Biology subjects

Clement, B. F.

Publications and source records attributed to Clement, B. F..

7 recordsLinked to original sources

bioRxiv2026

A three-compartment microfluidic platform for investigating signal transmission in the human sensory pathway

Neuropathic pain remains a significant challenge due to limited understanding of sensory signal transmission mechanisms along the sensory pathway. The sensory pathway involves peripheral nociceptors in the dorsal root ganglia (DRG) that transmit signals from skin to the central nervous system via dorsal horn neurons. Current in vitro models lack the compartmentalization and resolution needed to investigate signal modulation at distinct anatomical sites along this pathway. Here, we developed a three-compartment microfluidic platform combining human induced pluripotent stem cell (iPSC)-derived sensory neurons (hiSNs) with human primary epidermal keratinocytes (HPEKs) and iPSC-derived dorsal horn neurons (hiDHNs) in a spatially organized arrangement. The platform integrates polydimethylsiloxane (PDMS) axon-guiding microstructures with high-density microelectrode arrays (HD-MEAs), enabling single-axon electrophysiological recordings and sub-cellular level stimulation. We established viable co-cultures maintained for up to six weeks and characterized spontaneous activity across all conditions. Keratinocytes increased the number of active sensory neuron axons and their firing rates, demonstrating peripheral modulation of neuronal activity. Systematic frequency-dependent electrical stimulation revealed low-pass filtering properties at sensory neuron somata, with filtering characteristics modulated by co-culture with keratinocytes. This platform enables compartment-specific investigation of signal processing in the human sensory pathway and provides a tool for studying neuropathic pain mechanisms and testing potential therapeutics.

bioengineering↗

bioRxiv2025

MyeliMAP: Studying Oligodendrocyte Function in Brain Networks

Oligodendrocytes are the myelinating glia of the central nervous system (CNS), essential for rapid signal propagation, metabolic support, and neuronal health. While rodent-based cultures and organoid systems have provided insights into oligodendrocyte biology, they fall short of capturing human-specific features of myelination or integrating structural and functional readouts. Here, we present MyeliMAP (Myelination MAPping), a human pluripotent stem cell (hPSC) -derived microphysiological and electrophysiological platform that enables robust modeling of CNS myelination. The system combines inducible hPSC-derived neurons and oligodendrocytes in a custom-engineered microfluidic microstructure designed to mimic the developing brain microenvironment, promoting spatially organized axon-glia interactions and controlled myelin sheath formation. Within six weeks, we demonstrate myelin formation and maturation by immunofluorescence and ultrastructural validation using transmission electron microscopy (TEM), confirming compact multilayered wrapping of human axons. Importantly, the microstructure is directly integrated with a high-density microelectrode array (HD-MEA), enabling real-time, long-term functional assessment of network activity and myelin-dependent changes in signal conduction. This allowed us to demonstrate that oligodendrocyte-based myelinated neurons display enhanced conduction velocity of action potentials compared to neuron monocultures. Moreover, the presence of oligodendrocytes stabilized the temporal neuronal network activity by reducing variability in firing patterns and enhancing synchrony across the culture. This dual structure-function approach surpasses static end-point analyses by coupling morphological validation with dynamic, quantitative measurements of maturing circuit physiology. MyeliMAP provides a reproducible, human-relevant platform to dissect neuron-glia interactions and accelerate discovery of remyelination-promoting strategies for CNS disease.

neuroscience↗

bioRxiv2025

HydroMEA: A 3D Hydrogel Based Microfluidic Device to Study Electrophysiology for Myelinated Nerve-on-Chip

Engineered in vitro platforms are powerful systems to study information flow in the nervous system. While existing polydimethylsiloxane (PDMS)-based microfluidic platforms offer precise architectures, the cultured neurons grow on two-dimensional (2D) planar multielectrode arrays (MEA). To mimic the native microenvironment, where neurons grow in three-dimensional (3D) extracellular matrices (ECM), 3D hydrogels can be designed to encapsulate cells and enable physiologically-mimicked behaviors. Here, we describe hydroMEA, a 3D platform fabricated by placing PDMS microstructures on a high-density MEA and filled with a desired hydrogel, to offer controlled topologies, physiologically-relevant microenvironments, and real-time electrophysiological measurements. First, we developed a gelatin methacryloyl (GelMA) hydrogel with incorporated ECM components and tuned the mechanical properties to match those of nerve tissue. The hydrogel was able to support: 1) the growth of iPSC-derived sensory neurons (hSNs) for >100 days; 2) co-cultures of hSN with human embryonic stem cell-derived Schwann cells (hSCs), to enable reliable 3D myelination. Next, hydroMEA were prepared for topologically- defined 3D growth and myelination in designated compartments. Finally, electrophysiological evaluation of hSN-hSCs co-cultures revealed increased conduction speeds indicating functional myelin. This platform is a promising tool to study cell-cell interactions and to functionally evaluate the effect of pharmacological compounds in a more translational manner.

bioengineering↗

bioRxiv2025

An in vitro platform for characterizing axonal electrophysiology of individual human iPSC-derived nociceptors

Current treatments against severe forms of neuropathic pain demonstrate insufficient efficacy or lead to unwanted side effects as they fail to specifically target the affected nociceptors - a specialized subclass of sensory neurons conveying potentially damaging stimuli information to the central nervous system. Neuropathic pain may involve different nociceptor subtypes in different patients. Tools that can distinguish nociceptive axons would enable a more targeted compound screening. Therefore, we developed an in vitro platform combining a CMOS-based high-density microelectrode array with a polydimethylsiloxane (PDMS) guiding microstructure that captures the electrophysiological responses of nociceptors. Human induced pluripotent stem cell-derived (iPSC) nociceptors were cultured at low density with axons distributed through parallel 4 x 10 {micro}m microchannels exiting the seeding well before converging to a bigger axon-collecting channel. This configuration allowed the measurement of stimulation-induced responses of individual axons. Nociceptors were found to exhibit a great diversity of electrophysiological response profiles that can be classified into different functional archetypes. Moreover, we show that some responses are affected by applying the TRPV1 agonist capsaicin. Overall, results using our platform demonstrate that we were able to distinguish nociceptive axons from different subtypes. The platform provides a promising tool for screening potential candidates for nociceptor-specific drugs.

bioengineering↗

bioRxiv2024

Constructing well-defined neural networks of multiple cell types by picking and placing of neuronal spheroids using FluidFM

Controlled placement of single cells, spheroids and organoids is important for in vitro research, especially for bottom-up biology and for lab-on-a-chip and organ-on-a-chip applications. This study utilised FluidFM technology in order to automatically pick and place neuronal spheroids and single cells. Both single cells and spheroids of interest could be selected using light microscopy or fluorescent staining. A process flow was developed to automatically pick and pattern these neurons on flat surfaces, as well as to deposit them into polydimethylsiloxane microstructures on microelectrode arrays. It was shown that highly accurate and reproducible neuronal circuits can be built using the FluidFM automated workflow.

neuroscience↗

bioRxiv2024

An implantable biohybrid nerve model towards synaptic deep brain stimulation

Restoring functional vision in blind patients lacking a healthy optic nerve requires bypassing retinal circuits, ideally, by directly stimulating the visual thalamus. However, available deep brain stimulation electrodes do not provide the resolution required for vision restoration. We developed an implantable biohybrid nerve model designed for synaptic stimulation of deep brain targets. The interface combines a stretchable stimulation array with an aligned microfluidic axon guidance system seeded with neural spheroids to facilitate the development of a 3 mm long nerve-like structure. A bioresorbable hydrogel nerve conduit was used as a bridge between the tissue and the biohybrid implant. We demonstrated stimulation of spheroids within the biohybrid structure in vitro and used high-density CMOS microelectrode arrays to show faithful activity conduction across the device. Finally, implantation of the biohybrid nerve onto the mouse cortex showed that neural spheroids grow axons in vivo and remain functionally active for more than 22 days post-implantation.

bioengineering↗

bioRxiv2024

Engineering an in vitro retinothalamic nerve model

Understanding the retinogeniculate pathway in vitro can offer insights into its development and potential for future therapeutic applications. This study presents a Polydimethylsiloxane-based two-chamber system with axon guidance channels, designed to replicate unidirectional retinogeniculate signal transmission in vitro. The system enables the formation of up to 20 identical functional retinothalamic networks on a single transparent microelectrode array. Using embryonic rat retinas, we developed a model where retinal spheroids innervate thalamic targets through up to 6 mm long microfluidic channels. We found that network integrity depends on channel length, with 0.5-2 mm channels maintaining over 90 % morphological and 40 % functional integrity. A reduced network integrity was recorded in longer channels. The results indicate a notable reduction in forward spike propagation in channels longer than 4 mm. Additionally, spike conduction fidelity decreased with increasing channel length. Yet, stimulation-induced thalamic target activity remained unaffected by channel length. Finally, we assessed the impact of stimulation frequency and channel length on the sustainability of the thalamic target spheroid response. The study found that a sustained thalamic calcium response could be elicited with stimulation frequencies up to 31 Hz, with higher frequencies leading to transient responses. In conclusion, this study shows how channel length affects retina to brain network formation and signal transmission in vitro.

neuroscience↗