Biology subjects

Heidari, H.

Publications and source records attributed to Heidari, H..

3 recordsLinked to original sources

bioRxiv2026

Photopatterned spatiotemporal organisation and in situ differentiation of 3D human cortical networks

Modelling human cortical microcircuitry in vitro requires platforms that recapitulate both the compositional complexity and spatial architecture of developing neural tissue. Current organoid and assembloid models often rely on the bulk fusion of pre-differentiated, region-specific cells, lacking the capacity for emergent spatial co-differentiation and microenvironment-driven multiscale organisation. There is also a lack of neural and neuronal-glial models with photo-architectured network geometries. To address these limitations, we present a volumetric in situ differentiation system using a triculture of precision reprogrammed human iPSC-derived glutamatergic neurons, GABAergic neurons and astrocytes embedded throughout ultra-soft photocrosslinkable hydrogel microenvironments. The deterministic and spatially controlled method allows us to engineer macro-scale, interconnected human neural networks directly onto functional microelectrode array interfaces using projection photopatterning for high-throughput screening. Unlike fusion-based organoids and assembloids, our platform enables simultaneous, spatially distributed lineage differentiation and maturation, and extensive topography-guided neurite outgrowth bridging localised cellular hubs to recapitulate various aspects of neurodevelopmental patterning and synaptic integration in 3D. The model enables topographic patterning of neuronal-glial networks as well as 3D cell-embedded bioprinting with the developed triculture system. Both modes of cellular growth are studied and demonstrated here. Longitudinal electrophysiological tracking over a month of culture reveals a transition from immature, quiescent states to asynchronous, information-dense microcircuits characterised by an expanded state-space manifold and physiological excitatory-inhibitory balance. By replicating the mechanics of native brain parenchyma, the model presents a highly reproducible, scalable and flexible platform for the study of cortical microcircuitry development, neurodegenerative decline, and inter-regional network assembly.

bioengineering↗

bioRxiv2025

Biocompatible PVDF Nanofibers with Embedded Magnetite Nanodiscs Enable Wireless Magnetoelectric Neuromodulation

Wireless neuromodulation technologies aim to eliminate the need for invasive hardware and enhance tissue compatibility. Magnetoelectric (ME) materials enable magnetic field-induced electrical stimulation, offering a minimally invasive neural activation. However, conventional ME systems use rigid ceramic components with limited biocompatibility. Here, we report a flexible, predominantly organic ME platform composed of polyvinylidene fluoride (PVDF) nanofibers embedded with anisotropic magnetite nanodiscs (MNDs). These MNDs were selected for their unique ability to exert magnetic torque due to vortex magnetization, and their intrinsic magnetostrictive behaviour. The resulting ME fibers preserve the piezoelectric {beta}-phase of PVDF and exhibit magnetoelectric voltage coefficient of 1.26 Vcm-{superscript 1}Oe-{superscript 1}. We compare two magnetic activation strategies; torque-based and high-frequency magnetostriction, finding that magnetostriction more effectively triggers neuronal responses. In vitro calcium imaging reveals robust activation in primary cortical neurons cultured on ME fibers. Biocompatibility post-stimulation was confirmed on ex vivo human brain tissue, with no increased cell death. Implanted into the premotor cortex of freely moving mice, the fibers enabled wireless modulation of motor behaviour under an alternating magnetic field. This work presents the first demonstration of wireless magnetoelectric neuromodulation using soft, biocompatible fiber composites, paving the way for future bioelectronic interfaces free from rigid components and tethered systems. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=182 SRC="FIGDIR/small/660052v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@7868e7org.highwire.dtl.DTLVardef@12f32a7org.highwire.dtl.DTLVardef@1a6a7e4org.highwire.dtl.DTLVardef@5876e4_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2018

A Multi-layer, Self-aligning Hydrogel Micro-molding Process Offering a Fabrication Route to Perfusable 3D In-Vitro Microvasculature

The in-vitro fabrication of hierarchical biological systems such as human vasculature, which are made up of two or more cell types with intricate co-culture architectures, is by far one of the most complicated challenges that tissue engineers have faced. Here, we introduce a versatile method to create multi-layered, cell-laden hydrogel microstructures with coaxial geometries and heterogeneous mechanical and biological properties. The technique can be used to build in-vitro vascular networks that are fully embedded in hydrogels of physiologically realistic mechanical stiffness. Our technique produces free-standing 3D structures, eliminating rigid polymeric surfaces from the vicinity of cells and allowing layers of multiple cell types to be defined with tailored extracellular matrix (ECM) composition and stiffness, and in direct contact with each other. We demonstrate co-axial geometries with diameters ranging from 200-2000 m and layer thicknesses as small as 50-200 {micro}m in agarose- collagen (AC) composite hydrogels. Coaxial geometries with such fine feature sizes are beyond the capabilities of most bioprinting techniques. A potential application of such a structure is to simulate vascular networks in the brain with endothelial cells surrounded by multiple layers of pericytes and other glial cells. For this purpose, the composition and mechanical properties of the composite AC hydrogels have been optimized for cell viability and biological performance of endothelial and glial cell types in both 2D and 3D culture modes. Multi-layered vascular constructs with an endothelial layer surrounded by layers of glial cells have been fabricated. This prototype in-vitro model resembles vascular geometries and opens the way for complex multi-luminal blood vessels to be fabricated.

bioengineering↗