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topographical guidance

M D Sarker, Saman Naghieh, Adam D McInnes, David J Schreyer, Xiongbiao Chen
Nerve guidance conduits (NGCs) have been drawing considerable attention as an aid to promote regeneration of injured axons across damaged peripheral nerves. Ideally, NGCs should include physical and topographic axon guidance cues embedded as part of their composition. Over the past decades, much progress has been made in the development of NGCs that promote directional axonal regrowth so as to repair severed nerves. This paper briefly reviews the recent designs and fabrication techniques of NGCs for peripheral nerve regeneration...
February 3, 2018: Biotechnology Journal
Puneet Dang, Stephen A Fisher, Derek Stefanik, Junhyong Kim, Jonathan A Raper
Olfactory sensory neurons choose to express a single odorant receptor (OR) from a large gene repertoire and extend axons to reproducible, OR-specific locations within the olfactory bulb. This developmental process produces a topographically organized map of odorant experience in the brain. The axon guidance mechanisms that generate this pattern of connectivity, as well as those that coordinate OR choice and axonal guidance receptor expression, are incompletely understood. We applied the powerful approach of single-cell RNA-seq on newly born olfactory sensory neurons (OSNs) in young zebrafish larvae to address these issues...
January 31, 2018: PLoS Genetics
Paul A Wieringa, Ana Rita Gonçalves de Pinho, Silvestro Micera, Richard J A van Wezel, Lorenzo Moroni
Biofabrication techniques have endeavored to improve the regeneration of the peripheral nervous system (PNS), but nothing has surpassed the performance of current clinical practices. However, these current approaches have intrinsic limitations that compromise patient care. The "gold standard" autograft provides the best outcomes but requires suitable donor material, while implantable hollow nerve guide conduits (NGCs) can only repair small nerve defects. This review places emphasis on approaches that create structural cues within a hollow NGC lumen in order to match or exceed the regenerative performance of the autograft...
January 19, 2018: Advanced Healthcare Materials
Austen A Sitko, Takaaki Kuwajima, Carol Mason
Prior to forming and refining synaptic connections, axons of projection neurons navigate long distances to their targets. While much is known about guidance cues for axon navigation through intermediate choice points, whether and how axons are organized within tracts is less clear. Here we analyze the organization of retinal ganglion cell (RGC) axons in the developing mouse retinogeniculate pathway. RGC axons are organized by both eye-specificity and topography in the optic nerve and tract: ipsilateral RGC axons are segregated from contralateral axons and are offset laterally in the tract relative to contralateral axon topographic position...
January 11, 2018: Journal of Comparative Neurology
Liangliang Huang, Lei Zhu, Xiaowei Shi, Bing Xia, Zhongyang Liu, Shu Zhu, Yafeng Yang, Teng Ma, Pengzhen Cheng, Kai Luo, Jinghui Huang, Zhuojing Luo
Scaffolds with inner fillers that convey directional guidance cues represent promising candidates for nerve repair. However, incorrect positioning or non-uniform distribution of intraluminal fillers might result in regeneration failure. In addition, proper porosity (to enhance nutrient and oxygen exchange but prevent fibroblast infiltration) and mechanical properties (to ensure fixation and to protect regenerating axons from compression) of the outer sheath are also highly important for constructing advanced nerve scaffolds...
December 20, 2017: Acta Biomaterialia
Zhe Chen
Topographic arrangement of neuronal cell bodies and axonal tracts are crucial for proper wiring of the nervous system. This involves often-coordinated neuronal migration and axon guidance during development. Most neurons migrate from their birthplace to specific topographic coordinates as they adopt the final cell fates and extend axons. The axons follow temporospatial specific guidance cues to reach the appropriate targets. When neuronal or axonal migration or their coordination is disrupted, severe consequences including neurodevelopmental disorders and neurological diseases, can arise...
December 20, 2017: Seminars in Cell & Developmental Biology
Aune Koitmäe, Manuel Müller, Cornelius Sebastian Bausch, Jann Harberts, Wolfgang Hansen, Gabriele Loers, Robert H Blick
Here we present a designer's approach to building cellular neuronal networks based on a bio-compatible negative photo-resist with embedded coaxial feedthroughs made of semiconductor microtubes. The diameter of the microtubes is tailored and adjusted to the diemeter of the cerebellum axons having a diameter of 2-3 µm. The microtubes as well as the SU-8 layer serve as topographical cue to the axons. Apart from the topographical guidance we also employ chemical guidance cues enhancing neuron growth at designed spots...
December 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Ajay Tijore, Scott Alexander Irvine, Udi Sarig, Priyadarshini Mhaisalkar, Vrushali Baisane, Subbu S Venkatraman
Here, we have developed a 3D bioprinted microchanneled gelatin hydrogel that promotes human mesenchymal stem cell (hMSC) myocardial commitment and supports native cardiomyocytes (CMs) contractile functionality. Firstly, we studied the effect of bioprinted microchanneled hydrogel on the alignment, elongation, and differentiation of hMSC. Notably, the cells displayed well defined F-actin anisotropy and elongated morphology on the microchanneled hydrogel, hence showing the effects of topographical control over cell behavior...
December 13, 2017: Biofabrication
Kelly A Glendining, Sam C Liu, Marvin Nguyen, Nuwan Dharmaratne, Rajini Nagarajah, Miguel A Iglesias, Atomu Sawatari, Catherine A Leamey
BACKGROUND: The formation of visuotopically-aligned projections in the brain is required for the generation of functional binocular circuits. The mechanisms which underlie this process are unknown. Ten-m3 is expressed in a broad high-ventral to low-dorsal gradient across the retina and in topographically-corresponding gradients in primary visual centres. Deletion of Ten-m3 causes profound disruption of binocular visual alignment and function. Surprisingly, one of the most apparent neuroanatomical changes-dramatic mismapping of ipsilateral, but not contralateral, retinal axons along the representation of the nasotemporal retinal axis-does not correlate well with Ten-m3's expression pattern, raising questions regarding mechanism...
December 6, 2017: BMC Neuroscience
Kisuk Yang, Seung Jung Yu, Jong Seung Lee, Hak-Rae Lee, Gyeong-Eon Chang, Jungmok Seo, Taeyoon Lee, Eunji Cheong, Sung Gap Im, Seung-Woo Cho
Biophysical cues, such as topography, and electrical cues can provide external stimulation for the promotion of stem cell neurogenesis. Here, we demonstrate an electroconductive surface nanotopography for enhancing neuronal differentiation and the functional maturation of human neural stem cells (hNSCs). The electroconductive nanopatterned substrates were prepared by depositing a thin layer of titanium (Ti) with nanograting topographies (150 to 300 nm groove/ridge, the thickness of the groove - 150 μm) onto polymer surfaces...
December 7, 2017: Nanoscale
Dario Bonanomi
Motor neurons of the spinal cord are responsible for the assembly of neuromuscular connections indispensable for basic locomotion and skilled movements. A precise spatial relationship exists between the position of motor neuron cell bodies in the spinal cord and the course of their axonal projections to peripheral muscle targets. Motor neuron innervation of the vertebrate limb is a prime example of this topographic organization and by virtue of its accessibility and predictability has provided access to fundamental principles of motor system development and neuronal guidance...
November 14, 2017: Seminars in Cell & Developmental Biology
Ce Mo, Dongjun He, Fang Fang
Attention priority maps are topographic representations that are utilized for attention selection and guidance of task-related behavior during visual processing. Previous studies have identified attention priority maps of simple artificial stimuli in multiple cortical and subcortical areas, while investigating neural correlates of priority maps of natural stimuli is complicated by the complexity of their spatial structure and the difficulty of behaviorally characterizing their priority map. To overcome these challenges, we reconstructed the topographic representations of upright/invered face images from fMRI BOLD signals in human early visual areas V1-V3 based on a voxel-wise population receptive field model and behaviorally characterized the priority map as the first saccadic eye movement pattern when subjects performed a face matching task, relative to the condition in which subjects performed a phase-scrambled face matching task...
November 13, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Yulia Berkovitch, Talia Cohen, Eli Peled, Robert Schmidhammer, Hildner Florian, Andreas Teuschl, Susanne Wolbank, Dvir Yelin, Heinz Redl, Dror Seliktar
Treatment of peripheral nerve injuries has evolved over the past several decades to include the use of sophisticated new materials endowed with trophic and topographical cues that are essential for in vivo nerve fiber regeneration. In this research, we explored the use of an advanced design strategy for peripheral nerve repair, using biological and semi-synthetic hydrogels that enable controlled environmental stimuli to regenerate neurons and glial cells in a rat sciatic nerve resection model. The provisional nerve growth conduits were comprised of either natural fibrin, or adducts of synthetic polyethylene glycol (PEG) and fibrinogen or gelatin...
November 2, 2017: Journal of Tissue Engineering and Regenerative Medicine
Kristopher A Pruitt, Justin M Hill
PURPOSE: The purpose of this research is to determine the pacing and nutrition strategies which minimize completion time and carbohydrate intake for athletes competing in ultramarathon races. METHODS: We present the formulation of a two-phase optimization model. The first-phase mixed-integer nonlinear program (MINLP) determines the minimum completion time subject to the altitude, terrain, and distance of the race, as well as the mass and cardiovascular fitness of the athlete...
December 2017: European Journal of Applied Physiology
Audrey Chabrat, Guillaume Brisson, Hélène Doucet-Beaupré, Charleen Salesse, Marcos Schaan Profes, Axelle Dovonou, Cléophace Akitegetse, Julien Charest, Suzanne Lemstra, Daniel Côté, R Jeroen Pasterkamp, Monica I Abrudan, Emmanouil Metzakopian, Siew-Lan Ang, Martin Lévesque
Mesodiencephalic dopamine neurons play central roles in the regulation of a wide range of brain functions, including voluntary movement and behavioral processes. These functions are served by distinct subtypes of mesodiencephalic dopamine neurons located in the substantia nigra pars compacta and the ventral tegmental area, which form the nigrostriatal, mesolimbic, and mesocortical pathways. Until now, mechanisms involved in dopaminergic circuit formation remained largely unknown. Here, we show that Lmx1a, Lmx1b, and Otx2 transcription factors control subtype-specific mesodiencephalic dopamine neurons and their appropriate axon innervation...
October 16, 2017: Nature Communications
Xiaolong Lu, Fernando Soto, Jinxing Li, Tianlong Li, Yuyan Liang, Joseph Wang
Precise and reproducible manipulation of synthetic and biological microscale objects in complex environments is essential for many practical biochip and microfluidic applications. Here, we present an attractive acoustic topographical manipulation (ATM) method to achieve efficient and reproducible manipulation of diverse microscale objects. This new guidance method relies on the acoustically induced localized microstreaming forces generated around microstructures, which are capable of trapping nearby microobjects and manipulating them along a determined trajectory based on local topographic features...
November 8, 2017: ACS Applied Materials & Interfaces
Chiara Fedele, Maria De Gregorio, Paolo A Netti, Silvia Cavalli, Chiara Attanasio
Understanding cellular behavior in response to microenvironmental stimuli is central to tissue engineering. An increasing number of reports emphasize the high sensitivity of cells to the physical characteristics of the surrounding milieu and in particular, topographical cues. In this work, we investigated the influence of dynamic topographic signal presentation on sprout formation and the possibility to obtain a space-time control over sprouting directionality without growth factors, in order to investigate the contribution of just topography in the angiogenic process...
November 2017: Acta Biomaterialia
Braden L Leigh, Kristy Truong, Reid Bartholomew, Mark Ramirez, Marlan R Hansen, C Allan Guymon
Cochlear Implants (CIs) suffer from limited tonal resolution due, in large part, to spatial separation between stimulating electrode arrays and primary neural receptors. In this work, a combination of physical and chemical micropatterns, formed on acrylate polymers, are used to direct the growth of primary spiral ganglion neurons (SGNs), the inner ear neurons. Utilizing the inherent temporal and spatial control of photopolymerization, physical microgrooves are fabricated using a photomask in a single step process...
September 20, 2017: ACS Applied Materials & Interfaces
Alberto Bonisoli, Attilio Marino, Gianni Ciofani, Francesco Greco
The development of smart biointerfaces combining multiple functions is crucial for triggering a variety of cellular responses. In this work, wrinkled organic interfaces based on the conducting polymer poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonate) are developed with the aim to simultaneously convey electrical and topographical stimuli to cultured cells. The surface wrinkling of thin films on heat-shrink polymer sheets allows for rapid patterning of self-assembled anisotropic topographies characterized by micro/sub-microscale aligned wrinkles...
November 2017: Macromolecular Bioscience
Adina Badea, Joselle M McCracken, Emily G Tillmaand, Mikhail E Kandel, Aaron W Oraham, Molly B Mevis, Stanislav S Rubakhin, Gabriel Popescu, Jonathan V Sweedler, Ralph G Nuzzo
Understanding and controlling the interactions occurring between cells and engineered materials are central challenges toward progress in the development of biomedical devices. In this work, we describe materials for direct ink writing (DIW), an extrusion-based type of 3D printing, that embed a custom synthetic protein (RGD-PDL) within the microfilaments of 3D-hydrogel scaffolds to modify these interactions and differentially direct tissue-level organization of complex cell populations in vitro. The RGD-PDL is synthesized by modifying poly-d-lysine (PDL) to varying extents with peptides containing the integrin-binding motif Arg-Gly-Asp (RGD)...
September 13, 2017: ACS Applied Materials & Interfaces
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