Biofabrication

Tissue phantoms that mimic microvasculature and perfusion are essential for modelling vascular function, guiding interventions, and calibrating imaging systems, which require faithful replication of vascular geometry and flow. Conventional fabrication strategies, including wire-based molding, lithographic micromachining, and additive manufacturing, offer useful capabilities but remain constrained by predefined designs, rectangular channel cross-sections, limited scalability, and high production costs. Reliance on predefined digital vascular models restricts design flexibility and limits the ability to capture the natural variability and complexity of real vascular systems. Here, we present a lithography-free, fractal-generating approach based on a modified Lifted Hele-Shaw Cell (LHSC) technique, in which vascular networks emerge spontaneously via interfacial fluid instabilities. Unlike pre-designed methods, these structures are governed by fluid properties and flow conditions, enabling adaptive, physiologically relevant geometries with smooth Gaussian cross-sections and natural diameter tapering. We demonstrate four phantom designs: a planar vascular tree, an anatomically guided cerebral network, a retinal vascular model, and a conformable curved substrate phantom. Validation using Laser Speckle Contrast Imaging confirms structural fidelity and physiologically relevant flow consistent with Murrays law. This platform uniquely integrates realistic vascular architecture with emergent, fractal driven formation, highlighting its potential as a reproducible and biologically relevant alternative to conventional vascular phantom fabrication. Furthermore, the availability of such realistic in vitro vascular models can reduce reliance on animal experiments and contribute towards more ethical and sustainable preclinical research.

Over the past decade, the integration of microgel-based granular hydrogels in biomedical technologies has experienced substantial growth due to the numerous benefits microgels offer. However, the inability to easily adopt uniform microgel fabrication workflows at scale constitutes a major bottleneck, or in some cases, a barrier-to-entry that stunts further growth of the field. The gold-standard technique for emulsion-based microgel production is through microfluidic droplet-generating devices that produce liquid gel precursor droplets that gel post-production. However, traditional microfluidic workflows often require multiple independent flows and controlled pressure sources, along with a steep learning curve in using microfluidics to achieve uniform droplet sizes reproducibly and repeatedly. This difficulty in adopting microgel fabrication is further compounded by low throughput and the extensive flow rate calibration required when switching to new formulations (e.g., material type, droplet size). In this work, we present a step-emulsion system that bridges the gap by providing a robust and simple setup. We experimentally characterize and evaluate how flow and outlet channel dimension contribute to the generation of uniform droplet populations at specific sizes. With our large dataset consisting of various outlet channel dimensions, we evaluated outlet channel geometrical impacts (height, width, cross-sectional area, aspect-ratio, etc.) on gel precursor droplet size and generation throughput. We demonstrate robust, highly compatible, and repeatably uniform droplet generation from various gel precursor polymer backbones, users with varying microfluidics experience, and a wide viscosity range, including alginate solutions with 650 times the viscosity of water. Furthermore, we confirmed consistent gel precursor droplet generation outcomes driven by a constant flow source (syringe pump) and by direct manual injection as a simple and highly adoptable option for the generation of gel precursor droplets. This platform is ideal for researchers seeking rapid and easy microgel fabrication, regardless of microfluidics experience.

Human induced pluripotent stem cells (hiPSCs) are the most accessible source material for derivation of stem-cell-based therapies at scale. However, a disconnect exists between quality characteristics of phenotype in the pluripotent state, and downstream metrics for efficacy and safety. Bridging this gap is a major challenge. Given hiPSC plasticity, environmental conditioning plays a crucial role in guiding phenotype. This work presents a parallelizable scale-down approach, acquiring real-time data to inform hiPSC phenotype throughout biomanufacturing. We developed an optoelectronic instrumentation suite capable of measuring pH, dissolved oxygen, and cell density as important surrogates for phenotype in a scale-down expansion bioprocess. We were successful in obtaining continuous, integrated parametric data throughout cultivation and estimating metabolic characteristics of hiPSC phenotype. This system functions as a proof-of-concept tool for development of predictive models and monitoring strategies around the elucidation of phenotypic dynamics within hiPSC biomanufacturing. We have demonstrated a feasible open-source multivariate continuous monitoring approach at research scale that combines common process parameters with a scattering measurement against aggregate density. The combination of these parameters enables surrogate measurement of a metric for metabolic phenotype. This contribution emphasizes monitoring how the bioprocess influences variables important in the context of cell state, in broader pursuit of better understanding the link to downstream functionality and global optima in hiPSC biomanufacturing for regenerative medicine.

Cultivated meat is an emerging biotechnology that aims to produce edible tissues in an ethical and sustainable manner. However, the recreation of skeletal muscle tissue that replicates the protein composition and sensory characteristics of traditional meat is a major challenge. Skeletal muscle tissue engineering requires non-animal-based scaffolds which are inexpensive and food-safe, while meeting specific mechanical requirements with respect to viscosity, stress-relaxation and stiffness. While many of these characteristics can be fulfilled by alginate-based biomaterials, a key limitation of alginate is its lack of intrinsic attachment sites for animal cells, preventing efficient adhesion, differentiation and tissue formation. Here, we established a screening platform to evaluate extracellular matrix (ECM)-mimicking peptides as functionalisations of alginate scaffolds in 2D. Our platform enables high-throughput assessment of cell/peptide interactions, serving as a predictive tool for 3D tissue constructs. Our screen identified two RGD-containing sequences (vitronectin- and fibronectin-mimicking peptides) as most effective in promoting attachment and myogenic fusion of bovine satellite cells. Notably, these peptides outperformed more complex mixtures containing up to seven different ECM-mimicking peptides. Our findings provide a streamlined approach for optimising biomaterial functionalisations for cultivated meat applications, and lay the groundwork for future advancements in scalable, sustainable skeletal muscle tissue engineering.

Postoperative gastric leak after bariatric surgery is a serious complication associated with prolonged treatment, repeated interventions, and substantial morbidity. Endoscopic internal drainage using double pigtail stents is widely adopted. However, current stents, originally designed for biliary use and often based on simple cylindrical geometries, are not optimized for post-bariatric gastric leak anatomy, mechanical support, or fluid drainage. Here, we present BRIDGE (Biodegradable aRchitected Internal DrainaGE), a stent concept integrating triply periodic minimal surface (TPMS) architectures to control mechanical compliance, kink resistance, and drainage performance. Using computational modeling, mechanical testing, and benchtop flow studies, we evaluate TPMS designs and identify volume fraction as a key parameter balancing flexibility, structural integrity, and hydraulic performance. TPMS-integrated designs tolerated a 7.1-fold smaller bend radius than a commercial stent without kinking and achieved up to a 2-fold increase in drainage. We also developed a stereolithography-printable biodegradable resin and fabricated a prototype lattice-integrated stent. TeaserA biodegradable, 3D-printed stent with an architected lattice design improves flexibility, kink resistance, and abscess drainage while eliminating the need for device removal.

Critical-sized bone defects represent a challenge in bone tissue engineering, due to insufficient vascularization that results in implant failure. Scaffold pre-vascularization is a promising strategy to create a functional microvascular network that integrates with host vasculature. In this study, we present a hybrid 3D construct comprising a hyaluronic acid-based hydrogel and a 3D printed polycaprolactone/{beta}-tricalcium phosphate scaffold, to support vascular network formation and osteogenic differentiation. Peptide-functionalized (i.e. RGD, YIGSR, IKVAV, QK) hydrogels were obtained via thiol-ene chemistry, using two crosslinkers (PEG-diSH or MMP-diSH). Preliminary biological experiments assessed human mesenchymal stromal cells (hMSCs), endothelial cells (hUVECs), and their co-culture, on different gel formulations. All cell conditions displayed enhanced spreading and metabolic activity on gel formulations comprising RGD; thus these (i.e. RGD only and a combination of RGD/YIGSR) were selected for further studies. Cells were then mixed with the hydrogel precursor solutions, which were injected to embed the scaffolds and crosslinked using a UV lamp. After 7 days, tubule formation was observed only in co-culture conditions, highlighting the importance of cellular crosstalk for the formation of a vascular network. Significant differences were found across the tested formulations. In the RGD-PEG constructs, hUVECs formed tubule-like structures, surrounded by hMSCs, exhibiting pericyte-like behavior, supported by the upregulation of SMA gene. Conversely, in the RGD/YIGSR-MMP conditions, hMSCs were mostly located on the scaffold fibers, and showed the highest expression of early osteogenic markers (RUNX2 and ALP). Overall, we demonstrated that the hybrid system with tailored hydrogel chemistry can support simultaneous microvascular organization and osteogenic commitment, offering a promising platform for bone tissue engineering applications. However, further studies involving longer culture periods will aim at clarifying the complex interplay between material composition, cell crosstalk and spatial organization and their influence on the maturation and stability of the vascular network.

Background and ObjectivesCardiovascular cells differentiated from human induced pluripotent stem cells (iPSCs), including cardiomyocytes, are valuable for evaluating human cardiac pharmacology and toxicity. Early assessment of cardiotoxicity, especially for novel drugs like anticancer agents, is essential for improving drug development efficiency and reducing costs. This study aimed to develop a highly sensitive bioassay system capable of evaluating the physiological function of human cardiac tissue in vitro. MethodsHuman iPSCs were differentiated into cardiovascular cell types (cardiomyocytes, vascular endothelial cells, and vascular mural cells) and assembled into a cardiac tissue model on aligned fiber device. This tissue was cultured dynamically to induce the formation of vascular network-like structure. By combining the fiber device with our previously developed heart-on-a-chip microdevice (HMD), we created a new model of HMD (Aligned Fiber-based HMD; AF-HMD) with improved throughput and stability. Pulsatile force changes induced by drug exposure were quantified by tracking the displacement of fluorescent microbeads within the microchannels. ResultsAF-HMD demonstrated functional responses to known cardiac agonists and toxicants, such as doxorubicin. The device also replicated clinically relevant cardiotoxic events, including the synergistic effects of trastuzumab and doxorubicin, showing marked reductions in contractile force and beat rate, mirroring clinical observations. ConclusionsThe AF-HMD system provides a sensitive and reproducible platform for evaluating cardiotoxicity in drug development. It offers a promising tool for preclinical screening, with potential applications in personalized medicine and predicting cardiotoxic risk in cancer therapy.

Tracking gastrointestinal (GI) transit in preclinical models is essential for assessing gut motility and drug delivery. Current preclinical methods rely on end-to-end transit measurements or emptying studies that require terminal endpoints and organ explanation. Clinically, radiopaque "Sitz" markers are administered orally and their position in the GI tract is assessed through radiography. Sitz markers have been in use since 1969 and are typically mass-produced using industrial molding or extrusion, resulting in a single, fixed geometry with limited tunability. We present a stereolithography (SLA)-based method to fabricate customizable radiopaque markers using additive manufacturing with a barium sulfate (BaSO4)-doped resin. We demonstrate precise control over marker geometry, a key advantage over existing markers. Furthermore, we apply this method in vivo, tracking markers in a live rat model from ingestion to excretion using serial CT imaging. We systematically investigate how changes in marker geometry impact GI residency and transit time. Our results show that 3D printed markers provide a flexible and tunable platform for radiopaque marker fabrication and enable investigation of the fundamental relationship between a markers physical properties and its performance in a dynamic biological environment. This work establishes a novel, tunable platform for GI motility evaluation and drug delivery studies.

Hydrogels are widely used as three-dimensional cell culture systems to understand the impact of cellular mechanotransduction for tissue engineering applications. Photoinitiated thiol-ene click chemistry is a commonly utilized hydrogel crosslinking mechanism that provides spatial and temporal control over hydrogel network formation and resulting mesh size and compressive properties. Despite historically documented efficiency as step-growth reactions, these reactions do not always proceed as predicted. To understand the impact of cell confinement and microenvironmental mechanics on cellular function, thiol-ene network formation must be thoroughly characterized. To this end, the objective of this work was to investigate the crosslinking dynamics to determine hydrogel network formation as assessed via mesh size and mechanical properties using a pentenoate-functionalized hyaluronic acid thiol-ene reaction. Hydrogel parameters including polymer concentration and thiol:-ene crosslinker molar ratio were modulated (4, 6, or 8 polymer weight percent and 0.15:1, 0.5:1, or 1:1 molar ratio of thiol groups to reactive -ene groups) to tune network properties including shear storage modulus and relative mesh size. Molecular Dynamics (MD) simulations were used to simulate the thiol-ene crosslinking reaction and establish a method for predicting thiol-ene reaction efficiency. Lastly, the feasibility of this hydrogel system for in vitro modeling was confirmed via assessment of metabolic activity of encapsulated primary human meniscal cells.

IntroductionReliable generation of hepatocyte-like cells (HLCs) from pluripotent stem cells remains limited by heterogeneity and incomplete maturation of the cells. Derivation of induced pluripotent- and embryonic stem cells into hepatocytes typically relies on complex, and costly reagent-intensive protocols, with inconsistent reporting of differentiation efficiencies and functional maturation criteria. Variability in protocol designs highlights the need for optimisation, particularly in mouse embryonic stem cells (mESCs) systems that can be more comparable with mouse models for underpinning translational and toxicological studies. Here, we developed and evaluated two cytokine-based strategies: an advanced hepatic-inducing cocktail (A-HIC) and a simplified hepatic-inducing cocktail (HIC), both designed to reduce complexity while increasing functional maturation. MethodsHepatic differentiation and maturation were assessed by morphology, immunofluorescence, flow cytometry, and qRT-PCR. Functional competence was evaluated via urea production, glutathione synthesis, indocyanine green handling, cytochrome P450 inducibility, and impedance-based cell layer integrity monitoring. ResultsMorphological, molecular and phenotypic analyses confirmed that both protocols supported hepatic lineage progression, generating heterogeneous populations of hepatoblast-like and more mature HLCs. Gene expression confirmed the loss of pluripotency, transient endoderm induction, and subsequent hepatic specification. Functionally, cells exhibited glycogen storage, inducible urea production, glutathione depletion, and active ICG uptake and clearance, with stable monolayer formation by day 21. A-HIC-derived HLCs demonstrated enhanced maturation, with higher ASGR1 expression and stronger Cyp1a1 induction. DiscussionThese findings suggest that both protocols generate functional HLCs; however, A-HIC yields a higher proportion of functionally mature cells with reduced variability. This approach enables a simple, cost-effective, and time-efficient generation of HLCs, supported by improved functional characterisation with potential applicability to more complex pluripotent systems, including human iPSC-based models for disease modelling and toxicology.

Cryopreservation offers an option for long-term storage and global distribution of complex in vitro models, yet protocols for multicellular microphysiolgocial systems (MPS) such as brain organoids/spheroids remain limited. Here, we systematically compared three commercially available cryopreservation (mFreSR, CryoStorCS10, and 3dGRO) and two freezing time points, and established a robust workflow for freezing and recovering brain organoids. After defrosting, we assessed morphology and metabolic activity. We also evaluated electrophysiology, calcium transients, and neurite outgrowth. In addition, we measured astrocyte migration, apoptosis, mitochondrial integrity, microglia survival, and neural marker expression. We found that organoids require a 4-week recovery period to regain structural and functional stability. Although organoids frozen at week 6 showed higher metabolic activity after recovery, organoids cryopreserved at week 2 had clearly better functional outcomes. They exhibited stronger spontaneous network firing and maintained calcium transients. Finally, incorporated microglia-like cells survived the freezing and displayed comparable morphology to unfrozen controls. Across the endpoints measured here, 3dGRO showed the most favorable overall performance; formal ranking across media awaits harmonized normalization, single-organoid electrophysiology, and prespecified QC thresholds. Together, these results define a practical and reproducible cryopreservation strategy that preserves key physiological features of brain organoids and supports the establishment of ready-to-use organoid banks. The ability to reliably store and distribute complex brain-like tissues represents an essential step toward global standardization, scalable experimentation, and wider adoption of human-relevant microphysiological systems. Together, these results demonstrate recovery of key physiological features in the subset of organoids that remain viable after thaw and support the feasibility of brain organoid banking.

This study focuses on the development of 3D culture model dedicated to liquid cancers drug screening. The challenge addressed was to effectively retain non adherent small cells within a 3D-scaffold with tailorable mechanical properties, while proposing a fast and effective tool for drug screening. To that aim, we developed a macroporous alginate-chitosan polyelectrolyte complex (PEC) scaffold combined with a low-viscosity alginate (LVA) cell seeding solution. We hypothesized that LVA could undergo in situ pore gelation via calcium ions retained from the PEC fabrication process, enabling effective retention and homogeneous cell distribution, leading to an improved platform for drug screening and personalized medicine. First, we evaluated scaffold suitability for LVA infiltration and gelation. Microtomography revealed a highly porous architecture (98%) enabling LVA homogeneous penetration and complete gelation within 30 min, as confirmed by SEM, microscopy, rheology, and micro-rheology. Next, we assessed cell retention and biocompatibility using primary human chronic lymphocytic leukemia (CLL) cells. LVA-assisted seeding increased cell density 2.6-fold compared to medium alone, with homogeneous distribution, >80% viability over 7 days, and preserved differentiation into nurse-like cells. Finally, we demonstrated a proof of concept for drug screening. The Alginate-PEC scaffold (A-PEC scaffold) supported both qualitative live/dead imaging and rapid quantitative viability measurement with the Alamar Blue assay. Drug responses reproduced microenvironment-dependent protection effects observed in vivo. This integrated scaffold and seeding method provides a promising 3D platform for in vitro liquid cancer studies and drug screening on patient-derived hematological cancer cells. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=67 SRC="FIGDIR/small/722037v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@9b71d4org.highwire.dtl.DTLVardef@14e1dd0org.highwire.dtl.DTLVardef@1876a56org.highwire.dtl.DTLVardef@15656bc_HPS_FORMAT_FIGEXP M_FIG C_FIG

Three-dimensional stem cell-derived neural organoids provide a promising platform for investigating early brain development and interregional circuit formation. Although co-culture of region-specific organoids into assembloids has enabled the study of cortical and subcortical interactions, these models lack directional specificity and spatial control, limiting their ability to recapitulate canonical circuit architecture. Here, we present a microfluidic platform for constructing directional and tunable interregional circuits while preserving anatomical distinction. This system, which we term "directoids" incorporates micropatterned polydimethylsiloxane (PDMS) microstructures to control uni- and bidirectional axonal growth between cortical and thalamic organoids. We observed a 70.4% success rate of axons traversing the full channel length in the permissive direction and reaching the opposing organoid, whereas no neurites successfully crossed the probative direction. These results demonstrate robust directionally bias in axon outgrowth and establish a scalable, reproducible strategy for controlling asymmetric connectivity between anatomically distinct neural organoids. Using high-density CMOS microelectrode arrays, we further validated directional tuning of extracellular action potential propagation within directoid microchannels, a feature not observed in straight-channel connectoid controls. Directoids also exhibited significant asymmetry in firing rates between channel entry and exit sites, consistent with engineered bias in signal flow. This provides an experimental paradigm for dissecting how anatomical connectivity and functional activity converge to shape neuronal networks. Together, these findings establish a microfluidic platform for investigating the mechanisms underlying hierarchical circuit formation, regional specification, and functional integration in developing human neural organoid models at cellular resolution not possible in vivo.

Biodegradable electrospun nanofiber (NF) scaffolds have emerged as promising materials for tissue engineering applications, including vascular grafts, because their mechanical properties and degradability can be tuned. However, their in vivo degradation behavior remains poorly understood. In this study, we characterized the in vivo degradation profiles of representative biodegradable NF materials widely used in small-caliber vascular graft research, namely polycaprolactone (PCL), poly(D,L-lactide) (PLA), polyglycolic acid (PGA), and a PCL/PLA blend, by monitoring molecular weight changes in subcutaneous and vascular environments. Electrospun NF sheets were implanted subcutaneously in mice, and tubular NF grafts were implanted into the abdominal aorta of rats. Samples were harvested for up to 48 weeks after implantation and analyzed primarily by size-exclusion chromatography (SEC) to assess time-dependent changes in molecular weight. Scanning electron microscopy (SEM) and solid-state 13C nuclear magnetic resonance (NMR) were additionally performed to evaluate ultrastructural and chemical changes associated with degradation. SEC analysis revealed distinct material-specific degradation patterns. PCL showed the slowest degradation and retained a relatively high weight-average molecular weight (Mw) in both environments. PLA exhibited marked environment dependence, with near-complete degradation in the subcutaneous environment by 48 weeks, whereas scaffold structure was maintained in the vascular environment. The PCL/PLA blend showed earlier reduction in the high-molecular-weight fraction than PCL, indicating faster scaffold breakdown. PGA degraded most rapidly and could not be evaluated beyond 2 weeks in the subcutaneous model or in the vascular model because of early graft rupture. SEM analysis further demonstrated that progressive loss of fibrous ultrastructure over time was a common feature across all materials. In addition, NF scaffolds became resistant to organic solvent after implantation in vivo, and solid-state 13C NMR analysis of the solvent-insoluble fractions detected polymer-derived signals together with additional signals consistent with biological constituents. These findings indicate that in vivo degradation of biodegradable NF scaffolds is material dependent, environment dependent, and more complex than simple hydrolytic chain cleavage alone. This study provides a quantitative framework for evaluating NF degradability and offers new insight into the design of biodegradable vascular grafts. HighlightsO_LISEC quantified long-term in vivo degradation of PCL, PLA, PGA, and PCL/PLA. C_LIO_LIDegradation was both material dependent and implantation environment dependent. C_LIO_LIIn vivo nanofiber degradation involved structural and chemical changes beyond hydrolysis. C_LI

Oligodendrocyte-enriched cortical organoids (OCOs) are a powerful platform for modeling oligodendrogenesis in a human cellular context. However, neuronal activity is impaired in conventional culture media, limiting assessment of neuronal function in conjunction with oligodendrocyte biology. To address this, we used a modified BrainPhys medium termed neuronal activity medium (NAM) and defined the optimal developmental window for NAM exposure to generate OCOs with robust neuronal activity (NAM-OCOs). Stage-specific exposure to NAM, prior to oligodendrocyte expansion, leads to enhanced structural maturation, as evidenced by increased organoid size, heightened synaptogenesis, and upregulation of transcripts associated with neuronal complexity. Further, NAM-OCOs display increased cellular heterogeneity, including greater representation of GABAergic interneurons while preserving oligodendrocyte development and maturation. Altogether, our studies demonstrate that stage-specific exposure to an activity-permissive environment enhances neuronal activity, establishing an OCO model which integrates neuronal activity with oligodendrocyte development and maturation. HighlightsO_LIIncreased neuronal activity in oligodendrocyte-enriched cortical organoids (OCOs) C_LIO_LIStage-specific Neuronal Activity Medium (NAM) optimizes activity C_LIO_LINAM-OCOs display increased cellular heterogeneity and neuronal maturation C_LIO_LIOligodendrogenesis is preserved in NAM-OCOs C_LI eTOC blurbIn this article, Chung et al enhance neuronal activity in oligodendrocyte-enriched cortical organoids (OCOs) through stage-specific exposure to Neuronal Activity Medium (NAM). OCOs exposed to NAM display elevated cellular heterogeneity, structural maturation, and synaptogenesis, while preserving oligodendrocyte development and maturation. These results establish an increasingly comprehensive OCO model for studying neuronal function and oligodendrogenesis.

Tissue engineered constructs are increasingly used for both modeling organs and disease in vitro as well as for therapeutic intervention. In addition to collagen, these constructs commonly include native extracellular matrix proteins (ECM), such as fibronectin and laminin. Given the critical role of inflammatory pathways in disease and in response to implanted materials, it is important to understand the role these proteins play in regulating the inflammatory environment. Fibronectin and laminin influence neutrophil function and endothelial activation in 2D, but their regulation of the inflammatory environment in 3D engineered constructs is not clear. For this study, we used an inflammation-on-a-chip device that includes a model blood vessel surrounded by a collagen I hydrogel with fibronectin and/or laminin. We investigated the additive effects of both proteins and a range of concentrations for each protein to determine concentration dependence. Both fibronectin and laminin have concertation dependent effects on neutrophils and the endothelium. High concentrations (50 {micro}g/mL) of fibronectin reduced neutrophil migration, while 20 {micro}g/mL laminin reduced neutrophil extravasation and migration, potentially due to lower ICAM-1 expression by the endothelium. Interestingly, 50 {micro}g/mL of laminin significantly disrupted endothelial vessel formation and reduced ICAM-1 and VE-cadherin expression, likely due to significant changes in the collagen architecture. The inclusion of fibronectin and laminin, even at physiological levels, results in significant effects on neutrophil behavior, endothelial vessel formation, and collagen architecture. These proteins impact the inflammatory environment and thus need to be considered when modeling diseases and designing therapeutics, especially when neutrophils or an endothelium are involved. Translational Impact StatementThis work uses an inflammation-on-a-chip device to study how fibronectin and laminin impact neutrophil behavior and vascular inflammation as these proteins are commonly used in engineered constructs. We found that fibronectin impairs neutrophil migration, while laminin decreases neutrophil extravasation and migration and at higher concentrations also prevents endothelial vessel formation. Therefore, researchers should be aware that these proteins will alter the inflammatory environment when including them in engineered constructs.

Biomaterials-based tissue engineering aims to recapitulate native tissue architecture and function for both clinical repair and advanced in vitro models. While improvements in biomaterials have been made, including granular hydrogels and ECM-derived scaffolds, current biomaterials lack intentional design choices for effective translation, including regulatory considerations, practical extrusion delivery, and biomimetic characteristics. Here, we develop and characterize a library of granular ECM (gECM) biomaterials for five key tissues (cartilage, bone, skin, liver, and kidney), in which ECM particles are densely packed within a hyaluronic acid hydrogel. We optimize tissue processing methods that preserve proteomic content and structure while also aligning with scale-up manufacturing and regulatory guidelines. We show that gECM hydrogels can be molded, extruded, and 3D-printed while retaining their shape, and they stabilize at physiological temperature and pH. Lastly, we demonstrate that bulk gECM mechanics are driven by tissue type, and gECM hydrogels support viability, proliferation, and tissue-specific cellular activity. Together, these findings establish gECM hydrogels as a translational and biomimetic platform for clinical tissue repair and complex in vitro models.

Sustainable, biodegradable elastomers are needed to replace fossil-based alternatives and reduce the environmental impact of traditional vibration damping materials. We investigate agarose-based hydrogels as eco-friendly vibration absorbers, examining the combined effects of polymer concentration (1-7 wt%), relative humidity (55-98%), and mechanical pre-stress on their dynamic mechanical properties. Frequency-dependent viscoelastic and vibration transmissibility tests, supported by Gaussian Process Regression (GPR), reveal that increasing agarose concentration enhances the storage modulus (E') by over an order of magnitude, reaching[~] 5 MPa depending on humidity and applied prestress. Remarkably, the damping efficiency--characterised by the loss factor (tan(d))--exhibits a highly non-monotonic trend. Maximum energy dissipation is observed at intermediate network densities, with tan(d) up to 0.21 and a loss modulus of[~] 515 kPa at 5 w% and 75% relative humidity, comparable to synthetic elastomers. GPR analysis shows that prestress controls nonlinear stiffening and transmissibility resonance behavior, while shifting peak damping from 5 wt% to 1 wt% agarose as prestress increases. These findings underscore the mechanical tunability and sustainability of agarose hydrogels, providing potential design guidance for biodegradable vibration mitigation materials.

Reliable and scalable soft implantable neural interface fabrication remains a key challenge for chronic bioelectronic applications. Here, we present a transparent soft microelectrode fabricated with electrohydrodynamic (EHD) printing, utilizing the fluorinated polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly (3, 4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS) to form seamless, selectively patterned multilayer structures with low impedance and long-term stability. Controlled in situ curing during printing yields dense, void-free substrate and encapsulation layers, suppressing interfacial defects and ionic pathways, while maintaining high optical transparency (>60%) with PEDOT:PSS. The printed microelectrodes exhibit low impedance, high charge storage and injection capacities, and stable electrochemical behavior under biomimetic conditions. In addition, the devices demonstrate robust mechanical and electromechanical stability under cyclic deformation in both dry and wet environments, as well as under prolonged electrical stimulation. Accelerated aging studies project multi-year operational lifetimes, and in vitro/in vivo biocompatibility assessments confirm excellent tissue integration. These results establish EHD-printed fluorinated polymer-based microelectrodes as a scalable and durable platform for chronic implantable biointerfaces. ToC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=182 SRC="FIGDIR/small/726391v1_ufig1.gif" ALT="Figure 1"> View larger version (79K): org.highwire.dtl.DTLVardef@152c58aorg.highwire.dtl.DTLVardef@126f1f5org.highwire.dtl.DTLVardef@1d743cforg.highwire.dtl.DTLVardef@1a4d743_HPS_FORMAT_FIGEXP M_FIG C_FIG This report presents an electrohydrodynamically printed transparent soft microelectrode for chronic purposes. Electrohydrodynamic printing promotes seamless multilayer structures with selective deposition and long-term mechanical stability. The devices show low impedance, high charge capacity, and robust electrochemical/electromechanical properties. Accelerated aging projects [~]7.2 year lifetimes, and XPS/SEM-EDS confirm strong ion barrier properties and biocompatibility for chronic implantation.

Co-culturing cells with mismatched densities, where one cell type adheres to surfaces while the other floats, represents a fundamental challenge in cell biology. This is particularly evident in studying macrophage-adipocyte interactions, where macrophages must engage and clear lipid-rich apoptotic adipocytes, a process critical to understanding chronic inflammation in obesity and metabolic disease. The density disparity between macrophages, which sink and adhere to culture surfaces, and adipocytes, which float due to their lipid content, has prevented conventional co-culture approaches from achieving sustained cell-cell contact. To address this challenge, we developed a microfluidic system that confines adipocytes and lipid droplets in close proximity to macrophages. This platform features recessed micro-traps within the upper surface of a microfluidic chamber that trap buoyant objects while allowing media exchange and delivery of reagents for live-cell and immunofluorescence imaging. Time lapse imaging revealed that the dynamic process of macrophages-dead corpse interactions, showing that individual macrophages cannot engulf entire corpses but instead mechanically deform them. Furthermore, the platform successfully recapitulates the formation of Crown-Like Structures (CLS), clusters of macrophages surrounding dead adipocytes that are hallmarks of adipose tissue inflammation. Long-term culture revealed that CLS effectively clear lipids compared to partial macrophage engagement, providing mechanistic insights that were previously unattainable with standard histological approaches. Beyond the macrophage-lipid interaction, this platform has potential for studying interactions between adherent cells and buoyant targets, such as microplastics, opening new avenues for research where density mismatch poses a major barrier.