Biomaterials

Metastasis is the leading cause of cancer-related mortality, yet experimental models inadequately recapitulate the tissue-specific microenvironments that shape metastatic dissemination. In vivo systems provide physiological relevance but are poorly suited for mechanistic studies and screening, whereas conventional in vitro assays lack the organ-specific extracellular matrix (ECM) context that critically influences invasive behavior. To address this gap, an ex vivo method is established that balances biological relevance with scalability, affordability, and ease of use. Mild detergent decellularization of mouse organs followed by vibratome slicing generates optically transparent lung, liver, and intestine scaffolds that preserve native ECM architecture, mechanics, and composition. These organ-derived matrices are readily integrated into standard microfluidic channels and analyzed using conventional fluorescence microscopy, enabling quantitative assessment of cancer cell invasion without specialized infrastructure. Benchmarking with breast cancer cell lines of well-defined invasive capacity confirms the robustness and biological relevance of the platform. Non-invasive MCF7 cells fail to infiltrate any scaffold, whereas highly invasive MDA-MB-231 cells display organ-specific invasion, preferentially penetrating lung and liver ECM while showing virtually no invasion of intestinal scaffolds, consistent with clinically observed metastatic tropism. Quantitative invasion rates closely match values reported in vivo by intravital microscopy. Overall, this ex vivo system provides an accessible and scalable platform to study ECM-driven determinants of metastatic invasion while reducing reliance on animal models.

The tumor microenvironment (TME), which is composed of various cell types and the extracellular matrix (ECM), plays crucial roles in cancer progression and treatment outcomes. However, the impact of the mechanical properties of the ECM, specifically collagen fibril alignment and crosslinking, on macrophage behavior and polarization is less understood. To investigate this, we reconstituted 3D collagen matrices to mimic the physical characteristics of the TME. Our results demonstrated that stiffening the matrix through the alignment or crosslinking of collagen fibrils promotes macrophage polarization toward the anti-inflammatory M2 phenotype. This phenotype is characterized by increased expression of CD105 and CD206 and a distinct cytokine secretion profile. The increased stiffness and aligned fibrils activate mechanotransduction pathways, notably integrin {beta}1 and PI3K signaling, leading to increased IL-4 secretion, which acts in an autocrine manner to further promote M2 polarization. Interestingly, these stiffened microenvironments also suppressed the proinflammatory response. In coculture experiments with breast cancer cell lines (MDA-MB-231 and MCF-7), macrophages within stiffened or aligned matrices significantly increased cancer cell proliferation and invasion. These findings suggest that the mechanical properties of the ECM, specifically its alignment and crosslinking, create a more favorable environment for tumor progression by modulating macrophage activity. Overall, our study underscores the critical role of ECM mechanics in shaping immune cell behavior within the TME, highlighting the potential for therapies that target ECM properties and macrophage polarization to inhibit cancer progression and enhance treatment efficacy.

Spiny mice (Acomys) can regenerate after injury with minimal fibrosis. Whether Acomys retains the fibrosis-free feature in response to implanted devices is unknown, so we implanted polydimethylsiloxane (PDMS) subcutaneously in Acomys and Mus, a non-regenerative counterpart. In Acomys, we found reduced myeloid cell infiltration, fibroblast activation, and collagen deposition around the PDMS implant. These results suggest that Acomys can regulate FBR and may hold the key to improving implant lifetime and functionality.

A wide range of conditions, including chronic inflammatory diseases and cancer, are characterized by the fibrotic microarchitecture and increased stiffness of collagen type I extracellular matrix. These conditions are typically accompanied by altered vascular function, including vessel leakiness, abnormal capillary morphology and stability. The dynamic cell-matrix interactions that regulate vascular function in healthy tissues have been well documented. However, our understanding of how the gradual mechanical and structural alterations in collagen type I affect vascular homeostasis remains elusive, especially as a function of the interactions between endothelial and perivascular cell with the altered matrix. Here we hypothesized that perivascular cells might function as mechano-structural sensors of the microvasculature by mediating the interaction between endothelial cells and altered collagen type I. To test that, we utilized an organotypic model of perivascular cell-supported vascular capillaries in collagen scaffolds of controlled microarchitecture and mechanics. Our results demonstrate that capillaries cultured in soft reticular collagen exhibited consistent pericyte differentiation, endothelial cell-cell junctions, and barrier function. In contrast, capillaries embedded in stiff and bundled collagen fibrils to mimic a more fibrotic matrix induced abluminal migration of perivascular cells, increased leakage, and marked expression of vascular remodeling and inflammatory markers. These patterns, however, were only observed when endothelial capillaries were engineered with perivascular cells. Silencing of NOTCH3, a mediator of endothelial-perivascular cell communication, largely re-established normal vascular morphology and function. In summary, our findings point to a novel mechanism of perivascular regulation of vascular dysfunction in fibrotic tissues which may have important implications for anti-angiogenic and anti-fibrotic therapies in cancer, chronic inflammatory diseases and regenerative medicine. Significance StatementThe fibrotic alterations in extracellular matrix structure and mechanics that are common to many chronic and inflammatory conditions are often associated with a decrease in vascular homeostasis. The mechanisms regulating these abnormalities remain poorly understood. Here, we demonstrate that perivascular cells play a critical role in sensing progressive microarchitectural and mechanical changes occurring in the ECM, drastically altering vascular capillary morphology and barrier function, and exacerbating the production of inflammatory and remodeling markers. These results point to a previously unknown mechano-structural sensory mechanisms mediated by perivascular cells in vascular capillaries that may help elucidate the progression of many profibrotic conditions, and point to possible new targets for antiangiogenic and antifibrotic therapies in cancer, chronic inflammatory conditions and regenerative medicine.

Peritoneal metastases (PM) from colorectal cancer (CRC) are associated with poor survival. The extracellular matrix (ECM) plays a fundamental role in modulating the homing of CRC metastases to the peritoneum. The mechanisms underlying the interactions between metastatic cells and the ECM, however, remain poorly understood and the number of in vitro models available for the study of the peritoneal metastatic process is limited. Here, we show that decellularized ECM of the peritoneal cavity allows the growth of organoids obtained from PM, favoring the development of three-dimensional nodules that maintain the characteristics of in vivo PM. Organoids preferentially grow on scaffolds obtained from neoplastic peritoneum, which are characterized by greater stiffness than normal scaffolds. A gene expression analysis of organoids grown on different substrates reflected faithfully the clinical and biological characteristics of the organoids. An impact of the ECM on the response to standard chemotherapy treatment for PM was also observed. SignificanceEvidence of the value of ex vivo 3D models obtained by combining patient-derived extracellular matrices depleted of cellular components and organoids to mimic the metastatic niche, to be used as a tool to develop new therapeutic strategies in a biologically relevant context, to personalize treatments and increase their efficacy.

Cellular therapy, such as beta cell transplantation for Type 1 diabetes, is a promising approach to durably alleviate disease states. Implanting cells within porous scaffolds is beneficial as they distribute the cells and mechanically support implantation; however, scaffolds can exacerbate foreign body responses (FBR). While the geometric features of a scaffold are known to impact FBR, there is limited consensus on what makes an ideal implant. Some have explored the role of pore size and interconnectivity; however, the impact of rung thickness between pores on FBR is broadly understudied. To investigate this parameter, we created a scaffold with reproducible geometric features and high biostability by combining 3D-printing with the polymer polydimethylsiloxane (PDMS). We tested 3D-printed scaffold prototypes with identical pore sizes but distinct PDMS rung thicknesses ranging from 150 to 300 {micro}m. Upon transplantation, biocompatibility screening in a mouse model revealed that scaffolds with thicker PDMS rungs led to increased intra-device fibrosis. Additional spatio-proteomic analysis revealed distinct differences in host responses to rung changes, with alterations in macrophage and adaptive immune cell markers, as well as fibrotic proteins, within scaffolds containing thicker rungs. Selecting the optimized rung size, we evaluated its efficacy in rat syngeneic and allogeneic islet transplant models. In the allogeneic model, 3D-printed scaffold islet implants demonstrated robust efficacy and stability, yielding improved outcomes compared to PDMS scaffolds without optimized geometric features. Results from this study reveal how specific geometric scaffold features critically influence FBR to biomaterial implants, accelerating or mitigating fibrotic responses, and ultimately determining transplant success.

Understanding the foreign-body response (FBR) of biomaterials is a prerequisite for the prediction of its clinical application, and the present assessments mainly rely on in vitro cell culture and in situ histopathology. However, remote organs responses after biomaterials implantation is unclear. Here, by leveraging body-wide-transcriptomics data, we performed in-depth systems analysis of biomaterials - remote organs crosstalk after abdominal implantation of polypropylene and silk fibroin using a rodent model, demonstrating local implantation caused remote organs responses dominated by acute-phase responses, immune system responses and lipid metabolism disorders. Of note, liver function was specially disturbed, defined as hepatic lipid deposition. Combining flow cytometry analyses and liver monocyte recruitment inhibition experiments, we proved that blood derived monocyte-derived Kupffer cells in the liver underlying the mechanism of abnormal lipid deposition induced by local biomaterials implantation. Moreover, from the perspective of temporality, the remote organs responses and liver lipid deposition of silk fibroin group faded away with biomaterial degradation and restored to normal at end, which highlighted its superiority of degradability. These findings were further indirectly evidenced by human blood biochemical examination from 141 clinical cases of hernia repair using silk fibroin mesh and polypropylene mesh. In conclusion, this study provided knowledge of biomaterials-body interactions. It is of great important for future development of biomaterial devices for clinical application. One Sentence SummaryAbdominal local biomaterials implantation induces remote organ fatty deposition through activated blood-derived Kupffer cells.

Altered mechanical properties of the tumor microenvironment (TME) influence cancer progression, yet the mechanistic basis by which 3D mechanics shape CAF heterogeneity and downstream tumor drug response remains poorly understood. Here, we engineered a modulus-tunable gelatin methacryloyl (GelMA) hydrogel platform spanning a normal-like (soft [~]2 kPa) to desmoplastic-like (stiff[~]40 kPa) range to culture primary breast CAFs under 3D confinement. CAFs exhibited pronounced volumetric morphoadaptation across matrices, with soft 3D matrices supporting larger, more protrusive morphologies and stiff gels constraining cell geometry. In contrast to canonical 2D paradigms, nuclear YAP localization was reduced in stiff 3D matrices and varied substantially across cells, consistent with a dominant role for 3D geometric/volumetric state in regulating mechanotransduction. Functionally, in transwell co-culture with MCF-7 spheroids under paclitaxel treatment, CAFs cultured in stiff 3D matrices induced a broader chemoresistance-associated transcriptional program, whereas soft 3D matrices CAFs favored stress/checkpoint-like responses. A 2D monolayer comparator indicated that coordinated resistance-associated programs emerge most clearly in 3D tumor architecture. Together, these results establish a GelMA-based biomaterials framework in which CAF volumetric state provides a quantifiable intermediate linking 3D matrix mechanics to mechanotransduction and tumor drug-response programs, motivating future strategies to modulate stromal function through mechanically controlled cell-state regulation.

T-cells navigate through various mechanical environments within the body, adapting their behavior in response to these cues. An altered extracellular matrix (ECM) characterized by increased density and enhanced fibril alignment, as observed in cancer tissues, can significantly impact essential T-cell functions critical for immune responses. In this study, we used 3D collagen matrices with controlled density and fibril alignment to investigate T-cell migration, activation, and proliferation. Our results revealed that dense and aligned collagen matrices suppress T-cell activation through enhanced YAP signaling. By inhibiting YAP signaling, we demonstrated that T-cell activation within these challenging microenvironments improved, suggesting potential strategies to enhance the efficacy of immunotherapy by modulating T-cell responses in dense and aligned ECMs. Overall, our study deepens our understanding of T-cell mechanobiology within 3D relevant cellular microenvironments and provides insights into countering ECM-induced T-cell immunosuppression in diseases such as cancer. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/585707v1_ufig1.gif" ALT="Figure 1"> View larger version (101K): org.highwire.dtl.DTLVardef@ccb840org.highwire.dtl.DTLVardef@5490eforg.highwire.dtl.DTLVardef@1f74d8borg.highwire.dtl.DTLVardef@103f739_HPS_FORMAT_FIGEXP M_FIG Dense and aligned extracellular matrices suppress T-cell activation via YAP signaling, affecting immunotherapy efficacy in diseases such as cancer. C_FIG

To treat acute myocardial infarction immediately after reperfusion, we previously engineered an intravascularly infusible decellularized extracellular matrix (iECM) biomaterial that exerts immunomodulatory and pro-reparative effects. However, the impact of the heterogeneous contents of iECM on infarct localization and downstream biological function is unknown. Using liquid chromatography, iECM is separated into a high molecular weight (MW) and low MW component. Mass spectrometry confirms compositional similarity, while biochemical assays and transmission electron microscopy highlight differences in biochemical features and structure, revealing a nanofibrillar high MW component and a globular peptide low MW. Quartz crystal microbalance studies show binding of each component to basal lamina ECM proteins and endothelial cell surface receptors under flow, demonstrating the specificity of ECM biomaterials to permeable vasculature. In vivo, the low MW component reduces vascular permeability, while neither component alone achieves the retention levels of complete iECM. Using single-nucleus RNA sequencing to probe bioactivity, both components elicited comparable angiogenic, immunomodulatory, and pro-reparative transcriptional programs. These findings illustrate that highly coupled materials and biological characterization uncover fundamental behaviors and properties of iECM biomaterials. Additionally, we show the unique binding behavior of iECM to the gaps of permeable vasculature, which could be exploited for future nanomaterial design.

The efficacy of cell-based therapeutics is often compromised by host immune recognition of implanted cells and biomaterials, resulting in fibrotic encapsulation and loss of function. Here, we address this challenge with an immunomodulatory cell-based therapy, in which alginate-encapsulated retinal pigment epithelial cells continuously secrete cytokines to locally modulate the implant microenvironment. In a healthy rodent model, the localized production of interleukin-10 (IL-10) or IL-12 from encapsulated cytokine-producing cells prevented host immune rejection and fibrosis of alginate capsules. Mechanistically, treatment was associated with reduced expression of pro-fibrotic genes and immune shifts consistent with macrophage and T-cell regulation, supporting a cytokine-mediated mitigation of foreign body response. In a diabetic murine model (streptozotocin-induced C57BL/6J), co-implantation of human islets with IL-10-producing cells attenuated pericapsular fibrosis, preserved islet viability, and restored normoglycemia for up to 100 days (4.76 times longer than islets alone). Significantly, IL-10-producing cells were also effective in enabling the durability and function of encapsulated cells in a healthy non-human primate, showing translational feasibility. Collectively, these findings suggest that localized cytokine delivery can reduce fibrotic encapsulation and support durable graft function, offering a path to lessen reliance on systemic immunosuppression in islets transplantation and other implantable biomaterial therapies. TeaserEncapsulated IL-10-producing cells locally suppress fibrosis and extend graft function in rodent models and a non-human primate.

Microvascular engineering seeks to exploit known cell-cell and cell-matrix interactions in the context of vasculogenesis to restore homeostatic or disease development of reliable capillary models in vitro. However, current systems generally focus on recapitulating microvessels embedded in thick gels of extracellular matrix, overlooking the significance of discontinuous capillaries, which play a vital role in tissue-blood exchanges particularly in organs like the liver. In this work, we introduce a novel method to stimulate the spontaneous organization of endothelial cells into non-embedded microvessels. By creating an anisotropic micropattern at the edge of a development-like matrix dome using Marangoni-flow, we achieved a long, non-random orientation of endothelial cells, laying a premise for stable lumenized microvessels. Our findings revealed a distinctive morphogenetic process leading to mature lumenized capillaries, demonstrated with both murine and human immortalized liver sinusoidal endothelial cell lines (LSECs). The progression of cell migration, proliferation and polarization was clearly guided by the pattern, initiating the formation of a multicellular cord that caused a deformation spanning extensive regions and generated a wave-like folding of the gel, hinged at a laminin depleted zone, enveloping the cord with gel proteins. This event marked the onset of lumenogenesis, regulated by the gradual apico-basal polarization of the wrapped cells, leading to the maturation of vessel tight junctions, matrix remodeling, and ultimately the formation of a lumen--recapitulating the development of vessels in vivo. Furthermore, we demonstrate that the process strongly relies on the initial gel edge topography, while the geometry of the vessels can be tuned, from a curved to a straight structure. We believe our facile engineering method, guiding an autonomous self-organization of vessels without the need for supporting cells or complex prefabricated scaffolds, holds promise for future integration into microphysiological systems featuring discontinuous, fenestrated capillaries. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/564881v2_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@1d6992org.highwire.dtl.DTLVardef@fe1434org.highwire.dtl.DTLVardef@e07d1aorg.highwire.dtl.DTLVardef@3540ab_HPS_FORMAT_FIGEXP M_FIG C_FIG

The shortage of donor organs for transplantation has prompted the development of alternative implantable human liver tissues; however, the need for a clinically viable liver tissue that can be fabricated using physiologically-relevant primary human hepatocytes (PHHs) is unmet. Purified silk proteins provide desirable features for generating implantable tissues, such as sustainable sourcing from insects/arachnids, biocompatibility, tunable mechanical properties and degradation rates, and low immunogenicity upon implantation; however, the utility of such scaffolds to generate human liver tissues using PHHs remains unclear. Here, we show that the incorporation of type I collagen during the fabrication and/or autoclaving of silk scaffolds was necessary to enable robust PHH attachment/function. Scaffolds with small pores (73 +/- 25 {micro}m) promoted higher PHH functions than large pores (235 +/- 84 {micro}m). Further incorporation of growth-arrested 3T3-J2 fibroblasts into scaffolds enhanced PHH functions up to 5-fold for 5 months in culture, an unprecedented longevity, and functions were better retained than 2D configurations. Lastly, encapsulating PHHs within Matrigel while housed in the silk/collagen scaffold led to higher functions than Matrigel or silk/collagen alone. In conclusion, porous silk scaffolds are useful for generating long-term PHH +/- fibroblast tissues which may ultimately find applications in regenerative medicine and drug development.

Proper placental vascularization is vital for pregnancy outcomes, but assessing it with animal models and human explants has limitations. Here, we present a 3D in vitro model of human placenta terminal villi that includes fetal mesenchyme and vascular endothelium. By co-culturing HUVEC, placental fibroblasts, and pericytes in a macro-fluidic chip with a flow reservoir, we generate fully perfusable fetal microvessels. Pressure-driven flow is crucial for the growth and remodeling of these microvessels, resulting in early formation of interconnected placental vascular networks and maintained viability. Computational fluid dynamics simulations predict shear forces, which increase microtissue stiffness, decrease diffusivity and enhance barrier function as shear stress rises. Mass-spec analysis reveals the deposition of numerous extracellular proteins, with flow notably enhancing the expression of matrix stability regulators, proteins associated with actin dynamics, and cytoskeleton organization. Our model provides a powerful tool for deducing complex in vivo parameters, such as shear stress on developing vascularized placental tissue, and holds promise for unraveling gestational disorders related to the vasculature.

Medical implants offer a unique and powerful therapeutic approach in many areas of medicine. However, their lifetime is often limited as they may cause a foreign body reaction (FBR) leading to their encapsulation by scar tissue1-4. Despite the importance of this process, how cells recognise implanted materials is still poorly understood5, 6. Here, we show how the mechanical mismatch between implants and host tissue leads to FBR. Fibroblasts and macrophages, which are both crucially involved in mediating FBR, became activated when cultured on materials just above the stiffness of healthy tissue. Coating stiff implants with a thin layer of hydrogel or silicone with a tissue-like elastic modulus ([~]20 kPa in subcutaneous and [~]2 kPa in peripheral nerve implants) or softer significantly reduced inflammation and fibrosis three months after implantation. Materials stiffer than the host tissue led to nuclear localisation of the mechanosensitive transcriptional regulator YAP in neighbouring cells in vivo, confirming mechanotransduction. The alleviation of FBR by soft coatings not exceeding the stiffness of the host tissue provides a strategy to achieve long-term implant stability without extensive modification of current implant manufacturing techniques, facilitating clinical translation.

Drug discovery for complex liver diseases faces alarming attrition rates. The lack of non-clinical models that recapitulate key aspects of liver (patho)-physiology is likely contributing to the inefficiency of developing effective treatments. Of particular notice is the common omission of an organized microvascular component despite its importance in maintaining liver function and its involvement in the development of several pathologies. Increasing the complexity of in vitro models is usually associated with a lack of scalability and robustness which hinders their implementation in drug development pipelines. Here, we describe a comprehensive liver MPS model comprising stellates, liver-derived endothelial cells and hepatocytes conceived within a scalable and automated platform. We show that endothelial cells self-organize in a microvascular network when co-cultured with stellates in a hydrogel. In a tri-culture, hepatocytes polarize accordingly, with a basolateral side facing blood vessels and an apical side facing bile-canaliculi-like structures. Stellates interact and surround the hollow microvessels. Steatosis was induced by exogenous administration of fatty acids which could be prevented by co-administration of firsocostat. Administration of TGF-{beta} resulted in an activated stellate cells phenotype which could be prevented by the co-administration of SB-431542. The model was implemented on a microtiter plate format comprising 64 chips which enabled the development of a fully automated, multiplexed fibrosis assay with a robust Z factor suitable for high-throughput applications.

Liver plays a vital role in the human immune system, in the internalization and catabolic clearance of therapeutic antibodies and antibody-bound immune complexes via Fc-receptor (FcR) binding on the hepatic reticuloendothelial system cells. This Fc portion of the antibody binding to FcR in the liver initiates the clearance of these antibodies or immune complexes, which is vital in the context of half-life, dosing interval, efficacy, and safety of therapeutic antibodies. The liver sinusoidal endothelial cells (LSECs) express scavenging receptors that recognize, bind, and internalize an enormous diversity of extracellular ligands. The Fc gamma receptor Fc{gamma}RIIB or CD32B on LSECs is responsible for the clearance of a large majority of IgG-bound immune complexes in the liver. Investigating the pharmacological effects of antibody clearance via human liver in vitro has been challenging due to the lack of reliable long-term LSEC culture protocols. Human LSECs downregulate the expression of CD32B rapidly in vitro in traditional 2D LSEC mono- and co-cultures. We describe a Liver-Chip model with a co-culture of primary human LSECs and hepatocytes to recreate the liver microenvironment and extend the viability and function of LSECs, including CD32B expression levels, for a duration that is relevant for assessing the pharmacokinetics (PK) of therapeutic antibodies. Our results show that the expression of CD32B can differ based on experimental variables such as the source of primary cells (donor), passage number or source of detection antibodies used to visualize CD32B and shear stress. The CD32B expression was maintained for 14 days on the Liver-Chip in a donor-dependent but passage number independent manner. The Scanning Electron Microscopy (SEM) imaging showed the presence of fenestrae structures - one of the hallmarks of LSEC function. Key LSEC markers, including CD32B expression, were validated through flow cytometry.

Fibrotic diseases are involved in 45% of deaths in the United States. In particular, fibrosis of the kidney and lung are major public health concerns due to their high prevalence and lack of existing treatment options. Here, we harness the pathophysiological features of fibrotic diseases, namely leaky vasculature and aberrant extracellular matrix (ECM) protein deposition (i.e. collagen), to target an anti-fibrotic biologic and a small molecule drug to disease sites of fibrosis, thus improving their therapeutic potential in mouse models of lung and kidney fibrosis. First, we identify and validate collagen-targeting drug delivery systems that preferentially accumulate in the diseased organs: von Willebrand Factors A3 domain (VWF-A3) and decorin-derived collagen-binding peptide-conjugated micelles (CBP-micelles). We then engineer and recombinantly express novel candidate biologic therapies based on the anti-inflammatory cytokine IL-10: A3-IL-10 and A3-Serum Albumin-IL-10 (A3-SA-IL-10). Simultaneously, we stably encapsulate the potential anti-fibrotic water-insoluble drug, rapamycin, in CBP-micelles. We show that these novel formulations of therapeutics bind to collagen in vitro and that their efficacy in mouse models of lung and kidney fibrosis is improved, compared to free, untargeted drugs. Our results demonstrate that collagen-targeted anti-fibrotic drugs may be next generation therapies of high clinical potential.

Organoid transplantation has a promising future in the treatment of liver disease, but a major limitation is the lack of guidance on the most appropriate method for transplantation that maximises organoid survival. Human induced pluripotent stem cell (hiPSC)-derived liver progenitor cell organoids were transplanted into four different transplantation sites in a mouse model of liver disease, using five organoid delivery methods. Organoids were transplanted into the vascularised chamber device established in the groin, or into the liver, spleen, and subcutaneous fat. For organoid transplantations into the liver, organoids were delivered either in Matrigel alone, or in Matrigel and a polyurethane scaffold. At 2 weeks post-transplantation, the vascularised chamber had the highest organoid survival, which was 5.1x higher than the site with second highest survival (p=0.0002), being the intra-hepatic scaffold approach. No organoid survival was observed when delivered into the liver without a scaffold, or when injected into the spleen. Very low survival occurred in transplantations into subcutaneous fat. Animals with the vascularised chamber also had the highest levels of human albumin (0.33 {+/-} 0.09 ng/mL). This study provides strong evidence supporting the use of the vascularised chamber for future liver organoid transplantation studies, including its translation into clinical therapy.

Non-degradable polymeric implantable medical devices are a mainstay of modern healthcare but can frequently lead to severe complications. These complications are largely attributable to the foreign body response (FBR), which is characterized by excessive inflammation and fibrosis in response to implanted materials. The pathologic mechanisms underpinning the FBR remain elusive; however, metabolism is increasingly regarded as a critical regulator of innate immune function. We conducted comprehensive metabolic profiling of implant-associated macrophages and multinucleated giant cells in response to the subcutaneous implantation of clinically relevant implantable materials in a mouse model of implant fibrosis. Leveraging novel metabolic characterization methods for analysis of both metabolic dependence and enzyme expression in heterogeneous peri-implant tissues, we demonstrate that peri-implant macrophages are glycolytic at least up to six weeks post-implantation. Glycolytically dependent peri-implant macrophages expression of glucose transporter 1 (GLUT1) increased temporally and with proximity to the implant-tissue interface. Paired rate-limiting metabolic enzyme expression analysis showed notable increases in biosynthetic pathways (G6PD and ACC1), matched with increased mitochondrial staining intensity in GLUT1Hi cells at chronic timepoints, which were not notable at early timepoints. Notably, we identified a glycolytic dependence of multinucleated macrophages associated with polymeric materials: these cells expressed higher levels of GLUT1 than mononuclear macrophages of comparable metabolic phenotype. Our findings highlight GLUT1-dependent glycolysis as the definitive metabolic system used by peri-implant macrophages and multinucleated cells in the FBR, highlighting this pathway as a potential target for the development of novel therapeutic approaches.