Hansang Cho

Engineering neural tissues with controlled cellular organization remains challenging due to the limited ability of conventional bioprinting to regulate cellular anisotropy. Here, we present a blade‐assisted shear‐stimulated bioprinting strategy for fabricating anisotropic and multi‐region neural bioconstructs. A blade integrated near the nozzle generated a defined shear field during extrusion, inducing directional alignment of human neural progenitor cells (hNPCs) within a GelMA/HA/Matrigel bioink. Rheological and process analyses identified shear conditions that maximized cellular alignment while maintaining high viability. Shear‐stimulated bioconstructs exhibited enhanced cytoskeletal organization, neurite extension, and neuronal maturation compared with conventional extrusion printing. Furthermore, the system enabled fabrication of multi‐region cellular–acellular–cellular (CAC) neural architectures, in which the acellular interfacial region prevented uncontrolled cellular intermixing while promoting directed neurite bridging and enhanced neuronal connectivity. Mechanistic analyses suggested activation of mechanosensitive signaling pathways associated with cytoskeletal remodeling and neurogenesis. Collectively, these findings demonstrate that process‐defined shear stimulation can program cellular organization and multi‐region neural architectures during bioprinting, providing a promising platform for engineering structurally organized neural tissues for in vitro applications.

Sleep disturbances are a significant health concern in modern society, with prevalent treatments often leading to limited efficacy and unwanted side effects. Adenosine, a sleep-promoting molecule in the brain, presents a promising target for innovative therapies, yet strategies to augment intracerebral adenosine have remained largely unexamined. This study explores transcranial photobiomodulation (tPBM) as a potential intervention, employing near-infrared (NIR) light to enhance mitochondrial adenosine triphosphate (ATP) synthesis and facilitate adenosine release. Utilizing fiberoptic cannula and electroencephalographic electrodes implanted in mice, we found that tPBM significantly increased non-rapid eye movement (NREM) sleep during and after stimulation compared to sham controls. Enhanced NREM delta power and elevated adenosine concentration in the frontal cortex were confirmed. In vitro experiments further demonstrated that NIR PBM increased cellular ATP production without inducing cytotoxicity. Additionally, a double-blind randomized controlled trial with 40 subjects demonstrated significant reductions in insomnia severity, sleep disturbances, and sleep latency. These findings provide preliminary clinical and translational evidence that tPBM may represent a promising non-pharmacological approach for short-term improvement of sleep disturbances through increased homeostatic pressure.

A 'gut-brain axis' is an intricate bidirectional connection between the gut and the central nervous system, serving as a key pathway for signal exchange. However, current in vitro models do not fully capture these dynamic interactions, limiting mechanistic insight and therapeutic testing. Here, we show a 3D human gut-brain-vascular microphysiological platform that integrates lumenized villus-like intestinal barrier, blood vascular-astrocyte interactions, and brain tissue to model circulation-mediated crosstalk between the gut and brain. Using this system, we demonstrate gut-to-brain signaling by delivering bacterial-derived toxins to the gut compartment, which traverse the gut and neurovascular barriers and trigger neuroinflammatory responses and tau-associated pathology in the brain tissue. Conversely, we show that Alzheimer's- and Parkinson's-relevant stimuli applied to the brain compartment elicit neuroinflammation and disrupt both vascular and intestinal barrier integrity, indicating brain-to-gut feedback. Together, our platform provides a human-relevant tool to dissect mechanisms of bidirectional gut-brain communication and to evaluate therapeutic strategies for neurogastrointestinal disease.

Several epidemiological studies have suggested a possible link between Helicobacter pylori (HP) infection and neurodegenerative diseases. However, in the current research, the mechanistic basis of this association remains unclear due to the complexity of multiple effects triggered by HP infection. Here, we expose in vitro cellular models to HP’s cell-free supernatant (_HPCFS) and perform liquid chromatography–mass spectrometry and inhibition assays to identify potential neurodegenerative risk factors associated with HP. We first confirm that _HPCFS disrupts the integrity of the gut and brain barriers via vacuolating cytotoxin A (VacA) binding to low-density lipoprotein receptor-related protein-1 (LRP1), reducing ZO-1 tight junction protein levels and transmembrane electrical resistance. In addition, _HPCFS activates central innate immune cells, as evidenced by increased expression of inflammatory markers, elevated oxidative stress, the release of neurotoxic factors from microglia and astrocytes. VacA hinders microglial amyloid-beta phagocytosis by blocking LRP1, a key receptor for amyloid-beta clearance. We observe that _HPCFS induces neurodegeneration, as indicated by the presence of phosphorylated tau, phosphorylated alpha-synuclein, synaptic impairment, and neuronal damage. Notably, microglia stimulated with _HPCFS exacerbate neurodegeneration more than direct _HPCFS exposure to neurons. Furthermore, we demonstrate that neuroinflammation and neurodegeneration mediated by _HPCFS are mitigated by an LRP1 antagonist or VacA immunodepletion. This study reveals a cellular mechanism of neurotoxic inflammation through multicellular interactions, paving the way for future therapeutic interventions in HP infection-associated neurodegeneration. Graphical Abstract

Glioblastoma multiforme (GBM) is the most aggressive type of brain tumor, characterized by its heterogeneity in cellular components, including reactive astrocytes and microglia. Since neuroimmune responses like astrogliosis and microgliosis gain recognition as vital factors in brain tumor progression, there is a growing need for clinically relevant models that assess the interactions between astrocytes, microglia, and GBM. Here, a NEuroimmune‐Oncology Microphysiological Analysis Platform (NEO‐MAP) is presented as a “new map” to observe astrocytic scar formation and microgliosis in response to GBM. NEO‐MAP based on pathophysiological principles is designed to replicate the GBM‐glia interactions, multi‐phenotypic microglia activities, scar‐forming astrocytes with chondroitin sulfate proteoglycans (CSPGs) in the extracellular matrix, and the biophysical characteristics of the astrocytic scar barrier. The NEO‐MAP reveals that inhibiting mTORC2 in GBM promotes the proinflammatory transformation of astrocytes and enhanced astrocytic scar formation. Astrocytes that form scars prompted microglia to change from the M2 to M1 phenotype, enhancing chemotherapy sensitivity. Tissues from GBM patients show a significant correlation between reduced mTORC2 activity and increased astrogliosis, alongside a decrease in M2‐polarized microgliosis, aligning with the NEO‐MAP findings. Overall, the NEO‐MAP is foreseen as a clinically significant tool for exploring tumor‐glia interactions, opening avenues for drug development aimed at the tumor microenvironment.

A ‘gut-brain axis’ is an intricate bidirectional connection between the gut and the central nervous system, serving as a key pathway for signal exchange. However, current in vitro models do not fully capture the dynamics of interactions between these organs, which limits mechanistic understanding and therapeutic exploration. Here, we present a 3D human gut-brain vascular (GBV) model that simulates bidirectional communication between these entities, allowing us to investigate disorders originating from both the gut and brain. We created a physiologically relevant gut-brain axis model, creating a 3D villus-like lumenized gut barrier, blood vascular-astrocyte interactions, and brain tissue that mimics neurovascular interactions. Next, we demonstrated gut-to-brain signaling by introducing bacterial-derived toxins into the gut side, allowing the toxins to penetrate the gut barrier and the neurovascular barrier, ultimately reaching the brain and leading to tauopathy, a key indicator of neurodegeneration. We observed brain-to-gut signaling by exposing the brain side to risk factors of Alzheimer’s (AD) and Parkinson’s (PD), which induces neuroinflammation, disrupts the vascular barrier, and subsequently affects gut epithelial integrity. Our gut-brain vascular model is a precisely engineered microphysiological system that emulates the human gut-brain-vascular axis and serves as a translational tool to identify therapeutic targets and evaluate pharmaceuticals for neurological and gastrointestinal disorders.

Escherichia coli K1 (E. coli K1) meningitis early occurs in the gastrointestinal and causes severe damage to the central nervous system, including lifelong neurological complications in survivors. However, the cellular mechanism by which E. coli K1 may cause neuropathies is not well understood due to the lack of relevant human multi-organ models for studying multifaceted systemic inflammation across the gut-brain axis. Here, we reconstruct a multicellular model of the human gut-brain axis to identify the neuropathogenic mechanism driven by E. coli K1-colibactin meningitis. We observed that E. coli K1-genotoxic colibactin induced intestinal and peripheral interleukin 6, causing the blood-brain barrier injury and endothelial inflammation via the p38/p65 pathways. Serpin-E1 from the damaged cerebral endothelia induces reactive astrocytes to release IFN-γ, which reduces microglial phagocytosis of E. coli K1 and exacerbates detrimental neuroinflammation via NLRP3/IL-18 axis. Microglial IL-18 elevates neuronal reactive oxidative stress that worsens DNA double-strand breaks in E. coli K1-infected neurons, leading to H3K4 trimethylation and phosphorylation of alpha-synuclein. Our findings suggest therapeutic strategies for post-bacterial meningitis treatment to potentially prevent the initiation of synucleinopathy.

Cellular senescence, a process that induces irreversible cell cycle arrest in response to diverse stressors, is a primary contributor to aging and age-related diseases. Currently, exposure to hydrogen peroxide is a widely used technique for establishing in vitro cellular senescence models; however, this traditional method is inconsistent, laborious, and ineffective in vivo. To overcome these limitations, we have developed a hydrogen peroxide-releasing hydrogel that can readily and controllably induce senescence in conventional 2-dimensional cell cultures as well as advanced 3-dimensional microphysiological systems. Notably, we have established 2 platforms using our hydrogen peroxide-releasing hydrogel for investigating senolytics, which is a promising innovation in anti-geronic therapy. Conclusively, our advanced model presents a highly promising tool that offers a simple, versatile, convenient, effective, and highly adaptable technique for inducing cellular senescence. This innovation not only lays a crucial foundation for future research on aging but also markedly accelerates the development of novel therapeutic strategies targeting age-related diseases.