Biology subjects

Ashton, R. S.

Publications and source records attributed to Ashton, R. S..

5 recordsLinked to original sources

bioRxiv2025

Human microphysiological model of dorsal root ganglion-spinal cord dorsal horn circuitry recapitulates opioid induced effects

Microphysiological systems (MPSs) are engineered, in vitro platforms which have been established as viable alternatives to animal models for pre-clinical research with unique advantages over conventional model systems. Many MPSs utilize 3-dimensional (3D) tissue constructs that enable biomimetic cell-cell interactions, allow for extended culture periods, and provide the time necessary for the emergence of physical and physiological characteristics of more mature tissues. Here, we present a novel MPS using human induced pluripotent stem cell (hiPSC)-derived spinal cord dorsal horn (SCDH) spheroids co-cultured with hiPSC-derived dorsal root ganglion (DRG) sensory spheroids in a microengineered hydrogel system to create a "connectoid" model of afferent pain circuitry. SCDH spheroids were functionally innervated by peripheral sensory neurons, and prolonged maturation of hiPSC-derived SCDH neurons within the connectoid system enabled derivation of crucial late-born cell types unattainable using 2D differentiations. Furthermore, hiPSC-derived SCDH spheroids spontaneously generate rhythmic, complex, synaptically-driven electrophysiological waveforms that are disinhibited by morphine exposure, consistent with spinal mechanisms of opioid-induced pruritus and hypersensitivity. One Sentence SummaryhiPSC-derived afferent sensory circuitry model, with NK1R+ spinal cord dorsal horn neurons, yields electrophysiologically mimetic response to opioids.

bioengineering↗

bioRxiv2024

RosetteArray Platform for Quantitative High-Throughput Screening of Human Neurodevelopmental Risk

Neural organoids have revolutionized how human neurodevelopmental disorders (NDDs) are studied. Yet, their utility for screening chemical hazards and prospective therapeutics for NDDs is limited by a lack of morphological reproducibility and cost-effective scalability. Here, we describe the RosetteArray platform, which can be used as an off-the-shelf, 96-well plate assay that standardizes incipient forebrain and spinal cord organoid morphogenesis as adherent, micropatterned, 3-D, singularly polarized neural rosette tissues ([~]200 and [~]800 per well, respectively). Seeded directly from cryopreserved human pluripotent stem cells, RosetteArrays are cultured over 6-8 days and fixed, immunostained and imaged in situ to enable artificial intelligence-based quantitative analysis. By screening the inception of [~]75,000 neural organoids throughout this manuscript, we provide proof-of-concept demonstrations of the platforms utility for detecting developmental neurotoxicity hazard and screening genetic and environmental factors known to cause clinical Neural Tube Defect risk. Given the documented perturbation of rosette morphogenesis in neural organoid models of several NDDs, the RosetteArray platform could enable quantitative high-throughput screening (qHTS) of human neurodevelopmental risk across regulatory and precision medicine applications.

neuroscience↗

bioRxiv2022

The autism-associated gene SYNGAP1 regulates human cortical neurogenesis

Autism spectrum disorder (ASD) is a genetically heterogeneous disorder linked with rare, inherited and de novo mutations occurring in two main functional gene categories: gene expression regulation and synaptic function1. Accumulating evidence points to dysregulation in cortical neurogenesis as a convergent mechanism in ASD pathophysiology2-8. While asynchronous development has been identified as a shared feature among ASD-risk genes in the category of gene expression regulation, it remains unknown whether this phenotype is also associated with ASD-risk genes in the synaptic function category. Here we show for the first time the expression of the synaptic Ras GTP-ase activating protein 1 (SYNGAP1), one of the top ASD risk genes9, in human cortical progenitors (hCPs). Interestingly, we found that multiple components of the postsynaptic density (PSD) of excitatory synapses, of which SYNGAP1 is one of the most abundant components 10,11, are enriched in the proteome of hCPs. Specifically, we discover that SYNGAP1 is expressed within the apical domain of human radial glia cells (hRGCs) where it lines the wall of the developing cortical ventricular zone colocalizing with the tight junction-associated protein and MAGUK family member TJP1. In a cortical organoid model of SYNGAP1 haploinsufficiency, we show dysregulated cytoskeletal dynamics that impair the scaffolding and division plane of hRGCs, resulting in disrupted lamination of the cortical plate and accelerated maturation of cortical projection neurons. Overall, the discovery of the expression and function of SYNGAP1 in cortical progenitor cells reframes our understanding of the pathophysiology of SYNGAP1-related disorders and, more broadly, underscores the importance of dissecting the role of synaptic genes associated with neurodevelopmental disorders in distinct cell types across developmental stages.

developmental biology↗

bioRxiv2021

Modular Derivation and Unbiased Single-cell Analysis of Regional Human Hindbrain And Spinal Neurons Enables Discovery of Nuanced Transcriptomic Patterns along Developmental Axes

Our inability to derive the vast neuronal diversity of the posterior central nervous system (pCNS) using human pluripotent stem cells (hPSCs) poses a major impediment to understanding human neurodevelopment and disease in the hindbrain and spinal cord. Here we establish a modular differentiation paradigm that recapitulates patterning along both the rostrocaudal (R/C) and dorsoventral (D/V) axes of the pCNS, enabling derivation of any neuronal phenotype with discrete regional specificity. First, neuromesodermal progenitors (NMPs) with discrete Hox profiles are efficiently converted to pCNS progenitors (pCNSPs). Then by tuning D/V signaling, pCNSPs are directed to ventral Shh-dependent MNs (MNs) and locomotor interneurons (INs) or dorsal TGF-{beta}-dependent proprioceptive INs and TGF-{beta}-independent sensory INs. We applied D/V protocols to NMPs spanning the R/C axis for expansive single-cell RNA-sequencing (scRNAseq) analysis. By implementing a novel computational pipeline comprising sparse non-negative matrix factorization, consensus clustering, and combinatorial gene expression pattern identification, we detect hundreds of transcriptional markers within region-specific neuronal phenotypes, enabling discovery of gene expression patterns along the developmental axes. These findings highlight the potential of these resources to advance a mechanistic understanding of pCNS development, expand the potential and accuracy of in vitro models, and inform novel regenerative therapeutic strategies.

neuroscience↗

bioRxiv2018

A 3D model of human skeletal muscle innervated with stem cell-derived motor neurons enables epsilon-subunit targeted myasthenic syndrome studies

Two-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.

bioengineering↗