A micromechanical procedure for viscoelastic characterization of the axons and ECM of the brainstem

Javid, Samad; Rezaei, Asghar; Karami, G.

doi:10.1016/j.jmbbm.2013.11.010

Cited by 57 publications

(48 citation statements)

References 26 publications

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“…This behaviour is consistent with the picture of the brain as largely a dense colloidal system (in which the cell bodies are the colloids) connected by an adhesive mesh of ECM, direct cell-cell contacts and connections via cell processes (for example, dendrite, axon and glial processes). The overall CNS stiffness is comparable to that of individual cells and, for example, in the brainstem, axons have been shown to be stiffer than the surrounding ECM 47 . Further, as previously mentioned, collagen is absent from the ECM of the brain, which only takes about 20% of the volume and thus is unlikely to have a large load-bearing role.…”

Section: Tissue Considerationsmentioning

confidence: 93%

“…By contrast, MRE shows fluidization with age (and that female brains are more elastic than male brains) 65 . Such discrepancies are not uncommon in this field and are widely discussed 22,47,51,65,66 . They could emanate from different preparative procedures of the tissue, time and length scales, as well as modes of deformation, and the change of properties between in vivo and in vitro measurements, among other possible factors.…”

Section: Tissue Considerationsmentioning

confidence: 97%

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Materials and technologies for soft implantable neuroprostheses

2016

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| Implantable neuroprostheses are engineered systems designed to restore or substitute function for individuals with neurological deficits or disabilities. These systems involve at least one uni-or bidirectional interface between a living neural tissue and a synthetic structure, through which information in the form of electrons, ions or photons flows. Despite a few notable exceptions, the clinical dissemination of implantable neuroprostheses remains limited, because many implants display inconsistent long-term stability and performance, and are ultimately rejected by the body. Intensive research is currently being conducted to untangle the complex interplay of failure mechanisms. In this Review, we emphasize the importance of minimizing the physical and mechanical mismatch between neural tissues and implantable interfaces. We explore possible materials solutions to design and manufacture neurointegrated prostheses, and outline their immense therapeutic potential. NATURE REVIEWS | MATERIALSADVANCE ONLINE PUBLICATION | 1 REVIEWS© 2 0 1 6 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e . A l l r i g h t s r e s e r v e d .

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Section: Tissue Considerationsmentioning

confidence: 93%

Section: Tissue Considerationsmentioning

confidence: 97%

Materials and technologies for soft implantable neuroprostheses

2016

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“…Supra-threshold dynamic strain accompanying the spectrum of TBI can profoundly influence cell behavior and function without causing gross tissue destruction. For example, although axons are capable of sustaining minor membrane deformations, they are rigid structures within an elastic extracellular surround (Javid et al, 2014) and deleterious mechanical stress experienced at the onset of TBI-induced damage produces immediate plasmalemmal instability and cytoskeletal disassembly (Povlishock, 1993; Pettus and Povlishock, 1996; Singleton and Povlishock, 2004). Astrocytes appear equally susceptible to membrane distortions and poration (Cullen et al, 2011).…”

Section: Tbi Mechanopathogenesis As a Trigger Of Astrocyte Reactivitymentioning

confidence: 99%

Astrocyte roles in traumatic brain injury

Burda

Bernstein

Sofroniew

2016

Experimental Neurology

606

479

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Astrocytes sense changes in neural activity and extracellular space composition. In response, they exert homeostatic mechanisms critical for maintaining neural circuit function, such as buffering neurotransmitters, modulating extracellular osmolarity and calibrating neurovascular coupling. In addition to upholding normal brain activities, astrocytes respond to diverse forms of brain injury with heterogeneous and progressive changes of gene expression, morphology, proliferative capacity and function that are collectively referred to as reactive astrogliosis. Traumatic brain injury (TBI) sets in motion complex events in which noxious mechanical forces cause tissue damage and disrupt central nervous system (CNS) homeostasis, which in turn trigger diverse multi-cellular responses that evolve over time and can lead either to neural repair or secondary cellular injury. In response to TBI, astrocytes in different cellular microenvironments tune their reactivity to varying degrees of axonal injury, vascular disruption, ischemia and inflammation. Here we review different forms of TBI-induced astrocyte reactivity and the functional consequences of these responses for TBI pathobiology. Evidence regarding astrocyte contribution to post-traumatic tissue repair and synaptic remodeling is examined, and the potential for targeting specific aspects of astrogliosis to ameliorate TBI sequelae is considered.

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“…Combining the equations above, we determined that and consequently k mt = k sp Δ d max = 0.3 E L πR 2 . A reasonable value for the axon's longitudinal Young's modulus is E L ≃ 10 kPa [43], resulting in , at T = 300° K .…”

Section: Materials and Modelsmentioning

confidence: 99%

Modeling of the axon membrane skeleton structure and implications for its mechanical properties

Zhang

Abiraman

et al. 2017

PLoS Comput Biol

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Super-resolution microscopy recently revealed that, unlike the soma and dendrites, the axon membrane skeleton is structured as a series of actin rings connected by spectrin filaments that are held under tension. Currently, the structure-function relationship of the axonal structure is unclear. Here, we used atomic force microscopy (AFM) to show that the stiffness of the axon plasma membrane is significantly higher than the stiffnesses of dendrites and somata. To examine whether the structure of the axon plasma membrane determines its overall stiffness, we introduced a coarse-grain molecular dynamics model of the axon membrane skeleton that reproduces the structure identified by super-resolution microscopy. Our proposed computational model accurately simulates the median value of the Young’s modulus of the axon plasma membrane determined by atomic force microscopy. It also predicts that because the spectrin filaments are under entropic tension, the thermal random motion of the voltage-gated sodium channels (Nav), which are bound to ankyrin particles, a critical axonal protein, is reduced compared to the thermal motion when spectrin filaments are held at equilibrium. Lastly, our model predicts that because spectrin filaments are under tension, any axonal injuries that lacerate spectrin filaments will likely lead to a permanent disruption of the membrane skeleton due to the inability of spectrin filaments to spontaneously form their initial under-tension configuration.

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A micromechanical procedure for viscoelastic characterization of the axons and ECM of the brainstem

Cited by 57 publications

References 26 publications

Materials and technologies for soft implantable neuroprostheses

Materials and technologies for soft implantable neuroprostheses

Astrocyte roles in traumatic brain injury

Modeling of the axon membrane skeleton structure and implications for its mechanical properties

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