Motor neuron apoptosis and neuromuscular junction perturbation are prominent features in a Drosophila model of Fus-mediated ALS

AbstractInvestigations of the human neuromuscular junction (NMJ) have predominately utilised experimental animals, model organisms, or monolayer cell cultures that fail to represent the physiological complexity of the synapse. Consequently, there remains a paucity of data regarding the development of the human NMJ and a lack of systems that enable investigation of the motor unit. This work addresses this need, providing the methodologies to bioengineer 3D models of the human motor unit. Spheroid culture of iPSC derived motor neuron progenitors augmented the transcription of OLIG2, ISLET1 and SMI32 motor neuron mRNAs ~ 400, ~ 150 and ~ 200-fold respectively compared to monolayer equivalents. Axon projections of adhered spheroids exceeded 1000 μm in monolayer, with transcription of SMI32 and VACHT mRNAs further enhanced by addition to 3D extracellular matrices in a type I collagen concentration dependent manner. Bioengineered skeletal muscles produced functional tetanic and twitch profiles, demonstrated increased acetylcholine receptor (AChR) clustering and transcription of MUSK and LRP4 mRNAs, indicating enhanced organisation of the post-synaptic membrane. The number of motor neuron spheroids, or motor pool, required to functionally innervate 3D muscle tissues was then determined, generating functional human NMJs that evidence pre- and post-synaptic membrane and motor nerve axon co-localisation. Spontaneous firing was significantly elevated in 3D motor units, confirmed to be driven by the motor nerve via antagonistic inhibition of the AChR. Functional analysis outlined decreased time to peak twitch and half relaxation times, indicating enhanced physiology of excitation contraction coupling in innervated motor units. Our findings provide the methods to maximise the maturity of both iPSC motor neurons and primary human skeletal muscle, utilising cell type specific extracellular matrices and developmental timelines to bioengineer the human motor unit for the study of neuromuscular junction physiology.

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A three-dimensional culture model of innervated human skeletal muscle enables studies of the adult neuromuscular junction and disease modeling

10.1101/275545 ◽

2018 ◽

Cited By ~ 1

Author(s):

Mohsen Afshar Bakooshli ◽

Ethan S Lippmann ◽

Ben Mulcahy ◽

Nisha R Iyer ◽

Christine T Nguyen ◽

...

Keyword(s):

Skeletal Muscle ◽

Neuromuscular Junction ◽

Motor Neuron ◽

Motor Neurons ◽

Human Skeletal Muscle ◽

Disease Modeling ◽

De Novo ◽

Muscle Fibers ◽

Three Dimensional ◽

Adult Human

SummaryTwo-dimensional (2D) human skeletal muscle fiber cultures are ill equipped to support the contractile properties of maturing muscle fibers. This limits their application to the study of adult human neuromuscular junction (NMJ) development, a process requiring maturation of muscle fibers in the presence of motor neuron endplates. Here we describe a three-dimensional (3D) co-culture method whereby human muscle progenitors mixed with human pluripotent stem cell-derived motor neurons self-organize to form functional NMJ connections within two weeks. Functional connectivity between motor neuron endplates and muscle fibers is confirmed with calcium transient imaging and electrophysiological recordings. Notably, we only observed epsilon acetylcholine receptor subunit protein upregulation and activity in 3D co-culture. This demonstrates that the 3D co-culture system supports a developmental shift from the embryonic to adult form of the receptor that does not occur in 2D co-culture. Further, 3D co-culture treatments with myasthenia gravis patient sera shows the ease of studying human disease with the system. This work delivers a simple, reproducible, and adaptable method to model and evaluate adult human NMJ de novo development and disease in culture.

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The Function of Neuromuscular Junction in Upper Motor Neuron Weakness

Neuroprosthetics: from Basic Research to Clinical Applications ◽

10.1007/978-3-642-80211-9_16 ◽

1996 ◽

pp. 129-135

Author(s):

J. V. Trontelj ◽

J. M. Fernandez ◽

M. Mihelin ◽

D. Rugelj

Keyword(s):

Neuromuscular Junction ◽

Motor Neuron

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Weakness

Mayo Clinic Essential Neurology ◽

10.1093/med/9780190206895.003.0007 ◽

2018 ◽

pp. 207-238

Author(s):

Andrea C. Adams

Keyword(s):

Nervous System ◽

Neuromuscular Junction ◽

Motor Neuron ◽

Motor System ◽

Lower Motor Neuron ◽

Diagnostic Challenge ◽

Common Complaint ◽

Motor Nerves

Weakness is a common complaint. Most patients use the term weakness to imply fatigue, general illness, or myalgias. Determining whether a patient has actual neuromuscular weakness can be a diagnostic challenge. Disease of the motor system can occur at all levels of the nervous system. This chapter considers disorders of the lower motor neuron, including disorders of muscle (myopathies), the neuromuscular junction, and motor nerves.

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Erythropoietin prevents motor neuron apoptosis and neurologic disability in experimental spinal cord ischemic injury

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.042693799 ◽

2002 ◽

Vol 99 (4) ◽

pp. 2258-2263 ◽

Cited By ~ 340

Author(s):

M. Celik ◽

N. Gokmen ◽

S. Erbayraktar ◽

M. Akhisaroglu ◽

S. Konakc ◽

...

Keyword(s):

Spinal Cord ◽

Motor Neuron ◽

Ischemic Injury ◽

Neurologic Disability ◽

Neuron Apoptosis

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Dropped head syndrome due to neuromuscular disease: clinical manifestation and evaluation

Neurology International ◽

10.4081/ni.2019.8198 ◽

2019 ◽

Vol 11 (2) ◽

Cited By ~ 2

Author(s):

Ahmet Burakgazi ◽

Perry Richardson ◽

Mohammad Abu-Rub

Keyword(s):

Neuromuscular Junction ◽

Peripheral Nerve ◽

Motor Neuron ◽

Clinical Manifestation ◽

Neuromuscular Disease ◽

Clinical Approach ◽

Immunomodulating Therapy ◽

Dropped Head Syndrome

In this article, we discuss the clinical approach to patients with dropped head syndrome and identify the various neuromuscular causes of dropped head syndrome, including muscle, neuromuscular junction, peripheral nerve, and motor neuron etiologies. We aim to increase awareness and recognition of the entity of dropped head syndrome and factors that may predict responses to immunomodulating therapy.

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