Acta Biomaterialia

Dissection of the thoracic aorta includes delamination of medial lamellae and permeation of blood within the media. Quantifying how biaxial loading of a vulnerable wall and fluid mechanics interact to drive dissection remains a central challenge. Here we combine controlled distension-extension testing of intact porcine descending thoracic aortas with forced intramural fluid injection to investigate how axial stretch, injection rate, and needle gauge modulate the initiation and propagation of intramural delamination. Across experiments, injection pressure-volume curves exhibited nonlinear responses characterized by pressure peaks followed by stepwise pressure drops, suggesting progressive micro-delamination events within the medial lamellar networks. Increasing axial stretch significantly elevated peak injection pressure and promoted preferential axial propagation of the permeation / delamination front. Higher injection rates induced abrupt lamellar separation and larger dissected areas, whereas smaller needle gauges generated higher upstream pressures due to increased hydraulic resistance. Synchrotron imaging revealed the microstructural transition from intralamellar fluid permeation and wall swelling to the formation of a large fluid-filled delamination cavity. These results support a mechanistic framework in which the introduction of pressurized fluid within the aortic media behaves as a hydraulic fracture process in a layered poroelastic tissue, governed by balance across fluid pressurization, wall loading, and interlamellar strength. The findings provide quantitative insight into the biomechanical conditions that contribute to the initiation and propagation of aortic dissection.

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.

Patellar osteochondral allograft (OCA) transplantation is widely used to treat large full-thickness cartilage defects, yet long-term failure and reoperation rates remain high. Although surface congruity and osseous integration are emphasized clinically, cartilage thickness and mechanical compatibility between donor and recipient are not considered. Our previous work suggests that cartilage thickness mismatch can amplify local deformation at the graft boundary, potentially compromising graft longevity. This study investigates how combined mismatches in cartilage thickness and mechanical properties influence the local strain environment at the patellar OCA interface. Simplified two-dimensional axisymmetric finite element models of patellar OCA repair were developed in ABAQUS. Donor-to-recipient cartilage thickness ratios ranging from 0.33 to 3.25 were evaluated together with donor-recipient Youngs modulus mismatches (2.5-7.0 MPa). Cartilage was modeled using homogeneous linear elastic and functionally graded material formulations to account for depth-dependent stiffness. A compressive pressure of 1.0 MPa was applied to represent patellofemoral joint loading, and peak compressive and shear strains were quantified at the graft boundary. Cartilage thickness mismatch produced localized high-strain regions (HSR) of compressive and shear strain at the donor-recipient interface that were absent in thickness-matched constructs. Strain amplification increased with both thickness and mechanical property mismatch. Compressive strain exhibited directional asymmetry, with donor-side-thicker configurations producing greater amplification than recipient-side-thicker configurations. Incorporating depth-dependent cartilage stiffness reduced peak strain magnitudes but did not eliminate mismatch-driven strain amplification. These findings demonstrate that cartilage thickness and mechanical disparity can create HSR at the patellar OCA graft boundary that may predispose grafts to impaired integration and long-term failure.

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

The mechanical behavior of right ventricular (RV) myocardium is governed by its anisotropic microstructure, yet constitutive models that account for fiber dispersion and enable reliable parameter identification remain limited. In this study, we propose a physics-embedded constitutive neural network framework for automated discovery of strain energy functions and microstructural parameters from experimental data. The model is formulated within an incompressible, orthotropic hyperelastic setting using invariant-based representations. Fiber, sheet, and normal directions are incorporated through a rotated structural basis, and dispersion effects are modeled using a generalized structure tensor approach. The framework is trained on multi-axial mechanical data from ovine RV myocardium, including uniaxial tension-compression and simple shear tests. We investigate two training scenarios: (i) full datasets containing both tensile and compressive regimes and (ii) datasets restricted to tensile loading. In both cases, the model accurately reproduces the measured stress-strain responses and identifies sparse, interpretable constitutive models which involve isotropic, anisotropic, and coupling invariants. However, the identifiability of microstructural parameters strongly depends on the available loading conditions. While tensile-only data yield higher predictive accuracy, they result in non-unique or biased estimates of fiber dispersion. In contrast, inclusion of compressive data enables consistent identification of dispersion parameters by separating fiber and matrix contributions. These results highlight the importance of multi-axial loading data for robust parameter identification and demonstrate the capability of constitutive neural network-based approaches for data-driven modeling of anisotropic soft tissues.

Ancestry-associated immune differences influence fibrosis risk, however, how fibrosis-associated pathways vary across individuals remains poorly understood. Fibroblasts are a main cell type involved in fibrosis. The fibroblast response is shaped by cytokine signaling and macrophage activation. The extent to which these pathways vary across individuals, and how ancestry-associated immune differences influence fibrosis risk, remains poorly understood. Here, a poly(ethylene glycol) (PEG)-based hydrogel microphysiological system was leveraged to model fibroblast-macrophage interactions following oxidative stress and to integrate donor-specific immune signals using matched macrophages and serum. Individuals of self-reported African ancestry exhibited higher monocyte expression of CCL4, lower monocyte expression of OXER1, and increased serum IL-10, compared to individuals of European ancestry. Within the hydrogel, oxidative stress reduced fibroblast prevalence while inducing Ki67 and p16. Exogenous TGF-{beta}1 increased fibroblast prevalence and collagen 3 production but did not independently increase -SMA. Incorporating donor-specific macrophages and serum revealed that cultures from individuals of European ancestry demonstrated higher fibroblast -SMA and p16 expression. Pharmacologic inhibition of IL-10 further increased -SMA, particularly in African ancestry-derived cultures, identifying IL-10 as a key protective signal limiting fibroblast activation. This hydrogel system provides a platform for dissecting inter-individual immune variation and identifying mechanisms underlying ancestry-associated fibrosis risk.

Hydrogels are the preferred materials for applications mimicking soft tissues due to their high water content and tunable mechanical properties. The state of the water in these hydrated networks governs their response to mechanical loading through coupled interstitial flow and large deformations of the solid network. Reliable experimental methods for quantifying the fraction of mobile fluid during mechanical deformation remain limited. Within the theoretical framework of mixture theory, we describe hydrogels as hydrated biphasic media consisting of a deformable incompressible solid matrix and a mobile fluid phase. We developed a mechanical testing protocol that enables the experimental separation of solid and fluid contributions under loading. The method is demonstrated using biocompatible and highly versatile hydrogel phantoms of varying compositions. Controlled, incremental drained confined compression of the hydrogel samples results in free-water fractions of approximately 40%, 60%, and 77%, reflecting the systematic influence of the polymer content on the porosity and fluid mobility. Comparison with cryo-SEM-derived surface porosity reveals statistically significant differences and highlights the scale-dependent sensitivity of surface measurements compared to bulk measurements. This study introduces a new mechanical method for quantifying the free-water fraction in macroporous, ultrasoft, highly hydrated biomaterials. Furthermore, the multi-step protocols enable the separation of dissipative, fluid-related relaxation from the equilibrium response of the solid skeleton, allowing direct calibration of constitutive models for macroporous soft solids. The proposed method provides a reliable basis for the development and optimization of hydrogels for applications where fluid transport is critical, such as neural interfaces, bioelectronic platforms, and tissue-engineered constructs.

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.

Cell migration is fundamental to various biological processes, including morphogenesis, wound healing, and cancer metastasis. Durotaxis--directed migration of cells in response to spatial variations in stiffness--has been extensively studied using engineered substrates with prescribed stiffness. However, recent work has increasingly shifted toward understanding cell migration in fibrous matrices that can be actively remodeled by the actomyosin contractility, as commonly observed in tumor and epithelial cells. Despite these advances, a theoretical framework explaining how cells structurally remodel their surrounding matrix to promote their own durotaxis, and which cellular forces govern this behavior, remains elusive. To address this gap, we developed a biomechanical model in which polarized cells contract and migrate over a fibrous matrix. Using this model, we first confirmed that cells on an externally strained matrix preferentially migrate along the direction of applied strain. Then, we investigated how cells autonomously remodel the matrix to create stiffness patterns favorable for durotaxis. In the presence of intercellular adhesion, cells acted collectively to stiffen the matrix, after which a small subset of cells escaped the main population and migrated outward. This behavior is reminiscent of intravasation during cancer metastasis, where cohesive cell clusters generate local matrix remodeling that facilitates the departure of more motile subpopulations. These results illustrate how matrix stiffening driven by cell cohesion and contractility regulates durotactic behavior and provide mechanistic insight into collective invasion processes relevant to cancer metastasis.

IntroductionCancer progression is driven not only by tumor cells but also by interactions between the extracellular matrix (ECM), stromal cells, and immune cells within the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are major drivers of ECM remodeling, assembling ECM with aberrant organization. Extra domain A fibronectin (EDA-FN), a cellular FN containing an extra type III domain, is upregulated in the TME. EDA-FN regulates cellular behavior and has been associated with poor patient prognosis. Macrophages are among the most abundant immune cells within the TME, where they contribute to TME remodeling and inflammation to promote cancer cell invasion and metastasis. However, how tumor-associated matrix-specific cues regulate macrophage behavior remains largely understudied. PurposeHere, we developed a fibroblast-derived matrix platform that captures the structural imprint of tumor-associated EDA-enriched matrices and investigated how matrix-specific cues regulate macrophage behavior in the absence of ongoing soluble factor cues. MethodHuman mammary fibroblasts (HMFs) preconditioned in incubated low-serum media (lNC, or control) and MDA-MB231 metastatic breast cancer cell-conditioned media (mTCM) were cultured on polyacrylamide gels of 2 kPa and 20 kPa, respectively, followed by decellularization. Matrix organization, including fiber alignment, width, and intrafibrillar spacing, was quantified from confocal images. Decellularized EDA-FN-enriched matrices were subsequently reseeded with macrophages to assess macrophage morphology, phenotype, and matrix interactions. ResultsThe combined effects of tumor-derived soluble factors and pathological stiffness induced a CAF-like phenotype in HMFs, accompanied by cytoskeletal reorganization and microarchitectural alterations of EDA-FN-enriched matrices. Tumor-associated matrices exhibited increased alignment, narrower fiber width, and enlarged intrafibrillar spacing compared to control matrices. These aberrant, tumor-associated matrix-derived features were associated with altered macrophage behavior, including heterogeneous morphology, enhanced localized EDA-FN matrix loss beneath the cell body, and a hybrid phenotype with a shift toward a CD206-dominant profile. ConclusionsThese findings demonstrate the feasibility of obtaining EDA-FN-enriched matrices to isolate matrix-specific cues for investigating macrophage-ECM interactions. Furthermore, this platform can be leveraged to identify matrix-targeting therapeutic approaches for modulating macrophage function within the TME.

Idiopathic pulmonary fibrosis (IPF) is a progressive and ultimately fatal disease of aging, driven by dysregulated fibroblast activation and accompanied by collagen accumulation in the lung interstitium, resulting in tissue stiffening. While the accumulation of senescent cells has been increasingly implicated in IPF pathogenesis, understanding the reciprocal dynamics of senescent fibroblast levels and evolving tissue mechanics is difficult to achieve with experimental approaches alone. To address this limitation, we developed an agent-based model (ABM) of fibroblast activation in the lung that couples cell behavior to the dynamic mechanical changes accompanying fibrosis. This model was parameterized entirely from experimental data in young mice to enable robust validation and then adapted to fit aged mouse biology for additional validation. Both young and aged models accurately reflected changes in collagen accumulation and stiffness burden of experimental systems. We then incorporated senescent cell behavior into the aged model to investigate how senescent cell burden influences fibrosis progression and how cell-cell interactions drive senescent cell accumulation. These simulations identified a unique role for juxtacrine-mediated contact between non-senescent and senescent fibroblasts in expanding the total senescent cell burden. Our ABM also revealed that the timing of immune-mediated senescent cell clearance critically regulates fibrotic outcomes. Together, this ABM provides useful insights into how the interrelated dynamics of tissue mechanics and senescent fibroblasts drive fibrosis progression.

Various ankle-foot conditions (e.g., fractures, diabetic foot ulcers, and post-surgical recovery) require periods of complete non-weightbearing followed by gradually increasing partial loadings. However, existing assistive devices often provide inconsistent or uncomfortable offloading during gait. Additionally, prolonged proximal leg offloading can contribute to muscle atrophy, reduced bone density, and overuse of other body segments. We present a novel offloading ankle-foot orthosis (OLAFO) designed to overcome these limitations. The OLAFO features a patient-specific load-bearing shank brace, designed through a digital workflow and fabricated from a 3D-printed core reinforced with carbon-fiber composite lamination. Interlocking serrated side struts, adjustable in 2 mm increments, modulate load sharing between the shank and plantar surfaces. Furthermore, the OLAFO incorporates contact plates with a rocker profile informed by roll-over-shape measurements to support forward progression and gait symmetry. Proof-of-concept biomechanical verification in one able-bodied participant evaluated complete offloading, five partial-loading levels, and normal gait using a pressure walkway to compute vertical ground reaction forces and impulses. In complete offloading, the affected foot generated no contact pressures. Across partial-loading levels, the foot impulse increased from 14% to 53% of the total load and scaled linearly with strut height adjustments, supporting clinician-prescribed loading increments. Contralateral stance duration increased only modestly compared to commonly used assistive devices, indicating reduced compensatory loading on the intact limb. These findings demonstrate the proof-of-concept feasibility of the OLAFO, highlighting its potential for verifying full offloading and prescribing partial-loading targets during rehabilitation. Future research will evaluate performance across patient populations and clinical rehabilitation tasks.

Osteoporotic bone degeneration involves progressive deterioration of trabecular microarchitecture, yet most scaffold-based bone tissue engineering studies evaluate osteogenesis in structurally favorable architectures that poorly represent compromised bone environments. Here, we establish a degeneration-inspired Voronoi scaffold platform in which point spacing serves as a single tunable architectural parameter to model transitions from dense mechanically integrated to severely deteriorated trabecular-like microenvironments. Increasing point spacing from 1.25 to 2.5 mm progressively reduced scaffold connectivity and stiffness while shifting deformation behavior from distributed load transfer to localized stress concentration, as confirmed by finite element analysis and mechanical testing. Benchmarking against clinically reported HR-pQCT datasets from postmenopausal women demonstrated that the intermediate 1.75 mm point spacing scaffold represents a clinically relevant compromised trabecular-like state, whereas the 2.5 mm scaffold represents a more severely deteriorated architectural condition. These architecture-dependent mechanical and structural transitions directly regulated hMSC behavior, where high point spacing scaffolds reduced cytoskeletal organization, stress fiber density, and osteogenic mineralization, establishing an architecture-associated osteogenic dysfunction regime. Polydopamine (PDA) coating progressively enhanced cytoskeletal organization and mineralization within architecturally compromised scaffolds without altering scaffold geometry. To quantitatively assess biointerface-mediated functional recovery, a Mineralization Rescue Percentage (MRP) framework was introduced, demonstrating up to 43% restoration of architecture-associated mineralization loss following PDA coating. Collectively, this work establishes a clinically contextualized degeneration-to-rescue biomaterials framework that shifts current scaffold design paradigms beyond structurally favorable architectures toward systematic investigation and functional rescue of architecture-associated osteogenic dysfunction within compromised bone-like microenvironments. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/725650v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@26833forg.highwire.dtl.DTLVardef@72b2b7org.highwire.dtl.DTLVardef@333083org.highwire.dtl.DTLVardef@b5f2d1_HPS_FORMAT_FIGEXP M_FIG C_FIG Statement of SignificanceMost scaffold-based bone tissue engineering studies evaluate osteogenesis in structurally favorable architectures that poorly represent compromised bone microenvironments associated with osteoporosis. Here, a clinically contextualized Voronoi scaffold platform is established in which point spacing serves as a single tunable architectural parameter to model transitions from mechanically integrated to structurally deteriorated trabecular-like states. By decoupling architectural and surface biointerface effects, the study demonstrates that architectural deterioration alone can drive cytoskeletal disruption and osteogenic failure. Importantly, polydopamine-mediated surface engineering partially restored cytoskeletal organization and mineralization within architecturally compromised scaffolds without altering bulk geometry. A Mineralization Rescue Percentage (MRP) framework was further introduced to quantitatively assess biointerface-mediated functional recovery within degeneration-inspired scaffold microenvironments.

Pathologic arterial stiffening is a hallmark of vascular disease that contributes to maladaptive vascular remodeling and neointimal hyperplasia through vascular smooth muscle cell (VSMC) phenotypic switching. Yet, because vascular disease progression is governed by both biomechanical and extracellular matrix (ECM) alterations, existing in vitro models often fail to recapitulate the full complexity of the diseased vascular microenvironment. Here, we developed a bioactive decellularized extracellular matrix (dECM) and methacrylated hyaluronic acid (MeHA) composite scaffold platform with tunable stiffness that preserves native vascular ECM components while enabling controlled investigation of stiffness-dependent cell behavior. Proteomic analyses confirmed retention of key vascular matrisome components, including collagens and glycoproteins, following decellularization. Electrospun vascular dECM scaffolds maintained an aligned fibrous architecture and spanned stiffness ranges representative of healthy and pathologically stiffened arterial microenvironments. Within this matrix-preserving platform, human VSMCs cultured on stiff dECM scaffolds exhibited increased spreading, altered morphology, enhanced nuclear localization of YAP and survivin, and broad transcriptional changes consistent with a shift toward a proliferative, matrix-remodeling VSMC phenotype. Together, this bioactive, matrix-preserving platform enables mechanobiologically relevant modeling of stiffness-driven vascular remodeling and indicates YAP and survivin as candidate regulators of maladaptive VSMC mechanotransduction.

Granular scaffolds have emerged as promising platforms for tissue regeneration, offering injectability and cell-scale porosity that support robust cell infiltration and tissue formation. However, the isotropic pore structure of spherical building blocks does not provide the directional cues needed to guide organized tissue formation. Addressing this requires asking not just whether granular scaffolds can be made anisotropic, but whether directional cues persist across the pore network at scales relevant to cell behavior. Using high aspect ratio GelMA hydrogel fibers as building blocks, we demonstrate that spherical granular materials lose orientational coherence at the cellular scale, confirming that isotropic building blocks are fundamentally incapable of providing structural guidance beyond individual pore neighborhoods. In contrast, fibrous building blocks extend persistence into the multicellular range, occupying an intermediate architectural regime exhibiting locally coherent but globally variable organization, rather than simple isotropic or uniaxial alignment, that has previously been inaccessible to granular scaffold design. We show this regime is functionally meaningful: myotubes undergo contact guidance through locally persistent but globally variable pore structure, and greater persistence is associated with increased myotube elongation and multinucleation in primary human muscle progenitor cells. Together these results expand the design space for granular scaffolds beyond pore size and porosity, and establish persistence as a variable linking granular scaffold architecture to organized tissue formation.

The vascular system exhibits complex, non-planar geometries that become further distorted during pathological remodeling, including arterial tortuosity and aneurysms. Although hemodynamic shear stress is a well-established regulator of vascular function, the direct effects of curvature as an intrinsic geometric cue remain poorly defined. This is largely because existing in vitro models are static and fail to capture the dynamic changes that accompany disease progression. To address this gap, we used a magnetoactive hydrogel platform that enables real-time, on-demand curvature of endothelial monolayers to reproduce clinically established tortuosity metrics. Using this system, we found that elevated curvature increased nuclear localization of yes-associated protein (YAP), with the strongest response in convex relative to concave regions of highly tortuous endothelial monolayers. This mechanosensitive response was accompanied by reduced VE-Cadherin junctional thickness and increased membrane localization of endothelial nitric oxide synthase. Together, these findings identify local curvature, independent of shear stress, as a regulator of endothelial cell mechanosensing and function, and establish a dynamic hydrogel platform for isolating geometric regulation from shear stress inputs in vascular mechanobiology.

Focal injuries to articular cartilage in load-bearing joints fail to heal and often progress to degeneration, underscoring the need for repair strategies that result in restored cartilage structure and function rather than fibrocartilage formation. Granular extracellular matrix (gECM) hydrogels, flowable grafts composed of densely-packed matrix particles, offer a promising approach but lack long-term functional validation in large-animal models. Here, we developed a flowable gECM hydrogel composed of decellularized cartilage microparticles incorporated within a thiol-functionalized hyaluronan matrix. Proteomic analysis confirmed enrichment of cartilage-specific gECM matrisome components. When implanted into critical-sized femoral condyle defects in a goat model and evaluated 12 months post-implantation, both gECM hydrogel and microdrilling (surgical controls) achieved >80% defect filling. However, in contrast to microdrilling, gECM repair tissue exhibited surface tribological (friction, adhesion) and compressive mechanical properties comparable to native cartilage, with a similar proteoglycan-to-collagen ratio, enrichment of type II collagen, minimal type I collagen (typical of a fibrous scar), improved quantitative MRI metrics, and evidence of lateral cartilage integration and subchondral bone remodeling. Together, these findings demonstrate that a flowable gECM hydrogel supports integrative, cartilage-like repair in a load-bearing joint, supporting advancement of this approach toward clinical translation. One Sentence SummaryA granular ECM hydrogel implanted in a goat condyle provided a robust repair, filling the defect tissue with integrated, hyaline-like cartilage at 12 months.

Nanoclay-based biomaterials offer promise for localised growth factor presentation, yet their in vivo degradation, clearance, and systemic fate remain poorly defined. Here, we investigate the fate of a synthetic nanoclay-BMP-2 gel during ectopic bone induction using a combination of in vivo imaging, histology, and component-resolved elemental analysis. Fluorescent tracking confirmed prolonged localisation of BMP-2 within the nanoclay gel and robust bone induction despite negligible growth-factor release. Inductively coupled plasma mass spectrometry (ICP-MS) revealed divergent clearance kinetics for lithium and silicon, structurally distinct components of the clay crystalline lattice, indicating decoupled ionic and particulate degradation pathways. Early clearance was dominated by cell-mediated fragmentation and the transport of clay particulates, while later stages involved preferential lithium release associated with local clay dissolution as well as integration within newly formed bone. Systemic biodistribution analysis demonstrated rapid, transient lithium release into circulation with renal clearance, contrasted with initial hepatic and then later-phase renal handling of silicon species. Together, these findings define a multiphasic in vivo clearance model for nanoclay biomaterials consistent with progressive remodelling, localised BMP-2 activity and, importantly, safe systemic handling. This work provides mechanistic insight into the activity and clearance of nanoclay-based regenerative therapies and establishes the importance of component-resolved tracking for evaluating the biodistribution of degradable inorganic biomaterials.

The combination of synthetic biology and additive manufacturing has driven major changes in production of biomaterials, especially through the use of three-dimensional (3D) bioprinting to create engineered living materials. However, current fabrication methods can be limited by prohibitive hardware costs and the inability to maintain structural fidelity in complex, free-form living architectures. This work demonstrates how to build a low-cost, open-source 3D bioprinting platform that can make complicated bacterial structures with complex geometry and high dimensional accuracy. A commercially available, conventional fused deposition modeling 3D printer was modified to create a bioprinting system that is simple to build. The modified bioprinter, which costs around $450, is less expensive than many commercial bioprinters. This 3D-printing technology uses slurry-based support bath methods featuring low-cost gelatin and agarose microparticles, resulting in structures with a high aspect ratio (>8:1) and feature sizes as small as 260 m. The optimization of critical printing settings, including the ability of the bioink to retract during non-print movements, resulted in a reduction of unwanted bacterial deposition by nearly two orders of magnitude. Long-term viability experiments showed that bacteria in the bioprints could survive for at least 28 days with nutrient supplementation. Additionally, 3D-printed engineered biofilms revealed that incubation conditions and extracellular matrix composition significantly impacted the mechanical properties of printed constructs, with tradeoffs between matrix production and mechanical integrity. This study showcases an accessible 3D bioprinting platform for advanced bioprinting technologies, enabling development of engineered living materials with potential applications in synthetic biology, biotechnology, and tissue engineering.

Hygroscopic surfaces act as local vapor sinks that reshape the condensation field around them, but whether distributed biological structures do the same has not been investigated. We have established that hyphae of fungal colonies functionally behave as vapor sinks, creating a dry region of width{delta} around themselves when placed on a cooled substrate. In addition, the radial distribution of droplet sizes steepens during condensation, and the rate at which droplets evaporate locally after chamber drying increases. In order to quantify this behavior, we employed a combination of time-resolved imaging and survival analysis to determine how long individual droplets persist on the surface surrounding the colony. These data were used to derive three quantitative measures of the vapor-sink effect. Each measure was found to be directly proportional to the vapor-sink strength of the substrate, as calibrated against NaCl-agar hydrogels of known water activity (LOOCV RMSE = 0.031 for recovered aw). These findings were consistent across three fungal genera (35 experiments), and all species fell along calibration lines defined by the hydrogel standards. This result is consistent with a diffusion-limited vapor-depletion framework. The measured genus-level{delta} ratios agreed to within 6% of predictions from structural absorbing capacity, and field measurements on Gymnosporangium-infected apple leaves were consistent with the same signatures under natural conditions. These results establish a non-contact method for inferring the material properties of thin hygroscopic biological surfaces from their condensation patterns.