Biofabrication

Pluripotent stem cells represent a potentially unlimited cell source for the fabrication of human bioartificial tissues to study and treat degenerative conditions such as type 1 diabetes. Alginate is widely used for mammalian cell immobilization and the primary hydrogel studied for pancreatic islet encapsulation. Rheological properties of alginate solutions or fully gelled forms are unsuitable as support matrix for embedded 3D printing. We describe partially gelled self-healing alginate formulations tuned for embedded 3D printing. Perfusable multi-plane hierarchical networks branching into 10 parallel channels, obtained by 3D printing of Pluronic F127 into the alginate support, show high fidelity to computer-assisted models. Therapeutic {beta}-cell doses (40x106 cells/mL) within centimeter-thick perfusable constructs remained viable for at least 1 week of culture under flow, with rapid insulin secretion detected upon glucose challenges. Stem cell-derived islet clusters cultured in 5-channel contructs for 25 days differentiated towards functional insulin-expressing cells. We describe a novel approach to generate cm-scale perfusable endocrine pancreatic constructs using sacrificial embedded 3D printing into alginate. This approach offers an adaptable platform to engineer perfusable cm-scale functional endocrine pancreatic tissues and potentially other vascularized bioartificial tissues.

Stereolithography (SLA) 3D printing has become increasingly popular for fabricating microfluidic devices, with applications including hydrogel patterning and tissue modeling. In open-channel systems with surface tension-driven flow, 3D-printer-induced discrepancies in channel surface texture can significantly impact fluid flow and device performance. While previous work has focused on comparing different 3D printing methods for microchannel fabrication, the effect of device orientation during SLA printing on microchannel morphology and capillary-driven flow has not been systematically evaluated. Furthermore, there is minimal research elucidating the influence of channel surface texture on the flow of biologically relevant hydrogel precursors commonly used in organ-on-a-chip applications. Herein, we investigated the impact of print orientation on channel morphology, fluid wetting behavior, and fluid flow by comparing laser SLA-based parts where the length of the channel was tilted at 0{degrees}, 15{degrees}, 45{degrees}, or 90{degrees} during printing. We demonstrated that channel floor surface texture is greatly affected by print orientation: the highest axial surface roughness was measured in 15{degrees} printed channels, and the highest axial surface tortuosity-which describes the real length along the surface-was measured in 45{degrees} printed channels. Print angles of 15{degrees} and 45{degrees} also resulted in asymmetric roughness of the channel floor, which caused asymmetric wetting of glycerol solution. Surface tension-driven flow of glycerol solution, agarose precursor solution, and collagen precursor solution was affected by print orientation, in which the 45{degrees} printed flow devices had slowest flow for all test fluids. Root mean square roughness was not a reliable predictor of slower flow; instead, surface tortuosity should be considered. Potential alternatives to better theoretically model how print angle-induced surface texture affects open-channel flow are discussed as well. These findings provide a framework of fabrication considerations for laser SLA printing of open microchannels that can also be applied to other layer-by-layer, vat photopolymerization-based 3D printing technologies.

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.

In vitro reconstruction of human tissue microenvironments that integrate native biochemical and biomechanical cues is essential for disease modelling, regenerative medicine, and personalized therapeutic approaches. However, most currently available engineered matrices fail to recapitulate the complexity and tissue specificity of the human extracellular matrix (ECM). To address this limitation, we developed a novel hydrogel derived from decellularized human adipose tissue (atdECM) designed to support three-dimensional culture of human cells. The decellularization and delipidation processes were first validated, and the biochemical composition and biomechanical properties of atdECM were comprehensively characterized. Human pancreatic organoids were then cultured within atdECM hydrogel, and their structural organization and transcriptional profiles were analyzed and compared with those obtained in Matrigel, the current gold-standard matrix for organoid culture. Proteomic and cytokine analyses demonstrated efficient decellularization while preserving collagen-rich ECM architecture and a diverse repertoire of soluble bioactive factors. AtdECM exhibited physiological stiffness and retained tissue-specific extracellular cues. Pancreatic organoids cultured in atdECM displayed morphological similarities with those grown in Matrigel but exhibited transcriptional profiles more consistent with physiological epithelial homeostasis, with reduced activation of inflammatory and stress-related pathways. Altogether, these findings indicate that atdECM provides a human-derived, tissue-relevant, and permissive microenvironment for human organoid generation. This platform represents a promising alternative to Matrigel for studying human tissue biology and for developing physiologically relevant in vitro models.

Accurate cell counting is essential in tissue engineering and cancer research. The ongoing transition towards advanced 3D in vitro tumour models raises a question about the validity of the standard cell counting protocols, particularly in the systems containing extracellular matrix-based scaffolds. Here, we provide a quantitative analysis of the performance of three popular plate reader-based cell counting/viability assays, such as the Alamar Blue, MTT, CellTiter Glo 3D assays, in 2D monolayer and 3D scaffold-based cultures of U251 human glioblastoma cells, including cell-laden Matrigel plugs, and original tissue engineering constructs based on the decellularised sheep brain scaffolds. We quantitatively characterized the assays linearity, precision, biological and technical reproducibility, proportionality, and inter-assay agreement. The study revealed that assays performance is highly platform-dependent, with 2D cultures allowing significantly more precise and reliable measurements than in 3D ECM scaffold-based cultures. The numerical results provided in this study can help researchers make informed decisions when working with 3D scaffold-based in vitro tumour models and for other tissue engineering purposes where precise cell counting is essential. ToC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=184 SRC="FIGDIR/small/720021v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@16018d9org.highwire.dtl.DTLVardef@1ff7d6dorg.highwire.dtl.DTLVardef@838021org.highwire.dtl.DTLVardef@1510d5b_HPS_FORMAT_FIGEXP M_FIG C_FIG

Biomimetic tubular scaffolds hold great promise for tackling unmet clinical needs thanks to their biocompatibility and recapitulation of cellular microenvironments, conferring the ability to promote regeneration. Potential applications include small-diameter vascular implants and grafts for airway repair, for which no viable off-the-shelf solutions currently exist. The tubular materials (4 and 8 mm internal and external diameters) presented here consist purely of type I collagen, contain no chemical crosslinkers, and reproduce the multi-scale architecture of the native tissue including the presence of collagen fibrils. A novel two-step protocol provides materials with distinct concentric layers. A porous external structure, obtained by means of ice templating combined with collagen topotactic fibrillogenesis, favours oriented cell colonization. A smooth and much less porous internal layer provides mechanical and water-tightness properties relevant for in vivo implantation and promotes the formation of an endothelial monolayer under both static and flow conditions. The compliance of the double-layered materials under physiological pressure is close to that of piglet carotid arteries. The materials are also determined to be sufficiently flexible to provide the ability to perform ex vivo anastomosis with bronchi, although the relatively low value of suture retention strength remains a limitation for in vivo suturing.

During development, the size of the neuroepithelial cell pool plays a key role in establishing brain size, determining the numbers of derived progenitors and subsequent neuronal cell types. While early histogenesis is well modelled in brain organoids, the organ-scale geometry of the telencephalon is not accurately recapitulated. Herein, we present a new approach for generating ventral and dorsal forebrain organoids which develop a large ventricular neuroepithelium, characteristic of the closed telencephalic vesicle. Using a growth medium that supports aerobic glycolysis and is typically used for endothelial cells, we modulate neuroepithelial expansion to induce a more anatomically accurate neuroepithelial layer which, upon maturation, thickens physiologically to generate the typical neurogenic layered architecture. In addition, we present a new method for embedding organoids in miniature collagen spheres which mimics native extracellular matrix, stabilizes the ventricular geometry for dynamic culture conditions, and provides a means for incorporating vascular cells for neurovascular development. Finally, we demonstrate that human organoids grown under these conditions exhibit dramatically enlarged ventricles and delayed maturation compared to mouse. Together, this approach provides a model of the forebrain neuroepithelium with morphogenetic macroscale geometry and tissue architecture, suitable for investigating neurodevelopment and disease.

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.

Artificial ovarian scaffolds represent a promising therapeutic strategy for preserving reproductive health in patients. However, current in vitro approaches are limited by inadequate biomimicry of the native tissue microenvironment, leading to poor development of in vitro ovarian models. In this study, we developed region-specific hydrogel scaffolds incorporating solubilized decellularized ovarian extracellular matrix (dECM) with mechanically tuned properties to enhance the functionality of engineered 3D ovarian models. Ovine ovarian dECM was isolated by mechanical and chemical decellularization methods and subsequently solubilized and incorporated in varying concentrations in homogenous alginate (0.5%) and a composite mixture of 1% gelatin with 0.5% alginate (1:1). The synthesized hydrogels were characterized for rheological properties, including Youngs modulus, pore size, and viscosity, and cytocompatibility assays were conducted using Chinese hamster ovary (CHO) cells. The study demonstrated that both 0.5% alginate and the composite gelatin-alginate hydrogels successfully replicated the mechanical properties of native human ovarian cortical and medullary tissue, with Youngs modulus of 0.84 {+/-} 0.16 kPa, pore size (60-150 nm), and toughness of 0.4Pa, respectively. Zonal hydrogel scaffolds incorporating ovarian dECM demonstrated significantly enhanced cell viability compared to hydrogels supplemented with dECM. The study emphasises the critical role of integrating both mechanical and biochemical attributes while developing functional artificial ovarian constructs for transplantation and regenerative medicine applications. This work contributes to advancing strategies for creating physiologically relevant in vitro models of ovarian tissue.

Engineering the human breast in 3D physio-mimetic models is challenging due to its complex multilayered tubular organization, where milk is produced in acini and transported through ductal structures. These functions rely on a highly organized architecture comprising stromal, epithelial, and extracellular matrix compartments. The dysregulation of this architecture perturbs mammary gland homeostasis and promotes the emergence of diverse breast cancer subtypes, from frequent in situ luminal to rarer metastatic basal-like tumors. Despite this knowledge, conventional anti-cancer drug testing still primarily employs high-throughput 3D spheroid models that account for diffusion but lack stromal components, thereby failing to capture stroma-driven treatment resistance. With a unique microfluidic co-extrusion platform, we have developed 3D tubular tissues anchored on a porous and biocompatible alginate shell. Using a one-step protocol, we have bioengineered six relevant ductoid models of healthy and tumoral mammary ducts, most notably a multi-layered model comprising a lumen, mammary epithelium, and stromal compartment made of fibroblasts and matrixes. These new models offer limitless applications in tissue engineering including the characterization of an epithelium and its secretory function, and the identification of the stromal influence on healthy and tumoral mammary gland tissue. Finally, by releasing mechanical constraints, we scale-up the tubular duct model into a mammary assembloid that exhibits branching and budding of acini-like structures from the original duct. We envision that this modular design will broadly impact breast basic and clinical research by opening new experimental avenues toward more physio-mimetic tools through the integration of stromal compartments.

Scaling up microvessel culture systems is essential for producing vascularized clinically relevant tissues, yet current platforms offer little guidance on how to preserve flow conditions during scale-up. Here, we present a computational-experimental framework using computational fluid dynamics (CFD) to guide the design and scaling of microvessel bioreactors. Interstitial flow distributions were pre-dicted in two perfusion-based platforms-a permeable insert and a rhomboidal microfluidic chamber-across multiple scaling factors and hydrostatic pressures. CFD identified IF ranges conducive to vascu-logenesis and quantified how geometry and pressure modulate flow uniformity. Scaled-up bioreactors generated microvessel networks with consistent morphology and connectivity over a 30-fold increase in culture volume, confirming that maintaining equivalent IF ensures reproducible outcomes. The permeable insert platform maintained uniform IF across scales, while the rhomboidal chamber produced spatially varying IF resulting in heterogeneous but physiologically relevant networks. These findings establish CFD as a predictive tool for rationally scaling perfusion bioreactors, enabling microvessel production at clinically relevant scales with controllable morphology. Significance StatementScaling up microvessel bioreactors is critical for engineering large pre-vascularized tissues. However, larger scales may disrupt flow conditions that drive vessel formation. This study demonstrates that computational fluid dynamics (CFD) can predict interstitial flow and guide the rational scale-up while preserving the vasculogenic microenvironment. Experiments across 30+-fold size increase confirmed that matching inter-stitial flow results in morphologically identical microvessel networks. By linking simulation-based design with experimental validation, this work establishes CFD as design tool for scalable perfusion bioreactors for production of microvessel networks at clinically relevant scales.

Engineering three-dimensional neuronal tissues with defined architecture and functional connectivity remains a critical challenge for applications in disease modeling, drug discovery, and regenerative medicine. Recently, a variety of fabrication methods have arisen, such as bioprinting or manual assembly of organoids, but often struggle with scalability, reproducibility, or maintaining cell viability. Here, two scaffold-free acoustic levitation bioreactors are introduced: one optimized for the culture of uniform neuronal spheroids, and another designed for the structuration of assembloids composed of distinct neuronal identities. Using acoustic standing waves, these platforms enable the contactless manipulation of cells and aggregates, facilitating the formation of highly viable functionally mature spheroids. This study shows that both striatal and cortical cell aggregates formed in acoustic levitation self-organize into spheroids within 24 hours and remain viable up to 10 days under these particular culture conditions without medium renewal. These neuro-spheroids demonstrate healthy development with increased growth and typical terminal differentiation and synaptic maturation. Moreover, concentric cortico-striatal assembloids were successfully structured and cultivated using optimized acoustofluidic chips. Offering versatile and scalable tools for engineering complex neuronal networks, acoustic levitation reveals itself as an innovative approach to 3D neuronal tissue modeling, with broad implications for bioengineering, regenerative medicine and fundamental neuroscience research.

Curvature provides essential mechanical cues for epithelial cells, playing a key role in cell differentiation and morphology. Repeatable manufacture of precisely controlled curvature in soft hydrogel materials is therefore essential to study epithelial mechanobiology and function. Multiphoton (MP) based biofabrication holds promise due to its high resolution and three-dimensional design flexibility. Here, we leverage MPs advantages while increasing print speed to develop two complementary tools based on replica molding and multiphoton ablation. These can provide scalable hydrogel curvatures with tunable surface properties relevant for epithelial tissue engineering. In replica molding, MP prints are transferred into PDMS used to pattern centimeter scale arrays in hydrogels. In multiphoton ablation, hydrogels are locally degraded to generate precisely controlled curvatures and surface topography. With both methods, we repeatably guide epithelial cells into alveolar and duct-like shapes. Concave alveolar-like surfaces are shown to enhance the formation of thicker epithelial layers. We observe that surface properties, controlled by both tools, could enhance cytoskeletal organization. Using these biofabrication techniques, individual effects of curvature, surface properties, hydrogel composition, and bulk stiffness on epithelial cells can be studied. Both approaches offer high curvature control and throughput, providing a viable alternative to traditional 3D culture and other printing methods.

Controlled delivery of growth factors and viable cells remains a significant challenge in bone tissue engineering. In this study, a 3D-printed hydrogel scaffold system was developed for the co-delivery of bone morphogenetic protein-9 (BMP-9) and preosteoblasts to enhance bone regeneration. The system consisted of a 3D-printed base scaffold containing BMP-9-coated calcium sulfate (CaS) microparticles and a photocurable hydrogel coating layer encapsulating viable cells. The scaffold design exploited electrostatic interactions between BMP-9 and gelatin matrices by incorporating gelatin type B in the base scaffold and gelatin type A in the coating layer. Differences in the isoelectric points of these gelatin types were utilized to regulate protein binding and release. Release studies demonstrated that CaS microparticles alone exhibited rapid burst release, with nearly 80% of BMP-9 released within 24 h. Encapsulation of BMP-9 coated CaS particles in the 3D-printed scaffolds reduced the release rate, while the addition of the coating layer significantly improved sustained release, limiting BMP-9 release to approximately 50-60% by day 5. Bioactivity studies showed enhanced cell attachment in BMP-9 containing scaffolds compared with controls. Live/Dead cytotoxicity assays demonstrated high cell viability (>80%) within the coating layer over the culture period, confirming that the encapsulation and photocuring processes did not adversely affect cell survival. Cell proliferation and differentiation were further evaluated using WST-1 and alkaline phosphatase assays. The results demonstrate that electrostatic interactions governed by gelatin type selection can regulate BMP-9 release while maintaining high cell viability, providing a promising platform for growth factors and cell delivery in bone tissue engineering.

Endocrine disruptors (EDs) are an exogenous group of compounds associated with thyroid malfunctioning in the human body. Nonetheless, there are currently no adequate in vivo or in vitro models for the preclinical testing of these compounds since both animal and two-dimensional (2D) cell-based models are not able to mimic thyroid physiological conditions from both functional and three-dimensional (3D) organization perspective. Recently, bioprinting technologies emerged as an innovative tool in the field of regenerative medicine and advanced 3D in vitro models that allow the creation of 3D well-organized structures able to mirror physiologically relevant tissue and organ architectures. In this study, we evaluated microfluidic bioprinting as a biofabrication technology to develop a 3D in vitro model of the thyroid gland. We studied the fundamental parameters to obtain a fine control over the bioprinted fibres for different biomaterials. Then, we assessed the possibility to bioprint single thyroid cells, thyroid spheroids and finally mouse embryonic stem cell-derived thyroid follicles. The different cell types maintained high viability and metabolic activity. The bioprinted thyroid model showed high expression of different early and late functional markers and to be responsive to ED exposure. These bioprinted thyroid constructs could provide a new set of advanced 3D in vitro models to test potential EDs and possible adverse outcomes that may be associated with their administration or exposure.

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.

Three-dimensional (3D) bioprinted liver scaffolds offer a promising platform for drug screening, disease modelling, and regenerative medicine, yet their broader adoption is limited by the absence of robust post-fabrication preservation strategies. This study aimed to evaluate the impact of -80{degrees}C (deep freezer) preservation and evaluate the structural integrity and hepatic functionality of GelMA-decellularized liver extra cellular matrix (dECM)-based 3D bioprinted liver scaffolds. Bioinks were formulated using synthesized GelMA and solubilized rat liver dECM, and 3D scaffolds were fabricated via extrusion bioprinting into rectilinear grid scaffolds. The 3D scaffold preservations was performed by immersion into two different medium (the culture DMEM media and the other FBS-DMSO cocktail) was evaluated using MTT viability assay, and albumin assay. Preserved 3D bioprinted scaffolds retained overall architecture and cell distribution in the FBS-DMSO cocktail demonstrated by the live dead assay. Together, the data demonstrate that -80{degrees}C storage can maintain the basic cell viability ([~]80%) and a substantial fraction of liver-specific functionality in 3D bioprinted scaffolds but also highlight sensitivity to preservation-induced injury. These findings underscore the need for further optimization of cryoprotectant formulations and freezing protocols tailored to 3D bioprinted liver scaffolds, and provide a foundational framework for developing ready-to-use, cryopreserved 3D liver models for translational applications.

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.

Vascularization remains a major obstacle in tissue engineering. Here, we introduce a developmentally inspired bioprinting strategy to generate centimeter-scale, self-organising "mother vessel" constructs from iPSC-derived human mesodermal progenitor cells (hiMPCs). By systematically optimizing the bioink composition, we identified a formulation that combines high print fidelity, mechanical stability and cell compatibility within a single-step bioprinting process. Within the first week after printing, hiMPCs in the "mother vessel" constructs underwent spontaneous differentiation and morphogenesis, forming intima-, media-, and adventitia-like layers containing CD31 endothelial, SMA mural and CD34/CD150 progenitor cells. Remarkably, Iba1 macrophage-like cells appeared despite their absence in the initial population, indicating intrinsic differentiation into both vascular and non-vascular lineages essential for angiogenesis, remodeling and tissue homeostasis. Surrounding the newly formed vessel wall-like structure was a broad, vascularized mesodermal tissue compartment that also contained the above-mentioned progenitors. Co-culture with prevascularized mesodermal organoids resulted in early structural interconnection of microvessels with the printed wall, representing a prerequisite for subsequent hierarchical vascular network formation. As a proof-of-concept, the mother vessel withstood controlled flow conditions in a bioreactor without detectable leakage, demonstrating its principal suitability for perfusion analyses. Together, these findings establish a biologically driven platform that bridges macro- and microvascularization. This may pave the way toward perfusable, vascularized larger tissue constructs, a major bottleneck in regenerative biofabrication.

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.