Modelling human neurodegeneration using induced pluripotent stem cells
Christine Hauskeller, Arne Manzeschke, Anja Pichl in The Matrix of Stem Cell Research, 2019
MND is a heterogeneous group of neurological disorders that causes rapidly progressive muscle weakness, affecting a person’s ability to walk, speak, swallow, and breathe (Worms, 2001). MND typically affects people in their mid-fifties. MND primarily attacks motor neurons, the neurons that control essential voluntary muscles of the body. Motor neurons consist of two types: the corticospinal motor neurons (or upper motor neurons) and the alpha motor neurons (or lower motor neurons). Motor neurons are responsible for the transmission of the movement commands from the motor cortex in the brain to the spinal cord (upper motor neurons), and from the spinal cord to the muscle fibres (lower motor neurons). The activation of muscle fibres by lower motor neurons leads to the contraction of the muscle, resulting in the voluntary movement of the body.
Management of Diabetic Gastroparesis
Emmanuel C. Opara, Sam Dagogo-Jack in Nutrition and Diabetes, 2019
In order to effectively restore function to the aganglionic gut, transplanted neural progenitor cells must not only migrate and survive, but also differentiate into neurons and become further specialized to release specific neurotransmitters. To restore motility, both excitatory motor neurons that promote smooth muscle cell contraction and inhibitory neurons to promote relaxation must be present. The ECM and smooth muscle cell–derived factors are critical mediators of enteric neural subset activation. The selective differentiation of neurons is stimulated by ECM proteins laminin, collagen I, and collagen IV in two-dimensional co-culture methods with ENPCs and SMCs [81]. Furthermore, the specific expression of excitatory neurons that express choline acetyltransferase (ChAT) and of inhibitory motor neurons that express neuronal nitric oxide synthase (nNOS) are stimulated by collagen I and collagen IV, respectively, in three-dimensional gels.
Potassium and calcium
Shaun Phillips in Fatigue in Sport and Exercise, 2015
Similarly, the firing rate of motor neurons decreases during sustained contractions, with this decrease closely matched to the slowing of fibre relaxation that occurs during muscle action.1 Therefore, the rate of stimulation is just enough to allow the muscle to produce the most force possible at any given time.33 Appropriately, this intelligent economy of resources is sometimes referred to as ‘muscle wisdom’.34 The delivery of action potentials also represents an economical approach to muscle activation. Action potentials often begin as groups of closely spaced potentials which allow a given force production with less fatigue,35 and a more effective force production for a given number of action potentials.1 Again, this minimises the number of action potentials required.
Extracellular vesicles isolated from human olfactory ensheathing cells enhance the viability of neural progenitor cells
Published in Neurological Research, 2020
Numerous studies have demonstrated that EVs or exosomes released from cells promote cell proliferation [53,54] and neurogenesis [55–57]. Most studies focused on exosomes derived from mesenchymal stem cells (MSCs) which are widely used cell types in transplantation therapy. However, generating MSCs is more costly than generating OECs. Thus, we aimed to develop a new platform for EV-based therapy from hOECs. We found that hOEC-derived EVs promote the proliferation of iPSC-NPCs in vitro, particularly after 72 h of incubation. Immunostaining of mature neuron markers such as islet-1 and MAP2 demonstrated that the proliferated NPCs exposed to OEC-EVs were mature and functional. Although the intensity of protein expression in one clone (iPSC-NPC1) did not clearly differ between control and EV-exposed cells, the number of cells was obviously increased. Additionally, we observed that immunostaining signal of iPSC-NPC2 showed higher intensity of HB9 expression. Homeobox HB9 is a protein encoded by human motor neuron and pancreas homeobox1. Traumatic SCI severely breaks down the neuronal circuit and motor function [58]. The motor neuron is important for the functional recovery of neuron disease or degeneration. Thus, we hypothesize that hOEC-EVs probably have positive effects on functional recovery in SCI. Our future efforts will focus on in vitro or in vivo studies to prove this hypothesis.
Blood perfusion changes during sacral nerve root stimulation versus surface gluteus electrical stimulation on in seated spinal cord injury
Published in Assistive Technology, 2019
Liang Qin Liu, Martin Ferguson-Pell
In theory, all muscles consist of a number of motor units, and the fibers belonging to a motor unit are dispersed and interlink among fibers of other units. A motor unit normally consists of one motor neuron and all of the muscle fibers it stimulates. The muscle fibers belonging to one motor unit can be spread throughout a part, or most of the entire muscle, depending on the number of fibers and size of the muscle. When a motor neuron is activated, all of the muscle fibers innervated by the motor neuron are stimulated and contracted. The activation of single motor neuron results in a weak distributed muscle contraction (twitch contraction). In contrast, the activation of more motor neurons will result in more muscle fibers being activated, and therefore, a stronger muscle contraction (tetanic contraction) was produced. The higher the recruitment of motor unit, the stronger the muscle contraction will be. The activation of more motor neurons will result in more muscle fibers being activated, and therefore, a stronger muscle contraction (Guyton & Hall, 0000). In comparison, between sacral nerve root stimulation versus traditional surface FES of gluteal muscles, the larger numbers of motor neurons recruitment in sacral nerve roots stimulation may produce stronger contraction than surface FES. Therefore, it can activate gluteus muscles more efficiently. Sacral nerve root stimulation can efficiently activate all motor neurons that innervate gluteal maximus, whereas surface FES of gluteus maximus may be limited by the size of electrodes and the depth of electrical signal to reach the muscle motor points.
Is it accurate to classify ALS as a neuromuscular disorder?
Published in Expert Review of Neurotherapeutics, 2020
Michael A. van Es, H. Stephan Goedee, Henk-Jan Westeneng, Tanja C.W. Nijboer, Leonard H. van den Berg
Patients gradually develop progressive motor deficits over the course of weeks or months, which can affect any voluntary muscle. This means that the initial presentation is very heterogeneous and ranges from dysarthria to a foot drop. Disease onset is usually focal, but with subsequent spreading to other regions of the body. Spread of the disease may be within the same region (from hand to upper arm) as well as between neuro-anatomically connected regions (rostro-caudal or contra-lateral)[12]. The degree of involvement of upper and lower motor neurons is also variable. Some patients predominantly show upper motor signs, with lower motor neuron involvement only becoming evident through neurophysiological studies or over the course of time. Similarly, there are patients with predominant lower motor neuron presentations[13]. Whether pure upper motor neuron (primary lateral sclerosis) and pure lower motor neuron syndromes (progressive spinal muscular atrophy) actually exist, should be seen as separate diseases or are restricted phenotypes of ALS remains a topic of debate [14–16].