Biology subjects

Szczot, M.

Publications and source records attributed to Szczot, M..

7 recordsLinked to original sources

bioRxiv2026

An Innervated and Vascularized HNSCC-on-a-Chip Model Built on Defined and Tunable Engineered Extracellular Matrices

Understanding the tumor microenvironment (TME) requires experimental platforms that faithfully recapitulate its key components. Here, we present an innervated and vascularized head and neck squamous cell carcinoma (HNSCC)-on-a-chip platform built with fully defined and tunable engineered extracellular matrices (eECMs). In a stepwise increase of complexity, we first co-cultured patient-derived HNSCC cells, cancer-associated fibroblasts, and endothelial cells within tailored eECMs, revealing matrix-dependent differences in self-organization and chemotherapeutic sensitivity. We then integrated these 3D constructs into a cancer-vasculature-interface, which enabled analysis of eECM-dependent directional collective migration and metastatization. Finally, we incorporated HNSCC-specific innervation through injectable 3D human bioengineered trigeminal ganglia, establishing a chip-based innervation-tumor-vasculature tri-interface. Together, this all-human platform captures fundamental determinants of HNSCC progression, including a fully defined ECM, vasculature, and innervation, within a single modular system that is broadly adaptable for interrogating how the tumor microenvironment shapes solid tumor behavior and therapeutic responses. TeaserHNSCC-on-a-chip integrates defined ECM, vasculature, and innervation to investigate tumor behavior and therapeutic responses.

bioengineering↗

bioRxiv2025

Hierarchical organization of mechano-nociceptive pathways revealed by activity labeling

Noxious mechanical stimuli give rise to distinct percepts, from sharp cutaneous pain to diffuse visceral discomfort, yet the nociceptor ensembles that underlie these differences remain poorly defined. We mapped the peripheral architecture of nociceptive signaling by combining in vivo activity labeling of pelvic nerve afferents with single-cell RNA sequencing. Noxious stimuli recruited diverse classes of mechano-nociceptors, but stimulus type exerted modest influence on the composition of activated ensembles. Instead, tissue identity imposed the dominant organizational structure: stimulation of cutaneous and deep pelvic tissues engaged distinct subsets of both myelinated and unmyelinated neurons, revealing a clear domain-level division. Within this architecture, we identified a bladder-innervating myelinated nociceptor subtype with distinctive molecular features, illustrating an additional layer of refinement. Functional imaging and anatomical tracing corroborated this multilevel organization. These findings reveal a hierarchical organization of peripheral mechanical pain encoding, in which mechano-nociceptor populations are differentially engaged according to tissue domain and organ context.

neuroscience↗

bioRxiv2025

Central role for fast nociceptors in mechanical nocifensive behavior and sensitization

Nociceptors, primary afferent nerve fibers that signal noxious stimuli, are broadly divided into slowly conducting unmyelinated C fibers and fast-conducting myelinated A fibers. Whereas C-nociceptors have been extensively studied, considerably less is known about the function of A-nociceptors. To address this gap, we developed an intersectional genetic approach for robust and selective interrogation and manipulation of mechanically responsive A-nociceptors (A-MNs) in mice. Optogenetic A-MN stimulation induced rapid and precise withdrawal reflexes as well as place aversion and facial expression changes consistent with pain affect, while inhibition strongly impaired mechanical nociceptive withdrawal reflexes, demonstrating that A-MNs are necessary and sufficient for rapid avoidance of noxious mechanical stimuli. Prolonged A-MN activation induced mechanical allodynia and central sensitization. In a rare individual lacking thickly myelinated A{beta} fibers, mechanical withdrawal reflexes were completely absent, and pain perception reduced. Together, these findings identify fast-conducting mechano-nociceptors as essential drivers of nocifensive behaviors in mice and humans.

neuroscience↗

bioRxiv2025

Genetic targeting of myelinated primary afferent neurons using a new NefhCreERT2 knock-in mouse

Primary afferent neurons that convey somatosensory modalities comprise two large, heterogeneous populations: small-diameter neurons that give rise to slowly conducting unmyelinated axonal C fibers and medium-to-large diameter neurons with fast myelinated A fibers. Despite these two major groupings, tools to differentiate between unmyelinated and myelinated primary afferent fibers by genetic targeting have not been available; in particular, whereas numerous mouse driver lines exist to target different C fiber populations, genetic tools that target myelinated primary afferent populations are scarce. Here we describe a knock-in mouse line expressing tamoxifen-dependent CreERT2 under control of the Nefh gene, which encodes neurofilament heavy chain (NFH or NF200), a protein that is highly enriched in myelinated fibers. This mouse enables highly selective and efficient recombination of Cre-dependent reporters for functional and anatomical interrogation of myelinated fibers while excluding unmyelinated C fibers. In combination with other recombinase-expressing mouse lines, this genetic tool will be valuable for intersectional targeting of subpopulations of myelinated primary afferent fibers.

neuroscience↗

bioRxiv2025

A fast nociceptive subsystem mediating rapid reflexive behavior but not affective pain

Spinal nociceptive withdrawal reflexes are widely believed to rely on unmyelinated and thinly myelinated nociceptive fibers that also signal affective and motivational aspects of pain. Here we discover a population of myelinated mechanoreceptive nociceptor that forms free nerve endings as well as circumferential endings around hair follicles, and exclusively terminate in the deep spinal dorsal horn. Optogenetic activation of these fibers triggers rapid withdrawal reflexes that are precise and selective for the targeted limb, while silencing increases the threshold of mechanical nociceptive withdrawal reflexes. By contrast, optogenetic stimulation of the fibers is not associated with place aversion nor with changes in facial expression. Thus, we conclude that this nerve fiber population is uniquely positioned to rapidly respond to mechanical threats via selective withdrawal of the targeted body part, whereas other fast and slow nociceptive pathways are required for affective-motivational aspects of pain.

neuroscience↗

bioRxiv2023

PIEZO2-dependent rapid pain system in humans and mice.

The PIEZO2 ion channel is critical for transducing light touch into neural signals but is not considered necessary for transducing acute pain in humans. Here, we discovered an exception - a form of mechanical pain evoked by hair pulling. Based on observations in a rare group of individuals with PIEZO2 deficiency syndrome, we demonstrated that hair-pull pain is dependent on PIEZO2 transduction. Studies in control participants showed that hair-pull pain triggered a distinct nocifensive response, including a nociceptive reflex. Observations in rare A{beta} deafferented individuals and nerve conduction block studies in control participants revealed that hair-pull pain perception is dependent on A{beta} input. Single-unit axonal recordings revealed that a class of cooling-responsive myelinated nociceptors in human skin is selectively tuned to painful hair-pull stimuli. Further, we pharmacologically mapped these nociceptors to a specific transcriptomic class. Finally, using functional imaging in mice, we demonstrated that in a homologous nociceptor, Piezo2 is necessary for high-sensitivity, robust activation by hair-pull stimuli. Together, we have demonstrated that hair-pulling evokes a distinct type of pain with conserved behavioral, neural, and molecular features across humans and mice.

neuroscience↗

bioRxiv2019

HESC-derived sensory neurons reveal an unexpected role for PIEZO2 in nociceptor mechanotransduction

Somatosensation, the detection and transduction of external and internal stimuli, has fascinated scientists for centuries. But still, some of the mechanisms how distinct stimuli are detected and transduced are not entirely understood. Over the past decade major progress has increased our understanding in areas such as mechanotransduction or sensory neuron classification. Additionally, the accessibility to human pluripotent stem cells and the possibility to generate and study human sensory neurons has enriched the somatosensory research field.\n\nBased on our previous work, the generation of functional human mechanoreceptors, we describe here the generation of hESC-derived nociceptor-like cells. We show that by varying the differentiation strategy, we can produce different nociceptive subpopulations. One protocol in particular allowed the generation of a sensory neuron population, homogeneously expressing TRPV1, a prototypical marker for nociceptors. Accordingly, we find the cells to homogenously respond to capsaicin, to become sensitized upon inflammatory stimuli, and to respond to temperature stimulation.\n\nSurprisingly, all of the generated subtypes show mechano-nociceptive characteristics and, quite unexpectedly, loss of mechanotransduction in the absence of PIEZO2.

neuroscience↗