The Conventional and Breakthrough Tool for the Study of L-Glutamate Transporters.

In our recent report, we clarified the direct interaction between the excitatory amino acid transporter (EAAT) 1/2 and polyunsaturated fatty acids (PUFAs) by applying electrophysiological and molecular biological techniques to Xenopus oocytes. Xenopus oocytes have a long history of use in the scientific field, but they are still attractive experimental systems for neuropharmacological studies. We will therefore summarize the pharmacological significance, advantages (especially in the study of EAAT2), and experimental techniques that can be applied to Xenopus oocytes; our new findings concerning L-glutamate (L-Glu) transporters and PUFAs; and the significant outcomes of our data. The data obtained from electrophysiological and molecular biological studies of Xenopus oocytes have provided us with further important questions, such as whether or not some PUFAs can modulate EAATs as allosteric modulators and to what extent docosahexaenoic acid (DHA) affects neurotransmission and thereby affects brain functions. Xenopus oocytes have great advantages in the studies about the interactions between molecules and functional proteins, especially in the case when the expression levels of the proteins are small in cell culture systems without transfections. These are also proper to study the mechanisms underlying the interactions. Based on the data collected in Xenopus oocyte experiments, we can proceed to the next step, i.e., the physiological roles of the compounds and their significances. In the case of EAAT2, the effects on the neurotransmission should be examined by electrophysiological approach using acute brain slices. For new drug development, pharmacokinetics pharmacodynamics (PKPD) data and blood brain barrier (BBB) penetration data are also necessary. In order not to miss the promising candidate compounds at the primary stages of drug development, we should reconsider using Xenopus oocytes in the early phase of drug development.

Overcoming antibody-resistant SARS-CoV-2 variants with bispecific antibodies constructed using non-neutralizing antibodies.

A current challenge is the emergence of SARS-CoV-2 variants, such as BQ.1.1 and XBB.1.5, that can evade immune defenses, thereby limiting antibody drug effectiveness. Emergency-use antibody drugs, including the widely effective bebtelovimab, are losing their benefits. One potential approach to address this issue are bispecific antibodies which combine the targeting abilities of two antibodies with distinct epitopes. We engineered neutralizing bispecific antibodies in the IgG-scFv format from two initially non-neutralizing antibodies, CvMab-6 (which binds to the receptor-binding domain [RBD]) and CvMab-62 (targeting a spike protein S2 subunit epitope adjacent to the known anti-S2 antibody epitope). Furthermore, we created a bispecific antibody by incorporating the scFv of bebtelovimab with our anti-S2 antibody, demonstrating significant restoration of effectiveness against bebtelovimab-resistant BQ.1.1 variants. This study highlights the potential of neutralizing bispecific antibodies, which combine existing less effective anti-RBD antibodies with anti-S2 antibodies, to revive the effectiveness of antibody therapeutics compromised by immune-evading variants.

Stress granule-mediated RNA regulatory mechanism in Alzheimer's disease.

Living organisms experience a range of stresses. To cope effectively with these stresses, eukaryotic cells have evolved a sophisticated mechanism involving the formation of stress granules (SGs), which play a crucial role in protecting various types of RNA species under stress, such as mRNAs and long non-coding RNAs (lncRNAs). SGs are non-membranous cytoplasmic ribonucleoprotein (RNP) granules, and the RNAs they contain are translationally stalled. Importantly, SGs have been thought to contribute to the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD). SGs also contain multiple RNA-binding proteins (RBPs), several of which have been implicated in AD progression. SGs are transient structures that dissipate after stress relief. However, the chronic stresses associated with aging lead to the persistent formation of SGs and subsequently to solid-like pathological SGs, which could impair cellular RNA metabolism and also act as a nidus for the aberrant aggregation of AD-associated proteins. In this paper, we provide a comprehensive summary of the physical basis of SG-enriched RNAs and SG-resident RBPs. We then review the characteristics of AD-associated gene transcripts and their similarity to the SG-enriched RNAs. Furthermore, we summarize and discuss the functional implications of SGs in neuronal RNA metabolism and the aberrant aggregation of AD-associated proteins mediated by SG-resident RBPs in the context of AD pathogenesis. Geriatr Gerontol Int 2024; 24: 7-14.

Visualization of small brain nuclei with a high-spatial resolution, clinically available whole-body PET scanner.

OBJECTIVE: To verify the visibility of physiological 18F-fluorodeoxyglucose (18F-FDG) uptake in nuclei in and around the brainstem by a whole-body (WB) silicon photomultiplier positron emission tomography (SiPM-PET) scanner with point-spread function (PSF) reconstruction using various iteration numbers. METHODS: Ten healthy subjects (5 men, 5 women; mean age, 56.0 ± 5.0 years) who underwent 18F-FDG PET/CT using a WB SiPM-PET scanner and magnetic resonance imaging (MRI) of the brain including a spin-echo three-dimensional sampling perfection with application-optimized contrasts using different flip angle evolutions fluid-attenuated inversion recovery (3D-FLAIR) and a 3D-T1 magnetization-prepared rapid gradient-echo (T1-MPRAGE) images were enrolled. Each acquired PET image was reconstructed using ordered-subset expectation maximization (OSEM) with iteration numbers of 4, 16, 64, and 256 (subset 5 fixed) + time-of-flight (TOF) + PSF. The reconstructed PET images and 3D-FLAIR images for each subject were registered to individual T1-MPRAGE volumes using normalized mutual information criteria. For each MR-coregistered individual PET image, the pattern of FDG uptake in the inferior olivary nuclei (ION), dentate nuclei (DN), midbrain raphe nuclei (MRN), inferior colliculi (IC), mammillary bodies (MB), red nuclei (RN), subthalamic nuclei (STN), lateral geniculate nuclei (LGN), medial geniculate nuclei (MGN), and superior colliculi (SC) was visually classified into the following three categories: good, clearly distinguishable FDG accumulation; fair, obscure contour of FDG accumulation; poor, FDG accumulation indistinguishable from surrounding uptake. RESULTS: Among individual 18F-FDG PET images with OSEM iterations of 4, 16, 64, and 256 + TOF + PSF, the iteration numbers that showed the best visibility in each structure were as follows: ION, MRN, LGN, MGN, and SC, iteration 64; DN, iteration 16; IC, iterations 16, 64, and 256; MB, iterations 64 and 256; and RN and STN, iterations 16 and 64, respectively. Of the four iterations, the 18F-FDG PET image of iteration 64 visualized FDG accumulation in small structures in and around the brainstem most clearly (good, 98 structures; fair, 2 structures). CONCLUSIONS: A clinically available WB SiPM-PET scanner is useful for visualizing physiological FDG uptake in small brain nuclei, using a sufficiently high number of iterations for OSEM with TOF and PSF reconstructions.

Association of sarcopenia defined by different skeletal muscle mass measurements with prognosis and quality of life in older patients with heart failure.

BACKGROUND: Diagnosing sarcopenia in heart failure (HF) patients is important, but how to assess skeletal muscle mass in HF patients with fluid retention is controversial. We aimed to examine the association between sarcopenia, defined by different skeletal muscle mass measurements, and clinical outcomes in older HF patients. METHODS: We included 546 older HF patients (≥ 65 years) who were assessed for sarcopenia at discharge (median age 77 years, 309 males). Sarcopenia was diagnosed using grip strength, usual gait speed, and skeletal muscle mass according to international criteria. We used mid-upper arm circumference (MUAC), mid-upper arm muscle circumference (MAMC), calf circumference (CC), and skeletal muscle mass index (SMI) assessed by bioelectrical impedance analysis to assess skeletal muscle mass and defined sarcopenia in each of these measurements. Prognostic outcomes were composite events (all-cause death and HF rehospitalization) and cardiovascular disease (CVD) events (CVD death and CVD rehospitalization). Quality of life (QOL) was assessed using the 36-item Short-Form Health Survey physical functioning (SF-36PF) score. RESULTS: The sarcopenia defined by MUAC [hazard ratio (HR): 2.50; 95 % confidence interval (95 % CI): 1.64-3.81; p < 0.001] or MAMC (HR: 1.98; 95 % CI: 1.35-2.92; p = 0.001) were associated with higher composite event rates than the non-sarcopenia. The sarcopenia defined by MUAC (HR: 1.88; 95 % CI: 1.25-2.83; p = 0.002) or MAMC (HR: 1.70; 95 % CI: 1.16-2.49; p = 0.007) were associated with higher CVD event rates than the non-sarcopenia. The sarcopenia defined by CC or SMI were not associated with prognoses. The sarcopenia defined by MUAC, MAMC, or CC were associated with low SF-36PF scores (all p < 0.05). CONCLUSIONS: These results suggest that a diagnosis of sarcopenia based on MUAC or MAMC rather than CC or SMI reflects prognosis and QOL in older HF patients.

Neuroprotective Potential of L-Glutamate Transporters in Human Induced Pluripotent Stem Cell-Derived Neural Cells against Excitotoxicity.

Human induced pluripotent stem cell (hiPSC)-derived neural cells have started to be used in safety/toxicity tests at the preclinical stage of drug development. As previously reported, hiPSC-derived neurons exhibit greater tolerance to excitotoxicity than those of primary cultures of rodent neurons; however, the underlying mechanisms remain unknown. We here investigated the functions of L-glutamate (L-Glu) transporters, the most important machinery to maintain low extracellular L-Glu concentrations, in hiPSC-derived neural cells. We also clarified the contribution of respective L-Glu transporter subtypes. At 63 days in vitro (DIV), we detected neuronal circuit functions in hiPSC-derived neural cells by a microelectrode array system (MEA). At 63 DIV, exposure to 100 µM L-Glu for 24 h did not affect the viability of neural cells. 100 µM L-Glu in the medium decreased to almost 0 µM in 60 min. Pharmacological inhibition of excitatory amino acid transporter 1 (EAAT1) and EAAT2 suppressed almost 100% of L-Glu decrease. In the presence of this inhibitor, 100 µM L-Glu dramatically decreased cell viability. These results suggest that in hiPSC-derived neural cells, EAAT1 and EAAT2 are the predominant L-Glu transporters, and their uptake potentials are the reasons for the tolerance of hiPSC-derived neurons to excitotoxicity.

[Evaluation of Low-dose Whole-body FDG PET with SiPM-based PET/CT Scanner: Visual and Semi-quantitative Analyses Using Random Sampling from Full-dose Scan Data].

PURPOSE: Sensitivity and count rate performance of the latest PET/CT scanners with a silicon photomultiplier (SiPM) have been substantially improved compared to scanners with a photomultiplier tube (PMT), thereby promising a low-dose whole-body PET scan with maintaining image quality. However, it is ethically difficult to verify the low-dose protocol in actual clinical settings. In this study, we investigated the effect of dose reduction on reconstructed images by using a low-dose simulation technique, i.e., reducing the number of events from the acquired data. METHOD: For 21 subjects who underwent whole-body 18F-FDG PET examination with an SiPM-based PET/CT scanner, Biograph Vision (Siemens Healthineers, Erlangen, Germany), at a dosage of 3.5 MBq/kg and a continuous bed motion speed of 1.1 mm/sec (the standard protocol in our hospital), the number of events in acquired list data (100%; "full-dose") was reduced to 50%, 25%, 12.5%, and 6.25% ("low-dose"). The low-dose reconstructed images were evaluated visually and physically with reference to the full-dose images. The physical evaluation was performed by calculating differences in SUVmax at abnormal uptake (n=54) between the full-dose and low-dose images. RESULT: The 25% data images were visually acceptable, and the difference in SUVmax between the 100% and 25% data images was 9.8±13.5%. CONCLUSION: Our results suggest that Biograph Vision is a feasible method to reduce conventional dose with the potential use of 25% data images.

Expression and function of estrogen receptors and estrogen-related receptors in the brain and their association with Alzheimer's disease.

While estrogens are well known for their pivotal role in the female reproductive system, they also play a crucial function in regulating physiological processes associated with learning and memory in the brain. Moreover, they have neuroprotective effects in the pathogenesis of Alzheimer's disease (AD). Importantly, AD has a higher incidence in older and postmenopausal women than in men, and estrogen treatment might reduce the risk of AD in these women. In general, estrogens bind to and activate estrogen receptors (ERs)-mediated transcriptional machineries, and also stimulate signal transduction through membrane ERs (mERs). Estrogen-related receptors (ERRs), which share homologous sequences with ERs but lack estrogen-binding capabilities, are widely and highly expressed in the human brain and have also been implicated in AD pathogenesis. In this review, we primarily provide a summary of ER and ERR expression patterns in the human brain. In addition, we summarize recent studies on their role in learning and memory. We then review and discuss research that has elucidated the functions and importance of ERs and ERRs in AD pathogenesis, including their role in Aß clearance and the reduction of phosphorylated tau levels. Elucidation of the mechanisms underlying ER- and ERR-mediated transcriptional machineries and their functions in healthy and diseased brains would provide new perspectives for the diagnosis and treatment of AD. Furthermore, exploring the potential role of estrogens and their receptors, ERs, in AD will facilitate a better understanding of the sex differences observed in AD, and lead to novel sex-specific therapeutic approaches.

Role of piRNA biogenesis and its neuronal function in the development of neurodegenerative diseases.

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), are caused by neuronal loss and dysfunction. Despite remarkable improvements in our understanding of these pathogeneses, serious worldwide problems with significant public health burdens are remained. Therefore, new efficient diagnostic and therapeutic strategies are urgently required. PIWI-interacting RNAs (piRNAs) are a major class of small non-coding RNAs that silence gene expression through transcriptional and post-transcriptional processes. Recent studies have demonstrated that piRNAs, originally found in the germ line, are also produced in non-gonadal somatic cells, including neurons, and further revealed the emerging roles of piRNAs, including their roles in neurodevelopment, aging, and neurodegenerative diseases. In this review, we aimed to summarize the current knowledge regarding the piRNA roles in the pathophysiology of neurodegenerative diseases. In this context, we first reviewed on recent updates on neuronal piRNA functions, including biogenesis, axon regeneration, behavior, and memory formation, in humans and mice. We also discuss the aberrant expression and dysregulation of neuronal piRNAs in neurodegenerative diseases, such as AD, PD, and ALS. Moreover, we review pioneering preclinical studies on piRNAs as biomarkers and therapeutic targets. Elucidation of the mechanisms underlying piRNA biogenesis and their functions in the brain would provide new perspectives for the clinical diagnosis and treatment of AD and various neurodegenerative diseases.

Stress granules sequester Alzheimer's disease-associated gene transcripts and regulate disease-related neuronal proteostasis.

Environmental and physiological stresses can accelerate Alzheimer's disease (AD) pathogenesis. Under stress, a cytoplasmic membraneless structure termed a stress granule (SG) is formed and is associated with various neurodegenerative disorders, including AD. SGs contain translationally arrested mRNAs, suggesting that impaired RNA metabolism in neurons causes AD progression; however, the underlying mechanism remains unclear. Here, we identified numerous mRNAs and long non-coding RNAs that are directly targeted by the SG core proteins G3BP1 and G3BP2. They redundantly target RNAs before and after stress conditions. We further identified RNAs within SGs, wherein AD-associated gene transcripts accumulated, suggesting that SGs can directly regulate AD development. Furthermore, gene-network analysis revealed a possible link between the sequestration of RNAs by SGs and the impairment of protein neurohomeostasis in AD brains. Together, our study provides a comprehensive RNA regulatory mechanism involving SGs, which could be targeted therapeutically to slow AD progression mediated by SGs.

Comparison of taste characteristics between koji mold-ripened cheese and Camembert cheese using an electronic tongue system.

Koji mold, classified in the genus Aspergillus, is used to produce traditional Japanese fermented foods such as miso, soy sauce, and sake. In recent years, the application of koji mold to cheese ripening has attracted attention, and cheese surface-ripened with koji mold (koji cheese) has been studied. In this study, to evaluate the taste characteristics of koji cheese, an electronic tongue system was employed to measure the taste values of cheese samples ripened using 5 strains of koji mold in comparison with commercial Camembert cheese. All koji cheese samples exhibited lower sourness and greater bitterness, astringency, saltiness, and umami richness than the Camembert cheese samples. The intensity of each taste characteristic differed depending on the koji mold strain. These results indicate that koji cheese has a different taste value than conventional mold-ripened cheese. Furthermore, the results also indicate that various taste characteristics can be achieved by selecting different koji molds.

Usefulness of a humanized tricellular static transwell blood-brain barrier model as a microphysiological system for drug development applications. - A case study based on the benchmark evaluations of blood-brain barrier microphysiological system.

Microphysiological system (MPS), a new technology for in vitro testing platforms, have been acknowledged as a strong tool for drug development. In the central nervous system (CNS), the blood‒brain barrier (BBB) limits the permeation of circulating substances from the blood vessels to the brain, thereby protecting the CNS from circulating xenobiotic compounds. At the same time, the BBB hinders drug development by introducing challenges at various stages, such as pharmacokinetics/pharmacodynamics (PK/PD), safety assessment, and efficacy assessment. To solve these problems, efforts are being made to develop a BBB MPS, particularly of a humanized type. In this study, we suggested minimal essential benchmark items to establish the BBB-likeness of a BBB MPS; these criteria support end users in determining the appropriate range of applications for a candidate BBB MPS. Furthermore, we examined these benchmark items in a two-dimensional (2D) humanized tricellular static transwell BBB MPS, the most conventional design of BBB MPS with human cell lines. Among the benchmark items, the efflux ratios of P-gp and BCRP showed high reproducibility in two independent facilities, while the directional transports meditated through Glut1 or TfR were not confirmed. We have organized the protocols of the experiments described above as standard operating procedures (SOPs). We here provide the SOPs with the flow chart including entire procedure and how to apply each SOP. Our study is important developmental step of BBB MPS towards the social acceptance, which enable end users to check and compare the performance the BBB MPSs.

[In vitro in vivo extrapolation (IVIVE) in safety pharmacology to improve human predictability -new evaluation systems for new drug modalities].

In the current drug development process, most safety pharmacological tests are animal experiments optimized for low molecular weight compounds. However, development trends have shifted to new modality drugs such as human specific mRNA, antisense oligonucleotides, and siRNA, etc., indicating that now the importance of the human predictability in safety pharmacology is more important than ever. In parallel with that, in vitro use of human cells, such as human iPS cell-derived tissue cells and chimeric mice with human hepatocytes, has been studied strenuously. In this review, we will discuss about IVIVE in safety pharmacology to improve human predictability in this trend of drug development.

[MPS for Blood Brain Barrier].

Blood brain barrier (BBB) is strong barrier specific to the brain vasculatures. BBB protects the brain from xenobiotics, while make it difficult to predict toxicokinetics/toxicodynamics, pharmacokinetics/pharmacodynamics, and efficiencies of new drugs in drug development. In this review, we will explain the physiological significance of BBB, the reason why the humanized BBB Micro Physiological System (MPS) is necessary, and the background technologies of BBB MPS. Because BBB MPS is the fusion of the engineering element technologies and the biological element technologies, we will explain the element technologies in both fields, respectively. We will also introduce the recent trends of BBB MPS to improve the human predictability: the shear stress in microfluidic models and the cellular architecture reproduction by three dimensional culture.

Leucine 434 is essential for docosahexaenoic acid-induced augmentation of L-glutamate transporter current.

Astrocytic excitatory amino acid transporter 2 (EAAT2) plays a major role in removing the excitatory neurotransmitter L-glutamate (L-Glu) from synaptic clefts in the forebrain to prevent excitotoxicity. Polyunsaturated fatty acids such as docosahexaenoic acid (DHA, 22:6 n-3) enhance synaptic transmission, and their target molecules include EAATs. Here, we aimed to investigate the effect of DHA on EAAT2 and identify the key amino acid for DHA/EAAT2 interaction by electrophysiological recording of L-Glu-induced current in Xenopus oocytes transfected with EAATs, their chimeras, and single mutants. DHA transiently increased the amplitude of EAAT2 but tended to decrease that of excitatory amino acid transporter subtype 1 (EAAT1), another astrocytic EAAT. Single mutation of leucine (Leu) 434 to alanine (Ala) completely suppressed the augmentation by DHA, while mutation of EAAT1 Ala 435 (corresponding to EAAT2 Leu434) to Leu changed the effect from suppression to augmentation. Other polyunsaturated fatty acids (docosapentaenoic acid, eicosapentaenoic acid, arachidonic acid, and α-linolenic acid) similarly augmented the EAAT2 current and suppressed the EAAT1 current. Finally, our docking analysis suggested the most stable docking site is the lipid crevice of EAAT2, in close proximity to the L-Glu and sodium binding sites, suggesting that the DHA/Leu434 interaction might affect the elevator-like slide and/or the shapes of the other binding sites. Collectively, our results highlight a key molecular detail in the DHA-induced regulation of synaptic transmission involving EAATs.

Comparison of the alkalizing abilities between 1.35% sodium bicarbonate solutions with and without dextrose in healthy calves.

The present study aimed to clarify the alkalizing ability of 1.35% isotonic sodium bicarbonate solution (ISBS), which did not contain dextrose, compared with that of 1.35% isotonic bicarbonate sodium solution containing 4.03% dextrose (ISBD) in healthy calves. The calves were intravenously administered with 20.7 mL/kg of the solutions for 30 min as the volume required to correct base deficit of 10 mM. ISBS increased the blood pH, HCO3-, and base excess from 7.44 ± 0.02, 29.6 ± 1.9 mM, and 5.3 ± 2.1 mM to 7.49 ± 0.02, 36.9 ± 2.3 mM, and 13.5 ± 2.6 mM respectively (P<0.05). These factors for the ISBD group increased from 7.41 ± 0.02, 29.0 ± 1.1 mM, and 4.5 ± 1.3 mM to 7.43 ± 0.02, 33.5 ± 1.9 mM, and 9.5 ± 1.7 mM (P<0.05), respectively. Furthermore, in the ISBD group, the relative plasma volume and blood glucose level increased while the K+ level decreased, which did not occur in the ISBS group. Therefore, the results revealed that ISBS had better alkalizing ability in calves than ISBD.

Nail insertion points in semi-extended nailing of tibial fractures and their influence on alignment: A retrospective cohort study comparing two nail insertion techniques.

INTRODUCTION: Semi-extended tibial nailing techniques include the extra-articular technique (EAT) and the patellar eversion technique (PET). These approaches differ regarding the exposure of the patellar retinaculum and the size of the surgical field. This study compared the postoperative alignment and intramedullary nailing entry points between the EAT and PET for tibial fractures. PATIENTS AND METHODS: A total of 54 patients (aged ≥18 years) who had undergone intramedullary nailing by the EAT (n = 29) or PET (n = 25) for a tibial shaft fracture were evaluated. The intramedullary nailing entry point and postoperative alignment were measured, and the 1-year postoperative follow-up results were compared. RESULTS: For the EAT and PET, the intramedullary nailing entry point was located at a mean distance of 4.04 mm medial to the optimal entry point and 0.27 mm lateral to the optimal entry point, respectively. The mean angular deformation observed in anteroposterior radiographs following surgery using the EAT and PET were 2.49° and 0.32° valgus, respectively. CONCLUSION: The intramedullary nailing entry point affected postoperative alignment. Intramedullary nailing may result in malalignment while performing the EAT due to the interference of the patella at the time of nailing.

Volatile and soluble metabolite profiles in surface-ripened cheeses with Aspergillus oryzae and Aspergillus sojae.

To determine the impact of traditional koji molds on chemical characteristics of soft-type natural cheese, novel surface mold-ripened cheeses with Aspergillus oryzae and Aspergillus sojae were studied by non-targeted metabolite profiling. Comprehensive water-soluble and volatile metabolite profiles of koji cheese were evaluated among five Aspergillus strains and other mold-ripened cheeses. Time-course changes in the metabolite profiles and degrading enzyme activities were also compared with those of an industrial Penicillium candidum starter culture. Koji cheeses differed from Camembert, Brie, and blue cheeses in higher lactic acid, amino acid, and acetoin levels and lower methyl ketone and volatile fatty acid levels. Time-course analysis revealed the associations of rapid accumulations of glutamic, aspartic, and 3-methylbutanoic acids and 3-methylbutanal with higher proteolytic activity, and methyl ketone and fatty acid derivative suppressions with lower lipolytic activity. Ethyl butanoate, diacetyl, and malic acid also characterized koji cheeses as strain-dependent metabolites. This study highlighted the key compositional difference derived from cheese ripening with Aspergillus strains. The findings could help quality improvements of koji cheese product.

Development of a three-dimensional blood-brain barrier network with opening capillary structures for drug transport screening assays.

The blood-brain barrier (BBB), a selective barrier regulating the active and passive transport of solutes in the extracellular fluid of the central nervous system, prevents the delivery of therapeutics for brain disorders. The BBB is composed of brain microvascular endothelial cells (BMEC), pericytes and astrocytes. Current in vitro BBB models cannot reproduce the human structural complexity of the brain microvasculature, and thus their functions are not enough for drug assessments. In this study, we developed a 3D self-assembled microvascular network formed by BMEC covered by pericytes and astrocyte end feet. It exhibited perfusable microvasculature due to the presence of capillary opening ends on the bottom of the hydrogel. It also demonstrated size-selective permeation of different molecular weights of fluorescent-labeled dextran, as similarly reported for in vivo rodent brain, suggesting the same permeability with actual in vivo brain. The activity of P-glycoprotein efflux pump was confirmed using the substrate Rhodamine 123. Finally, the functionality of the receptor-mediated transcytosis, one of the main routes for drug delivery of large molecules into the brain, could be validated using transferrin receptor (TfR) with confocal imaging, competition assays and permeability assays. Efficient permeability coefficient (Pe) value of transportable anti-TfR antibody (MEM-189) was seven-fold higher than those of isotype antibody (IgG1) and low transportable anti-TfR antibody (13E4), suggesting a higher TfR transport function than previous reports. The BBB model with capillary openings could thus be a valuable tool for the screening of therapeutics that can be transported across the BBB, including those using TfR-mediated transport.