Biology subjects

Yoshino, D.

Publications and source records attributed to Yoshino, D..

6 recordsLinked to original sources

bioRxiv2025

Lamin B1 physically regulates neuronal migration by modulating nuclear deformability in the developing cortex

Neuronal migration is a vital process that positions billions of neurons to create a functional brain. To navigate the constrained microenvironments within the cortex, precise control over the nuclear mechanics in migrating neurons is indispensable. Here, we show that Lamin B1 (LB1) regulates neuronal migration by modulating nuclear deformability. Excess LB1 in neurons halted migration without altering laminar identity or overall gene expressions in vivo, while in vitro, it elevated nuclear stiffness and impaired neuronal motility in confined spaces. Moreover, mispositioned neurons resulted in electrophysiological defects in the brain. Computational modeling predicted a temporal relationship between nuclear deformation and enhanced migration velocity, which was validated experimentally through live imaging. Notably, cerebral organoid assays using iPS cells established from patients with LMNB1 duplication exhibited impaired neuronal migration in a human model. Collectively, these findings demonstrate that LB1 is a critical regulator of nuclear mechanics, ensuring the accurate spatiotemporal positioning of neurons.

neuroscience↗

bioRxiv2025

Cell-cultured PDMS vascular model to allow placement of implant devices

BackgroundA stent maintains normal blood flow by expanding a stenotic artery from the inside. Stents currently in clinical use are mechanically sub-optimized and, therefore, exert excessive mechanical stimuli on the vascular wall. This can lead to arterial inflammation and potentially in-stent restenosis. To optimize the force exerted by a stent on the vascular wall, we should understand, reproduce, and analyze in detail the mechanical field to which the stented vessel is exposed. However, to date, no in vitro model has been established that can adequately evaluate the mechanical effects of a stent on the vascular wall and be constructed without relying on a laboratorys know-how. This study aims to develop a three-dimensional in vitro vascular model that allows stent placement and to provide the details of its construction method. MethodsPolydimethylsiloxane (PDMS) was used to mimic the adventitial structure of arteries. Human carotid artery endothelial cells (HCtAECs) were then seeded on the luminal surface and cultured for 24 h to form a confluent monolayer (intima). The constructed model was installed in the flow-exposure culturing system, and hemodynamic stimulation (two types of shear stress (SS); 0.5 Pa and 2.3 Pa) was applied to the HCtAECs inside to reproduce the physiological state of blood vessels. In addition, a self-expanding stent was placed in the model during perfusion culture. ResultsWe examined the performance of the developed model based on quantitative evaluations of endothelial morphology in response to SS and in-stent endothelialization. Exposure to SS for 24 and 48 h caused endothelial orientation and elongation in the direction of flow, confirming the physiological responses of blood vessels. We were also able to quantitatively evaluate endothelial migration (endothelialization) to the stent. DiscussionOur model can reproduce the mechanical field inside the stented blood vessel, including hemodynamic stimuli. Based on the results obtained, the developed cell-cultured vascular model has sufficient performance to be used not only for quantitative evaluation of in-stent endothelialization but also for optimization of the mechanical fields in the stented vessel.

bioengineering↗

bioRxiv2024

Biochemical state in tissue can be detected through ultrasound signal

Three-dimensional (3D) cell cultures, such as spheroids, are indispensable models for investigating cellular behaviors and responses under conditions that closely resemble in vivo environments. Conventional imaging techniques, including optical microscopy, are often limited by penetration depth and phototoxicity, complicating the analysis of structural and biochemical changes within dense 3D systems. This study demonstrates the application of ultrasound imaging for the non-invasive evaluation of internal dynamics in cancer spheroids over a 15-day period. Scattering-based acoustic parameters revealed spatial variations in brightness and density, correlating with cellular proliferation, apoptosis, and necrosis. Brightness values in central regions progressively decreased after Day 3, approaching near-zero by Day 15, reflecting necrotic core formation. Artificial inhibition of myosin contractility significantly influenced these patterns, providing insights into biomechanical contributions to spheroid organization. The findings establish ultrasound imaging as a label-free, high-penetration technique capable of addressing critical challenges in 3D culture analysis, offering new opportunities for studying cellular dynamics and therapeutic responses in spheroids and organoid models.

bioengineering↗

bioRxiv2024

Geometrically-engineered organoid units and their assembly for pre-construction of organ structures

Regenerative medicine is moving from the nascent to the transitional stage as researchers are actively engaged in creating mini-organs from pluripotent stem cells to construct artificial models of physiological and pathological conditions. Currently, mini-organs can express higher-order functions, but their size is limited to the order of a few millimeters. Therefore, one of the ultimate goals of regenerative medicine, "organ replication and transplantation with organoid," remains a major obstacle. 3D bioprinting technology is expected to be an innovative breakthrough in this field, but various issues have been raised, such as cell damage, versatility of bioink, and printing time. In this study, we established a method for fabricating, connecting, and assembling organoid units of various shapes independent of cell type, extracellular matrix, and adhesive composition (unit construction method). We also fabricated kidney tissue-like structures using three types of parenchymal and interstitial cells that compose the human kidney and obtained findings suggesting the possibility of crosstalk between the units. We anticipate that this technique will bring us closer to the realization of highly efficient and rapid fabrication of full-scale organoids that can withstand organ transplantation.

bioengineering↗

bioRxiv2022

Stiffness of primordial germ cells is required for their extravasation in avian embryos

During metastasis intravascularly circulating cancer cells undergo extravasation, which frequently takes place in vascular capillary beds 1-3. It remains poorly understood how the extravasation in the capillary beds is regulated. To address this question, chicken primordial germ cells (PGCs) serve as a powerful model since they circulate in blood stream and extravasate at a specific site of capillary bed near the forming gonad 4-6. The extravasation consists of two steps, the intravascular arrest of cells and their subsequent transmigration through the endothelial lining. We here demonstrate with live imaging at a single cell level in vivo that the arrest of PGCs is predominantly governed by occlusion at a narrow path in the capillary bed. In addition, this occlusion is enabled by a hightened stiffness of the PGCs, revealed by atomic force microscopy indentation analyses. The PGCs stiffness is regulated by actin polymerization: inhibition of the actin function causes not only a failure of PGC occlusion in the capillary bed, but also a failure of PGC colonization in the gonads at later stages. Following the occlusion, PGCs reset their stiffness to soften in order to squeeze through the endothelial lining as they transmigrate. The discovery of F-actin-mediated stiffness in pre-extravasating cells provides a model for understanding of dynamic mechanism by which other cells, including metastasizing cancer cells, extravasate in capillary beds.

developmental biology↗

bioRxiv2020

Mechanical impact on the head has an antihypertensive effect

Physical exercise is known to be beneficial for various brain functions. However, the mechanisms behind the positive effects of exercise on the brain remain to be elucidated. Here we show that passive head motion in hypertensive rats, which reproduces the mechanical accelerations generated in their heads during moderate-velocity treadmill running, decreases the expression of angiotensin II type 1 receptor (AT1R) in astrocytes in the rostral ventrolateral medulla (RVLM), thereby lowering blood pressure. Passive head motion generates interstitial fluid movement that is estimated to exert shear stress with an average magnitude of <1 Pa on the cells in the rat medulla. Fluid shear stress of a sub-Pa magnitude decreases AT1R expression in cultured astrocytes. In hypertensive rats, inhibition of interstitial fluid movement following hydrogel introduction to the RVLM eliminates the antihypertensive effects of passive head motion and treadmill running. Furthermore, vertically oscillating chair riding by hypertensive adult humans, which reproduces the mechanical accelerations generated in their heads during light jogging or fast walking, lowers their blood pressure. Our findings indicate that moderate mechanical intervention can have antihypertensive effects by modulating the function of RVLM astrocytes through interstitial fluid shear stress. We anticipate that mechanical regulation is responsible for a variety of the positive effects of physical exercise on human health, particularly those related to brain functions.

bioengineering↗