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Abstract Recent developments in tissue clearing methods such as the passive clearing technique (PACT) have allowed three-dimensional analysis of biological structures in whole, intact tissues, thereby providing a greater understanding of spatial relationships and biological circuits. Nonetheless, the issues that remain in maintaining structural integrity and preventing tissue expansion/shrinkage with rapid clearing still inhibit the wide application of these techniques in hard bone tissues, such as femurs and tibias. Here, we present an optimized PACT-based bone-clearing method, Bone-mPACT+, that protects biological structures. Bone-mPACT+ and four different decalcifying procedures were tested for their ability to improve bone tissue clearing efficiency without sacrificing optical transparency; they rendered nearly all types of bone tissues transparent. Both mouse and rat bones were nearly transparent after the clearing process. We also present a further modification, the Bone-mPACT+ Advance protocol, which is specifically optimized for processing the largest and hardest rat bones for easy clearing and imaging using established tissue clearing methods.

Abstract This paper presents an asynchronous SAR ADC featuring a self‐timed track‐and‐hold (STH) architecture. The design aims to address the common timing issue of divider‐based clock generation, where the fixed‐time track‐and‐hold (FTH) period often results in incomplete conversions due to prolonged conversion times time due to comparator metastability. To alleviate the degradation of the ENOB induced by these delays, the proposed STH method is introduced so that more conversion period is secured without requiring a high‐speed input clock. Based on measurements, the proposed STH method achieves up to 0.7 bit improvement over the conventional FTH approach as conversion time increases.

Abstract Human mesenchymal stem cells (hMSCs)-derived extracellular vesicles (EVs) have been known to possess the features of the origin cell with nano size and have shown therapeutic potentials for regenerative medicine in recent studies as alternatives for cell-based therapies. However, extremely low production yield, unknown effects derived from serum impurities, and relatively low bioactivities on doses must be overcome for translational applications. As several reports have demonstrated the tunability of secretion and bioactivities of EVs, herein, we introduced three-dimensional (3D) culture and cell priming approaches for MSCs in serum-free chemically defined media to exclude side effects from serum-derived impurities. Aggregates (spheroids) with 3D culture dramatically enhanced secretion of EVs about 6.7 times more than cells with two-dimensional (2D) culture, and altered surface compositions. Further modulation with cell priming with the combination of TNF-α and IFN-γ (TI) facilitated the production of EVs about 1.4 times more than cells without priming (9.4 times more than cells with 2D culture without priming), and bioactivities of EVs related to tissue regenerations. Interestingly, unlike changing 2D to 3D culture, TI priming altered internal cytokines of MSC-derived EVs. Through simulating characteristics of EVs with bioinformatics analysis, the regeneration-relative properties such as angiogenesis, wound healing, anti-inflammation, anti-apoptosis, and anti-fibrosis, for three different types of EVs were comparatively analyzed using cell-based assays. The present study demonstrated that a combinatory strategy, 3D cultures and priming MSCs in chemically defined media, provided the optimum environments to maximize secretion and regeneration-related bioactivities of MSC-derived EVs without impurities for future translational applications.

Background : The severity of the coronavirus disease 2019 (COVID-19) pandemic has discouraged organ donation. However, the prevalence of COVID-19 in Korea was much lower in comparison to Western countries. With this, the authors decided to determine the real-world impact of COVID-19 on organ donation and transplantation in Korea. Methods : The number of kidney transplantations (KTs) and liver transplantations (LTs) performed in 2020 were compared with those in 2019 using the Korean Network for Organ Sharing database and Asan Medical Center (AMC) database. Results : The annual number of deceased donors (DDs) was 450 in 2019 compared to 478 in 2020. Monthly DD number was 37.5±5.9 in 2019 and 39.8±4.4 in 2020 (P=0.284). Annual number of DD kidney transplant (DDKT) was 794 in 2019 and 848 in 2020, and monthly number was 66.1±10.4 in 2019 and 70.7±9.8 in 2020 (P=0.285). The annual number of DDLT was 391 in 2019 and 395 in 2020, and the monthly number was 32.6±5.7, 2019 and 32.9±4.7 in 2020 (P=0.877). The annual number of living donor (LD) KT was 2,293 in 2019 and 1,432 in 2020, and the monthly number was 191.1±19.5 in 2019 and 119.3±11.7 in 2020 (P

Abstract Three-dimensional visualization of cellular and subcellular-structures in histological-tissues is essential for understanding the complexities of biological-phenomena, especially with regards structural and spatial relationships and pathologlical-diagnosis. Recent advancements in tissue-clearing technology, such as Magnified Analysis of Proteome (MAP), have significantly improved our ability to study biological-structures in three-dimensional space; however, their wide applicability to a variety of tissues is limited by long incubation-times and a need for advanced imaging-systems that are not readily available in most-laboratories. Here, we present optimized MAP-based method for paper-thin samples, Paper-MAP, which allow for rapid clearing and subsequent imaging of three-dimensional sections derived from various tissues using conventional confocal-microscopy. Paper-MAP successfully clear tissues within 1-day, compared to the original-MAP, without significant differences in achieved optical-transparency. As a proof-of-concept, we investigated the vasculature and neuronal-networks of a variety of human and rodent tissues processed via Paper-MAP, in both healthy and diseased contexts, including Alzheimer’s disease and glioma.

The advent of tissue clearing methods, in conjunction with novel high-resolution imaging techniques, has enabled the visualization of three-dimensional structures with unprecedented depth and detail. Although a variety of clearing protocols have been developed, little has been done to quantify their efficacies in a systematic, reproducible fashion. Here, we present two simple assays, Punching-Assisted Clarity Analysis (PACA)-Light and PACA-Glow, which use easily accessible spectroscopy and gel documentation systems to quantify the transparency of multiple cleared tissues simultaneously. We demonstrate the use of PACA-Light and PACA-Glow to compare twenty-eight tissue clearing protocols on rodent brains. We also show that regional differences exist in tissue transparency in the rodent brain, with cerebellar tissue consistently achieving lower clearing levels compared to the prefrontal or cerebral cortex across all protocols. This represents the largest comparative study of tissue clearing protocols to date, made possible by the high-throughput nature of our PACA platforms.

If a new drug candidate will be a mixture of enantiomers, both enantiomers should be separately studied for at least latent genotoxicity as early as possible since the thalidomide tragedy. Our group has recently reported that KCP-10043F (OZ-001) as a racemate (±)-3,4-dihydroquinazoline derivative strongly represses the proliferation of human A549 lung cancer cells by caspase-mediated apoptosis via STAT3 inactivation. To investigate the possible teratological effects of the two enantiomers of a racemic KCP-10043F, therefore chiral resolution of (±)-KCP-10043F was performed and subsequently followed by a series of chemical processes to afford the corresponding chiral diastereomers. By using 1H NMR anisotropy method, the absolute configuration (+)-KCP-10043F and (−)-KCP-10043F could be assigned as S and R configuration, respectively. The bacterial reverse mutation test (Ames test) for racemate (±)-KCP-10043F and its two enantiomers exhibited that all three stereoisomers were found to be nongenotoxic against five bacterial strains with/without metabolic activation. In addition, (R)-(−)-KCP-10043F displayed almost equal anticancer activity to (S)-(+)-KCP-10043F against three cancer cell lines. Based on these overall results, racemate KCP-10043F (OZ-001) could be used for our ongoing preclinical and clinical studies without the expensive asymmetric process and/or chiral separation.

Endothelialization by materials provides a promising approach for the rapid re-endothelialization of a cardiovascular implantation. Although previous studies have focused on improving endothelialization through the immobilization of bioactive molecules onto the surface of biodegradable implants, comparative studies of effective surface modification have not yet been reported. Here, we conducted a comparative study on the surface modification of poly(lactide-co-glycolide) (PLGA)-based composites to graft mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) using three different materials, fibronectin (FN), polyethylenimine (PEI), and polydopamine (PDA), which have different bond strengths of ligand–receptor interaction, ionic bond, and covalent bond, respectively. Further in vitro analysis exhibited that MSC-EVs released from all modified films sustainably, but the MSC-EVs grafted onto the surface coated with PEI are more effective than other groups in increasing angiogenesis and reducing the inflammatory responses in endothelial cells. Therefore, the overall results demonstrated that PEI is a desirable coating reagent for the immobilization of MSC-EVs on the surface of biodegradable implants.