considerable advances in tissue engineering and regeneration have been accomplished over the last decade. Bioceramics have been developed to repair, reconstruct, and substitute diseased parts of the body and to promote tissue healing as an alternative to metallic implants. Applications embrace hip, knee, and ligament repair and replacement, maxillofacial reconstruction and augmentation, spinal fusion, bone filler, and repair of periodontal diseases. Bioceramics are well-known for their superior wear resistance, high stiffness, resistance to oxidation, and low coefficient of friction...
2018: Advances in Experimental Medicine and Biology
Zhen Yan, Prachi Joshi, Christopher A Gorski, James G Ferry
Consumption of methane by aerobic and anaerobic microbes governs the atmospheric level of this powerful greenhouse gas. Whereas a biochemical understanding of aerobic methanotrophy is well developed, a mechanistic understanding of anaerobic methanotrophy has been prevented by the unavailability of pure cultures. Here we report a biochemical investigation of Methanosarcina acetivorans, a methane-producing species capable of anaerobic methanotrophic growth dependent on reduction of Fe(III). Our findings support a pathway anchored by Fe(III)-dependent mechanisms for energy conservation driving endergonic reactions that are key to methanotrophic growth...
April 24, 2018: Nature Communications
Shu-Wei Wu, Xifeng Liu, A Lee Miller, Yu-Shiuan Cheng, Ming-Long Yeh, Lichun Lu
In the present study, we fabricated non-toxic, injectable, and thermo-sensitive NIPAAm-g-chitosan (NC) hydrogels with thiol modification for introduction of disulfide cross-linking strategy. Previously, NIPAAm and chitosan copolymer has been proven to have excellent biocompatibility, biodegradability and rapid phase transition after injection, suitable to serve as cell carriers or implanted scaffolds. However, weak mechanical properties significantly limit their potential for biomedical fields. In order to overcome this issue, we incorporated thiol side chains into chitosan by covalently conjugating N-acetyl-cysteine (NAC) with carbodiimide chemistry to strengthen mechanical properties...
July 15, 2018: Carbohydrate Polymers
Meng Yuan, Bo Bi, Jiachang Huang, Renxi Zhuo, Xulin Jiang
In situ forming injectable hydrogels based on thermosensitive polymers are being investigated for tissue engineering applications. However, the major limitations of this kind of hydrogels are low gel stability and weak mechanical properties under physiological conditions. Here, thermosensitive hydroxypropyl chitin (HPCH) was synthesized homogenously and subsequently functionalized with photocrosslinkable methacrylate groups via glycidyl methacrylate to generate glycidyl methacrylate-modified HPCH (GM-HPCH)...
July 15, 2018: Carbohydrate Polymers
Pradeep Lal, Hideyuki Tanabe, Maximiliano L Suster, Deepak Ailani, Yuri Kotani, Akira Muto, Mari Itoh, Miki Iwasaki, Hironori Wada, Emre Yaksi, Koichi Kawakami
BACKGROUND: Fear conditioning is a form of learning essential for animal survival and used as a behavioral paradigm to study the mechanisms of learning and memory. In mammals, the amygdala plays a crucial role in fear conditioning. In teleost, the medial zone of the dorsal telencephalon (Dm) has been postulated to be a homolog of the mammalian amygdala by anatomical and ablation studies, showing a role in conditioned avoidance response. However, the neuronal populations required for a conditioned avoidance response via the Dm have not been functionally or genetically defined...
April 25, 2018: BMC Biology
Hanis Nazihah Hasmad, Mohd Reusmaazran Yusof, Zainul Rashid Mohd Razi, Ruszymah Binti Haji Idrus, Shiplu Roy Chowdhury
Fabrication of composite scaffolds is one of the strategies proposed to enhance the functionality of tissue engineered scaffolds for improved tissue regeneration. By combining multiple elements together, unique biomimetic scaffolds with desirable physical and mechanical properties can be tailored for tissue-specific applications. Despite having a highly porous structure, the utility of electrospun fibers (EF) as scaffold is usually hampered by their insufficient mechanical strength. In this study, we attempted to produce a mechanically competent scaffold with cell-guiding ability by fabricating aligned PLGA fibers on decellularized human amniotic membrane (HAM), known to possess favorable tensile and wound healing properties...
April 25, 2018: Tissue Engineering. Part C, Methods
S J Sun, J H Huo, Z J Geng, X Y Sun, X B Fu
Gene engineering has attracted worldwide attention because of its ability of precise location of disease mutations in genome. As a new gene editing technology, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) system is simple, fast, and accurate to operate at a specific gene site. It overcomes the long-standing problem of conventional operation. At the same time, stem cells are a good foundation for establishing disease model in vitro. Therefore, it has great significance to combine stem cells with the rapidly developing gene manipulation techniques...
April 20, 2018: Zhonghua Shao Shang za Zhi, Zhonghua Shaoshang Zazhi, Chinese Journal of Burns
Taisuke Masuda, Mitsuhiro Ukiki, Yuka Yamagishi, Michiya Matsusaki, Mitsuru Akashi, Utako Yokoyama, Fumihito Arai
Although there is a great need for suitable vascular replacements in clinical practice, much progress needs to be made toward the development of a fully functional tissue-engineered construct. We propose a fabrication method of engineered tubular tissue for small blood vessels via a layer-by-layer cellular assembly technique using mouse smooth muscle cells, the construction of a poly-(L-lactide-co-ε-caprolactone) (PLCL) scaffold, and integration in a microfluidic perfusion culture system. The cylindrical PLCL scaffold is incised, expanded, and its surface is laminated with the cell layers...
April 21, 2018: Journal of Biotechnology
Joel Corbin, Amewu Antoinette Mensah, Simone Maria Pieber, Jürgen Orasche, Bernhard Michalke, Marco Zanatta, Hendryk Czech, Dario Massabò, Francesco Buatier de Mongeot, Carlo Mennucci, Imad El Haddad, Nivedita K Kumar, Benjamin Stengel, Yuting Huang, Ralf Zimmermann, Andre S H Prevot, Martin Gysel
Heavy fuel oil (HFO) particulate matter (PM) emitted by marine engines is known to contain toxic heavy metals including vanadium (V) and nickel (Ni). The toxicity of such metals will depend on the their chemical state, size distribution, and mixing state. Using online soot-particle aerosol mass spectrometry (SP-AMS), we quantified the mass of five metals (V, Ni, Fe, Na, and Ba) in HFO-PM soot particles produced by a marine diesel research engine. The in-soot metal concentrations were compared to 25 in-PM 2...
April 24, 2018: Environmental Science & Technology
Shifeng Yan, Pengfei Xia, Shenghua Xu, Kunxi Zhang, Guifei Li, Lei Cui, Jingbo Yin
Porous microcarriers have aroused increasing attention recently, which can create a protected environment for sufficient cell seeding density, facilitate oxygen and nutrient transfer, and well support the cell attachment and growth. In this study, porous microcarriers fabricated from the strontium-substituted hydroxyapatite-graft-poly(γ-benzyl-L-glutamate) (Sr10-HA-g-PBLG) hybrid nanocomposite were developed. The surface grating of PBLG, the micromorphology and element distribution, mechanical strength, in vitro degradation and Sr2+ ion release of the obtained Sr10-HA-g-PBLG porous microcarriers were investigated, respectively...
April 24, 2018: ACS Applied Materials & Interfaces
Honglai Li, Hongjun Liu, Linwei Zhou, Xueping Wu, Yuhao Pan, Wei Ji, Biyuan Zheng, Qinglin Zhang, Xiujuan Zhuang, Xiaoli Zhu, Xiao Wang, Xiangfeng Duan, Anlian Pan
Atomic substitution offers an important route to achieve composition engineered two-dimensional nanostructures and their heterostructures. Despite the recent research progress, the fundamental understanding of the reaction mechanism has still remained unclear. Here we reveal the atomic substitution mechanism of two dimensional atomic layered materials. We found that the atomic substitution process is depending on the varying lattice constant (strain) in monolayer crystals, dominated by two strain-tuning (self-promoted and self-limited) mechanisms using density functional theory calculations...
April 24, 2018: ACS Nano
Clotilde Castaldo, Isotta Chimenti
Components of the cardiac extracellular matrix (ECM) are synthesized by residing cells and are continuously remodeled by them. Conversely, residing cells (including primitive cells) receive constant biochemical and mechanical signals from the ECM that modulate their biology. The pathological progression of heart failure affects all residing cells, inevitably causing profound changes in ECM composition and architecture that, in turn, impact on cell phenotypes. Any regenerative medicine approach must aim at sustaining microenvironment conditions that favor cardiogenic commitment of therapeutic cells and minimize pro-fibrotic signals, while conversely boosting the capacity of therapeutic cells to counteract adverse remodeling of the ECM...
April 24, 2018: Stem Cells Translational Medicine
G I Popov, P V Popriadukhin, I P Dobrovol'skaia, V E Iudin, V N Vavilov, G Iu Iukina, E M Ivan'kova
In order to create a tissue-engineered vascular graft we elaborated a matrix consisting of nanofibres of biodegradable polymer L-polylactide. We worked out the methodology of crystallization of the matrix on a rod, making it possible to manufacture specimens possessing strength and deformity characteristics superior to those of native vessels. This was followed by a series of chronic experiments on implanting the elaborated matrix into the abdominal aorta of rats for the duration of up to 16 months. We obtained satisfactory parameters of the patency of the matrices (71%)...
2018: Angiologii︠a︡ i Sosudistai︠a︡ Khirurgii︠a︡, Angiology and Vascular Surgery
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