A micro-fragmented collagen gel as a cell-assembling platform for critical limb ischemia repair.

Critical limb ischemia (CLI) is a devastating disease characterized by the progressive blockage of blood vessels. Although the paracrine effect of growth factors in stem cell therapy made it a promising angiogenic therapy for CLI, poor cell survival in the harsh ischemic microenvironment limited its efficacy. Thus, an imperative need exists for a stem-cell delivery method that enhances cell survival. Here, a collagen microgel (CMG) cell-delivery scaffold (40 × 20 µm) was fabricated via micro-fragmentation from collagen-hyaluronic acid polyionic complex to improve transplantation efficiency. Culturing human adipose-derived stem cells (hASCs) with CMG enabled integrin receptors to interact with CMG to form injectable 3-dimensional constructs (CMG-hASCs) with a microporous microarchitecture and enhanced mass transfer. CMG-hASCs exhibited higher cell survival (p < 0.0001) and angiogenic potential in tube formation and aortic ring angiogenesis assays than cell aggregates. Injection of CMG-hASCs intramuscularly into CLI mice increased blood perfusion and limb salvage ratios by 40 % and 60 %, respectively, compared to cell aggregate-treated mice. Further immunofluorescent analysis revealed that transplanted CMG-hASCs have greater muscle regenerative and angiogenic potential, with enhanced cell survival than cell aggregates (p < 0.05). Collectively, we propose CMG as a cell-assembling platform and CMG-hASCs as promising therapeutics to treat CLI.

Artificial intelligence-driven new drug discovery targeting serine/threonine kinase 33 for cancer treatment.

BACKGROUND: Artificial intelligence (AI) is capable of integrating a large amount of related information to predict therapeutic relationships such as disease treatment with known drugs, gene expression, and drug-target binding. AI has gained increasing attention as a promising tool for next-generation drug development. METHODS: An AI method was used for drug repurposing and target identification for cancer. Among 8 survived candidates after background checking, N-(1-propyl-1H-1,3-benzodiazol-2-yl)-3-(pyrrolidine-1-sulfonyl) benzamide (Z29077885) was newly selected as an new anti-cancer drug, and the anti-cancer efficacy of Z29077885 was confirmed using cell viability, western blot, cell cycle, apoptosis assay in MDA-MB 231 and A549 in vitro. Then, anti-tumor efficacy of Z29077885 was validated in an in vivo A549 xenograft in BALB/c nude mice. RESULTS: First, we discovered an antiviral agent, Z29077885, as a new anticancer drug candidate using the AI deep learning method. Next, we demonstrated that Z29077885 inhibits Serine/threonine kinase 33 (STK33) enzymatic function in vitro and showed the anticancer efficacy in various cancer cells. Then, we found enhanced apoptosis via S-phase cell cycle arrest as the mechanism underlying the anticancer efficacy of Z29077885 in both lung and breast cancer cells. Finally, we confirmed the anti-tumor efficacy of Z29077885 in an in vivo A549 xenograft. CONCLUSIONS: In this study, we used an AI-driven screening strategy to find a novel anticancer medication targeting STK33 that triggers cancer cell apoptosis and cell cycle arrest at the s phase. It will pave a way to efficiently discover new anticancer drugs.

Effective protection of photoreceptors using an inflammation-responsive hydrogel to attenuate outer retinal degeneration.

Retinitis pigmentosa (RP) is an outer retinal degenerative disease that can lead to photoreceptor cell death and profound vision loss. Although effective regulation of intraretinal inflammation can slow down the progression of the disease, an efficient anti-inflammatory treatment strategy is still lacking. This study reports the fabrication of a hyaluronic acid-based inflammation-responsive hydrogel (IRH) and its epigenetic regulation effects on retinal degeneration. The injectable IRH was designed to respond to cathepsin overexpression in an inflammatory environment. The epigenetic drug, the enhancer of zeste homolog 2 (EZH2) inhibitors, was loaded into the hydrogel to attenuate inflammatory factors. On-demand anti-inflammatory effects of microglia cells via the drug-loaded IRH were verified in vitro and in vivo retinal degeneration 10 (rd10) mice model. Therefore, our IRH not only reduced intraretinal inflammation but also protected photoreceptors morphologically and functionally. Our results suggest the IRH reported here can be used to considerably delay vision loss caused by RP.

Eye-Mimicked Neural Network Composed of Photosensitive Neural Spheroids with Human Opsin Proteins.

An in vitro model, composed of the short-wavelength human opsins and rhodopsins, is created. Two types of photosensitive neural spheroids are transfected for selective reaction under bluish-purple and green lights. These are employed to two devices with intact neuron and neural-spheroid to study the interaction. By photostimulation, the photosensitive spheroid initiated photoactivation, and the signal generated from its body is transmitted to adjacent neural networks. Specifically, the signal traveled through the axon bundle in narrow gap from photosensitive spheroid to intact spheroid as an eye-to-brain model including optic nerve. The whole process with photosensitive spheroid is monitored by calcium ion detecting fluorescence images. The results of this study can be applied to examine vision restoration and novel photosensitive biological systems with spectral sensitivity.

Functionally enhanced cell spheroids for stem cell therapy: Role of TIMP1 in the survival and therapeutic effectiveness of stem cell spheroids.

Stem cell therapy has emerged as a promising regenerative medicine strategy but is limited by poor cell survival, leading to low therapeutic outcomes. We developed cell spheroid therapeutics to overcome this limitation. We utilized solid-phase FGF2 to form functionally enhanced cell spheroid-adipose derived (FECS-Ad), a type of cell spheroid that preconditions cells with intrinsic hypoxia to increase the survival of transplanted cells. We demonstrated an increase in hypoxia-inducible factor 1-alpha (HIF-1α) levels in FECS-Ad, which led to the upregulation of tissue inhibitor of metalloproteinase 1 (TIMP1). TIMP1 enhanced the survival of FECS-Ad, presumably through the CD63/FAK/Akt/Bcl2 anti-apoptotic signaling pathway. Cell viability of transplanted FECS-Ad was reduced by TIMP1 knockdown in an in vitro collagen gel block and a mouse model of critical limb ischemia (CLI). TIMP1 knockdown in FECS-Ad inhibited angiogenesis and muscle regeneration induced by FECS-Ad transplanted into ischemic mouse tissue. Genetic overexpression of TIMP1 in FECS-Ad further promoted the survival and therapeutic efficacy of transplanted FECS-Ad. Collectively, we suggest that TIMP1 acts as a key survival factor to improve the survival of transplanted stem cell spheroids, which provides scientific evidence for enhanced therapeutic efficacy of stem cell spheroids, and FECS-Ad as a potential therapeutic agent to treat CLI. STATEMENT OF SIGNIFICANCE: We used FGF2-tethered substrate platform to form adipose-derived stem cell spheroids, as we named as functionally enhanced cell spheroid-adipose derived (FECS-Ad). In this paper, we showed that intrinsic hypoxia of spheroids upregulated expression of HIF-1α, which in turn upregulated expression of TIMP1. Our paper highlights TIMP1 as a key survival factor to improve survival of transplanted stem cell spheroids. We believe that our study has a very strong scientific impact as extending transplantation efficiency is essential for successful stem cell therapy.

Hydrogel/Nanofiber Composite Wound Dressing Optimized for Skin Layer Regeneration through the Mechanotransduction-Based Microcellular Environment.

Wound dressings have been designed to provide the optimal environment to fibroblasts, keratinocytes, and macrophages to promote wound healing while inhibiting potential microbial infection. Gelatin methacrylate (GelMA) is a photopolymerizable hydrogel with a gelatin backbone that contains natural cell binding motifs such as arginine-glycine-aspartic acid (RGD) and MMP-sensitive degradation sites, making it an ideal material for wound dressing. However, GelMA alone is unable to stably protect the wound and regulate cellular activities due to its weak mechanical properties and nonmicropatterned surface, limiting its application as a wound dressing. Herein, we report the development of a hydrogel-nanofiber composite wound dressing utilizing GelMA and poly(caprolactone) (PCL)/gelatin nanofiber, which can systematically manage the skin regeneration process with an enhanced mechanical property and micropatterned surface. GelMA sandwiched between electrospun aligned and interlaced nanofibers that mimic epidermis and dermis layers, respectively, increased the stiffness of the resulting hydrogel composite with a comparable swelling rate as GelMA. Fabricated hydrogel composite was determined to be biocompatible and nontoxic. In addition to the beneficial effect of GelMA in accelerating wound healing, subsequent histological analysis revealed upregulated re-epithelialization of granulation tissue and deposition of mature collagen. Hydrogel composite interacted with fibroblasts to regulate their morphology, proliferation, and collagen synthesis, as well as the expression of α-SMA, TGF-ß, and collagen I and III during the wound healing process both in vitro and in vivo. Taken together, we propose hydrogel/nanofiber composite as a wound dressing of the next generation that can induce skin tissue layer regeneration beyond the basic wound closure promotion of present dressings.

Facile construction of tumour spheroids with induced M2 macrophage polarization for anticancer drug screening.

Tumour-associated macrophages (TAMs) are involved in cancer progression and drug resistance in the tumour microenvironment (TME). Consequently, macrophages as therapeutic targets have garnered increased attention; however, there are hurdles to screening interactions between cancer and macrophages owing to technical difficulties in recapitulatingin vitrophysiological systems. In this study, we propose a simple strategy to construct tumour spheroids with induced M2 macrophage polarization for anticancer drug screening. We observed that cytokine expression related to the TME in three-dimensional (3D) cancer spheroids was enhanced compared with that in two-dimensional conventional cancer cell cultures. We also demonstrated that the 3D breast tumour spheroids promote M2-like TAM polarization via granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor. Furthermore, adipose tissue-derived stem cells, an abundant stromal cell population in the breast cancer TME, further enhanced the M2 phenotype in thein vitrotumour spheroids. Therefore, we propose the tumour spheroids as a drug screening platform to evaluate drug efficacy in cancers. Overall, the simple strategy to form tumour spheroids developed in this study will broaden the understanding of communication between cancer cells and macrophages and contribute to the evaluation of cancers and the development of better strategies for their therapy and management.

Fibroblasts Close a Void in Free Space by a Purse-String Mechanism.

The mechanism by which stromal cells fill voids in injured tissue remains a fundamental question in regenerative medicine. While it is well-established that fibroblasts fill voids by depositing extracellular matrix (ECM) proteins as they migrate toward the wound site, little is known about their ability to adopt an epithelial-like purse-string behavior. To investigate fibroblast behavior during gap closure, we created an artificial wound with a large void space. We discovered that fibroblasts could form a free-standing bridge over deep microvoids, closing the void via purse-string contraction, a mechanism previously thought to be unique to epithelial wound closure. The findings also revealed that myosin II mediated contractility and intercellular adherent junctions were required for the closure of the fibroblast gap in our fabricated three-dimensional artificial wound. To fulfill their repair function under the specific microenvironmental conditions of wounds, fibroblasts appeared to acquire the structural features of epithelial cells, namely, contractile actin bundles that span over multiple cells along the boundary. These findings shed light on a novel mechanism by which stromal cells bridge the 3D gap during physiological processes such as morphogenesis and wound healing.

TIMP-1-expressing breast tumor spheroids for the evaluation of drug penetration and efficacy.

Abundance of stromal cells and extracellular matrix (ECM) is observed in breast cancer, acting as a barrier for drug penetration and presenting a key issue for developing efficient therapeutics. In this study, we aimed to develop a three-dimensional (3D) multicellular tumor model comprising cancer and stromal cells that could effectively mimic the drug resistance properties of breast cancer. Three different types of spheroid models were designed by co-culturing breast cancer cells (MDA-MB-231) with three different types of stromal cells: human adipose-derived stromal cells (hASCs), human bone marrow stromal cells, or human dermal fibroblasts. Compared with other models, in the hASC co-culture model, tissue inhibitor of metalloproteinases-1 (TIMP-1) was highly expressed and the activity of matrix metalloproteinases was decreased, resulting in a higher ECM deposition on the spheroid surfaces. This spheroid model showed less drug penetration and treatment efficacy than the other models. TIMP-1 silencing in hASCs reduced ECM protein expression and increased drug penetration and vulnerability. A quantitative structure-activity relationship study using multiple linear regression drew linear relationships between the chemical properties of drugs and experimentally determined permeability values. Drugs that did not match the drug-likeness rules exhibited lower permeability in the 3D tumor model. Taken together, our findings indicate that this 3D multicellular tumor model may be used as a reliable platform for efficiently screening therapeutics agents for solid tumors.

Cytosolic microRNA-inducible nuclear translocation of Cas9 protein for disease-specific genome modification.

MicroRNA-dependent mRNA decay plays an important role in gene silencing by facilitating posttranscriptional and translational repression. Inspired by this intrinsic nature of microRNA-mediated mRNA cleavage, here, we describe a microRNA-targeting mRNA as a switch platform called mRNA bridge mimetics to regulate the translocation of proteins. We applied the mRNA bridge mimetics platform to Cas9 protein to confer it the ability to translocate into the nucleus via cleavage of the nuclear export signal. This system performed programmed gene editing in vitro and in vivo. Combinatorial treatment with cisplatin and miR-21-EZH2 axis-targeting CRISPR Self Check-In improved sensitivity to chemotherapeutic drugs in vivo. Using the endogenous microRNA-mediated mRNA decay mechanism, our platform is able to remodel a cell's natural biology to allow the entry of precise drugs into the nucleus, devoid of non-specific translocation. The mRNA bridge mimetics strategy is promising for applications in which the reaction must be controlled via intracellular stimuli and modulates Cas9 proteins to ensure safe genome modification in diseased conditions.

On-Demand Local Immunomodulation via Epigenetic Control of Macrophages Using an Inflammation-Responsive Hydrogel for Accelerated Wound Healing.

Effective resolution of inflammation contributes to favorable tissue regenerative therapeutic outcomes. However, fine coordination of local immunomodulation in a timely manner is limited because of the lack of strategies for controlling disease dynamics. We developed an inflammation-responsive hydrogel (IFRep gel) as an effective therapeutic strategy for on-demand epigenetic modulation against disease dynamics in wound healing. The IFRep gel is designed to control drug release by cathepsins according to the state of inflammation for active disease treatment. The gel loaded with an inhibitor of the epigenetic reader bromodomain (BRD)4 regulates the translocation of nuclear factor erythroid 2 to the nucleus, where it promotes antioxidant gene expression to reverse the inflammatory macrophage state in vitro. In addition, on-demand BRD inhibition using the responsive hydrogel accelerates wound healing by controlling the early inflammatory phase and keratinocyte activation in vivo. Our data demonstrate the clinical utility of using the IFRep gel as a promising strategy for improving therapeutic outcomes in inflammation-associated diseases.

Acetate decreases PVR/CD155 expression via PI3K/AKT pathway in cancer cells.

In recent years, restoring anti-tumor immunity has garnered a growing interest in cancer treatment. As potential therapeutics, immune checkpoint inhibitors have demonstrated benefits in many clinical studies. Although various methods have been applied to suppress immune checkpoints to boost anti-tumor immunity, including the use of immune checkpoint inhibitors, there are still unmet clinical needs to improve the response rate of cancer treatment. Here, we show that acetate can suppress the expression of poliovirus receptor (PVR/CD155), a ligand for immune checkpoint, in colon cancer cells. We demonstrated that acetate treatment could enhance effector responses of CD8+ T cells by decreasing the expression of PVR/CD155 in cancer cells. We also found that acetate could reduce the expression of PVR/CD155 by deactivating the PI3K/AKT pathway. These results demonstrate that acetate-mediated expression of PVR/ CD155 in cancer cells might potentiate the anti-tumor immunity in the microenvironment of cancer. Our findings indicate that maintaining particular acetate concentrations could be a complementary strategy in current cancer treatment. [BMB Reports 2021; 54(8): 431-436].

FGF2-primed 3D spheroids producing IL-8 promote therapeutic angiogenesis in murine hindlimb ischemia.

Peripheral artery disease is a progressive, devastating disease that leads to critical limb ischemia (CLI). Therapeutic angiogenesis using stem cell therapy has emerged as a promising approach for its treatment; however, adapting cell-based therapy has been limited by poor cell survival and low treatment efficiency. To overcome unmet clinical needs, we developed a fibroblast growth factor 2 (FGF2)-immobilized matrix that enabled control of cell adhesion to the surface and exerted a priming effect on the cell. Human adipose-derived stem cells (hASCs) grown in this matrix formed a functionally enhanced cells spheroid (FECS-Ad) that secreted various angiogenic factors including interleukin-8 (IL-8). We demonstrated that IL-8 was upregulated by the FGF2-mediated priming effect during FECS-Ad formation. Immobilized FGF2 substrate induced stronger IL-8 expression than soluble FGF2 ligands, presumably through the FGFR1/JNK/NF-κB signaling cascade. In IL-8-silenced FECS-Ad, vascular endothelial growth factor (VEGF) expression was decreased and angiogenic potential was reduced. Intramuscular injection of FECS-Ad promoted angiogenesis and muscle regeneration in mouse ischemic tissue, while IL-8 silencing in FECS-Ad inhibited these effects. Taken together, our data demonstrate that IL-8 contributes to therapeutic angiogenesis and suggest that FECS-Ad generated using the MBP-FGF2 matrix might provide a reliable platform for developing therapeutic agents to treat CLI.

Exosomal miRNA-19a and miRNA-614 Induced by Air Pollutants Promote Proinflammatory M1 Macrophage Polarization via Regulation of RORα Expression in Human Respiratory Mucosal Microenvironment.

Air pollution exposure leads to various inflammatory diseases in the human respiratory system. Chronic rhinosinusitis is an inflammatory disease caused by viruses, bacteria, or air pollutants. However, the underlying molecular mechanisms through which air particulate matter (PM) causes inflammation and disease remain unclear. In this article, we report that the induction of exosomal microRNAs (miRNAs) from human nasal epithelial cells upon airborne PM exposure promotes proinflammatory M1 macrophage polarization via downregulated RORα expression. Exposure of human nasal epithelial cells to PM results in inflammation-related miRNA expression, and more miRNA is secreted through exosomes delivered to macrophages. Among these, miRNA-19a and miRNA-614 directly bind to the 3'-untranslated region of RORα mRNA and downregulate RORα expression, which leads to inflammation due to inflammatory cytokine upregulation and induces macrophages to a proinflammatory M1-like state. Finally, we showed enhanced expression of miRNA-19a and miRNA-614 but reduced RORα expression in a chronic rhinosinusitis patient tissue compared with the normal. Altogether, our results suggest that PM-induced exosomal miRNAs might play a crucial role in the proinflammatory mucosal microenvironment and macrophage polarization through the regulation of RORα expression.

Combinatorial Inhibition of Cell Surface Receptors Using Dual Aptamer-Functionalized Nanoconstructs for Cancer Treatment.

Membrane receptors overexpressed in diseased states are considered novel therapeutic targets. However, the single targeting approach faces several fundamental issues, such as poor efficacy, resistance, and toxicity. Here, we report a dual-targeting strategy to enhance anti-cancer efficacy via synergistic proximity interactions between therapeutics and two receptor proteins. Importantly, we report the first finding of an interaction between c-Met and nucleolin and demonstrate the therapeutic value of targeting the interaction between them. Bispecific nanocarriers densely grafted with anti-c-Met and -nucleolin aptamer increased the local concentration of aptamers at the target sites, in addition to inducing target receptor clustering. It was also demonstrated that the simultaneous targeting of c-Met and nucleolin inhibited the cellular functions of the receptors and increased anti-cancer efficacy by altering the cell cycle. Our findings pave the way for the development of an effective combinatorial treatment based on nanoconstruct-mediated interaction between receptors.

Self-Organized Liver Microtissue on a Bio-Functional Surface: The Role of Human Adipose-Derived Stromal Cells in Hepatic Function.

The maintenance of hepatocyte function is a critical research topic in liver tissue engineering. Although an increasing number of strategies have been developed, liver tissue engineering using hepatocytes as a therapeutic alternative remains challenging owing to its poor efficacy. In this study, we developed a multicellular hepatic microtissue to enhance the function of induced hepatic precursor cells. Mouse induced hepatic precursor cells (miHeps) were self-organized in 3D with human adipose-derived stem cells (hASCs) on a bio-functional matrix. We found that hepatic phenotypes, such as levels of albumin, asialoglycoprotein receptor-1, and cytochrome P450, were enhanced in miHeps-hASC microtissue comprising miHeps and hASCs relative to two-dimensional-cultured miHeps-hASCs. Additionally, the secretome of 3D-cultured hASCs increased the hepatic function of mature miHeps. Furthermore, hepatic gene expression was reduced in mature miHeps treated with conditioned media of hypoxia-inducible factor 1α (HIF1α)-depleted hASCs relative to that with conditioned media of control hASCs. Our results suggested that the hepatic function of 3D-co-cultured miHeps could be enhanced by HIF1α-dependent factors secreted from stromal cells. This study provides an insight into the factors regulating hepatic function and shows that self-organized hepatic microtissue could act as liver spheroids for liver regenerative medicine and liver toxicity tests.

RORα Regulates Cholesterol Metabolism of CD8+ T Cells for Anticancer Immunity.

Retinoic acid-related orphan receptor α (RORα) functions as a transcription factor for various biological processes, including circadian rhythm, inflammation, cancer, and lipid metabolism. Here, we demonstrate that RORα is crucial for maintaining cholesterol homeostasis in CD8+ T cells by attenuating NF-kB transcriptional activity. Cholesterol sulfate, the established natural agonist of RORα, exhibits cellular cytotoxicity on, and increased effector responses in, CD8+ T cells. Transcript analysis reveals that the suppression of RORα leads to the upregulation of NF-kB target genes in T cells. Chromatin immunoprecipitation analysis was used to determine the corecruitment of RORα and histone deacetylase (HDAC) on NF-kB target promoters and the subsequent dismissal of coactivators for transcriptional repression. We demonstrate that RORα/HDAC-mediated attenuation of NF-kB signaling controls the balance of cholesterol metabolism in CD8+ T cells, and that therapeutic strategies targeting this epigenetic regulation could be beneficial to the treatment of solid tumors including colon cancers.

Machine learning-based design strategy for 3D printable bioink: elastic modulus and yield stress determine printability.

Although three-dimensional (3D) bioprinting technology is rapidly developing, the design strategies for biocompatible 3D-printable bioinks remain a challenge. In this study, we developed a machine learning-based method to design 3D-printable bioink using a model system with naturally derived biomaterials. First, we demonstrated that atelocollagen (AC) has desirable physical properties for printing compared to native collagen (NC). AC gel exhibited weakly elastic and temperature-responsive reversible behavior forming a soft cream-like structure with low yield stress, whereas NC gel showed highly crosslinked and temperature-responsive irreversible behavior resulting in brittleness and high yield stress. Next, we discovered a universal relationship between the mechanical properties of ink and printability that is supported by machine learning: a high elastic modulus improves shape fidelity and extrusion is possible below the critical yield stress; this is supported by machine learning. Based on this relationship, we derived various formulations of naturally derived bioinks that provide high shape fidelity using multiple regression analysis. Finally, we produced a 3D construct of a cell-laden hydrogel with a framework of high shape fidelity bioink, confirming that cells are highly viable and proliferative in the 3D constructs.

Fabrication of 3D plotted scaffold with microporous strands for bone tissue engineering.

Scaffold porosity has played a key role in bone tissue engineering aimed at effective tissue regeneration, by promoting cell attachment, proliferation, and osteogenic differentiation for new bone formation. Three-dimensional plotting systems (3DPSs) have been widely used to introduce porosity to the scaffold; however, introducing certain features in the scaffold strands that improve bone tissue regeneration remains a challenge. In this work, we fabricated bone tissue scaffolds with macro- and microporous structural features using a 3DPS and non-solvent-induced phase separation method. This approach allowed both macro- and micropores to be created in the scaffold strands. The surface morphology and mechanical and degradation properties of the perforated scaffolds were characterized carefully. Human marrow stromal cells were cultured on the scaffolds and then analyzed in vitro to assess scaffold bio-function. The highly porous scaffold exhibited mechanical properties similar to those of cancellous bone. Cell attachment, proliferation, and differentiation were significantly higher in porous scaffold compared to its nonporous counterpart. These results suggest that highly porous scaffolds have tremendous potential as a bone tissue regeneration platform.

Identification of urban particulate matter-induced disruption of human respiratory mucosa integrity using whole transcriptome analysis and organ-on-a chip.

BACKGROUND: Exposure to air particulate matter (PM) is associated with various diseases in the human respiratory system. To date, most in vitro studies showing cellular responses to PM have been performed in cell culture using a single cell type. There are few studies considering how multicellular networks communicate in a tissue microenvironment when responding to the presence of PM. Here, an in vitro three-dimensional (3D) respiratory mucosa-on-a-chip, composed of human nasal epithelial cells, fibroblasts, and endothelial cells, is used to recapitulate and better understand the effects of urban particulate matter (UPM) on human respiratory mucosa. RESULTS: We hypothesized that the first cells to contact with UPM, the nasal epithelial cells, would respond similar to the tissue microenvironment, and the 3D respiratory mucosa model would be a suitable platform to capture these events. First, whole transcriptome analysis revealed that UPM induced gene expression alterations in inflammatory and adhesion-related genes in human nasal epithelial cells. Next, we developed an in vitro 3D respiratory mucosa model composed of human nasal epithelial cells, fibroblasts, and endothelial cells and demonstrated that the model is structurally and functionally compatible with the respiratory mucosa. Finally, we used our model to expose human nasal epithelial cells to UPM, which led to a disruption in the integrity of the respiratory mucosa by decreasing the expression of zonula occludens-1 in both the epithelium and endothelium, while also reducing vascular endothelial cadherin expression in the endothelium. CONCLUSIONS: We demonstrate the potential of the 3D respiratory mucosa model as a valuable tool for the simultaneous evaluation of multicellular responses caused by external stimuli in the human respiratory mucosa. We believe that the evaluation strategy proposed in the study will move us toward a better understanding of the detailed molecular mechanisms associated with pathological changes in the human respiratory system.