Utility of Exosomes in Ischemic and Hemorrhagic Stroke Diagnosis and Treatment.

Stroke is the leading cause of death and neurological disorders worldwide. However, diagnostic techniques and treatments for stroke patients are still limited for certain types of stroke. Intensive research has been conducted so far to find suitable diagnostic techniques and treatments, but so far there has been no success. In recent years, various studies have drawn much attention to the clinical value of utilizing the mechanism of exosomes, low toxicity, biodegradability, and the ability to cross the blood-brain barrier. Recent studies have been reported on the use of biomarkers and protective and recovery effects of exosomes derived from stem cells or various cells in the diagnostic stage after stroke. This review focuses on publications describing changes in diagnostic biomarkers of exosomes following various strokes and processes for various potential applications as therapeutics.

Single-Cell Transcriptome Analysis as a Promising Tool to Study Pluripotent Stem Cell Reprogramming.

Cells are the basic units of all organisms and are involved in all vital activities, such as proliferation, differentiation, senescence, and apoptosis. A human body consists of more than 30 trillion cells generated through repeated division and differentiation from a single-cell fertilized egg in a highly organized programmatic fashion. Since the recent formation of the Human Cell Atlas consortium, establishing the Human Cell Atlas at the single-cell level has been an ongoing activity with the goal of understanding the mechanisms underlying diseases and vital cellular activities at the level of the single cell. In particular, transcriptome analysis of embryonic stem cells at the single-cell level is of great importance, as these cells are responsible for determining cell fate. Here, we review single-cell analysis techniques that have been actively used in recent years, introduce the single-cell analysis studies currently in progress in pluripotent stem cells and reprogramming, and forecast future studies.

Albumin-binding photosensitizer capable of targeting glioma via the SPARC pathway.

BACKGROUND: Malignant glioma is among the most lethal and frequently occurring brain tumors, and the average survival period is 15 months. Existing chemotherapy has low tolerance and low blood-brain barrier (BBB) permeability; therefore, the required drug dose cannot be accurately delivered to the tumor site, resulting in an insufficient drug effect. METHODS: Herein, we demonstrate a precision photodynamic tumor therapy using a photosensitizer (ZnPcS) capable of binding to albumin in situ, which can increase the permeability of the BBB and accurately target glioma. Albumin-binding ZnPcS was designed to pass through the BBB and bind to secreted protein acidic and rich in cysteine (SPARC), which is abundant in the glioma plasma membrane. RESULTS: When the upper part of a mouse brain was irradiated using a laser (0.2 W cm- 2) after transplantation of glioma and injection of ZnPcS, tumor growth was inhibited by approximately 83.6%, and the 50% survival rate of the treatment group increased by 14 days compared to the control group. In glioma with knockout SPARC, the amount of ZnPcS entering the glioma was reduced by 63.1%, indicating that it can target glioma through the SPARC pathway. CONCLUSION: This study showed that the use of albumin-binding photosensitizers is promising for the treatment of malignant gliomas.

Urinary exosomal microRNA profiling in type 2 diabetes patients taking dipeptidyl peptidase-4 inhibitor compared with sulfonylurea.

BACKGROUND: Dipeptidyl peptidase-4 (DPP-4) inhibitor has been reported to have kidney-protective benefits. To elucidate how antidiabetic agents prevent diabetic kidney disease progression, it is important to investigate their effect on the kidney environment in type 2 diabetes mellitus (DM) patients. Herein, we investigated the expression pattern of urinary exosome-derived microRNA (miRNA) in patients taking a combination of DPP-4 inhibitor and metformin (DPP-4 inhibitor group) and compared them with patients taking a combination of sulfonylurea and metformin (sulfonylurea group). METHODS: This was a prospective study involving 57 patients with type 2 DM (DPP-4 inhibitor group, n = 34; sulfonylurea group, n = 23) and healthy volunteers (n = 7). We measured urinary exosomal miRNA using the NanoString nCounter miRNA array (NanoString Technologies) across the three groups (n = 4 per each group) and validated findings using real-time polymerase chain reaction. RESULTS: Twenty-one differentially expressed candidate miRNAs were identified, and six (let-7c-5p, miR-23a-3p, miR-26a-3p, miR-30d, miR-205, and miR-200a) were selected for validation. Validation showed no significant difference in miRNA expression between the DPP-4 inhibitor and sulfonylurea groups. Only miR-23a-3p was significantly overexpressed in the diabetes group compared with the control group (DPP-4 inhibitor vs. control, p = 0.01; sulfonylurea vs. control, p = 0.007). This trend was consistent even after adjusting for age, sex, and body mass index. CONCLUSION: There was no significant difference in urine exosome miRNA expression between diabetic participants taking DPP-4 inhibitor and those taking sulfonylurea. The miR-23a levels were higher in diabetic participants than in nondiabetic controls.

Profiling of Metabolic Differences between Hematopoietic Stem Cells and Acute/Chronic Myeloid Leukemia.

Although many studies have been conducted on leukemia, only a few have analyzed the metabolomic profiles of various leukemic cells. In this study, the metabolomes of THP-1, U937, KG-1 (acute myelogenous leukemia, AML), K562 (chronic myelogenous leukemia, CML), and cord blood-derived CD34-positive hematopoietic stem cells (HSC) were analyzed using gas chromatography-mass spectrometry, and specific metabolic alterations were found using multivariate statistical analysis. Compared to HSCs, leukemia cell metabolomes were found to have significant alterations, among which three were related to amino acids, three to sugars, and five to fatty acids. Compared to CML, four metabolomes were observed specifically in AML. Given that overall more metabolites are present in leukemia cells than in HSCs, we observed that the activation of glycolysis and oxidative phosphorylation (OXPHOS) metabolism facilitated the incidence of leukemia and the proliferation of leukemic cells. Analysis of metabolome profiles specifically present in HSCs and leukemia cells greatly increases our basic understanding of cellular metabolic characteristics, which is valuable fundamental knowledge for developing novel anticancer drugs targeting leukemia metabolism.

Characterization of Endoplasmic Reticulum (ER) in Human Pluripotent Stem Cells Revealed Increased Susceptibility to Cell Death upon ER Stress.

Human pluripotent stem cells (hPSCs), such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have a well-orchestrated program for differentiation and self-renewal. However, the structural features of unique proteostatic-maintaining mechanisms in hPSCs and their features, distinct from those of differentiated cells, in response to cellular stress remain unclear. We evaluated and compared the morphological features and stress response of hPSCs and fibroblasts. Compared to fibroblasts, electron microscopy showed simpler/fewer structures with fewer networks in the endoplasmic reticulum (ER) of hPSCs, as well as lower expression of ER-related genes according to meta-analysis. As hPSCs contain low levels of binding immunoglobulin protein (BiP), an ER chaperone, thapsigargin treatment sharply increased the gene expression of the unfolded protein response. Thus, hPSCs with decreased chaperone function reacted sensitively to ER stress and entered apoptosis faster than fibroblasts. Such ER stress-induced apoptotic processes were abolished by tauroursodeoxycholic acid, an ER-stress reliever. Hence, our results revealed that as PSCs have an underdeveloped structure and express fewer BiP chaperone proteins than somatic cells, they are more susceptible to ER stress-induced apoptosis in response to stress.

Hyperthermia Disturbs and Delays Spontaneous Differentiation of Human Embryoid Bodies.

Various types of stress stimuli have been shown to threaten the normal development of embryos during embryogenesis. Prolonged heat exposure is the most common stressor that poses a threat to embryo development. Despite the extensive investigation of heat stress control mechanisms in the cytosol, the endoplasmic reticulum (ER) heat stress response remains unclear. In this study, we used human embryonic stem cells (hESCs) to examine the effect of heat stress on early embryonic development, specifically alterations in the ER stress response. In a hyperthermic (42 °C) culture, ER stress response genes involved in hESC differentiation were induced within 1 h of exposure, which resulted in disturbed and delayed differentiation. In addition, hyperthermia increased the expression levels of activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP) genes, which are associated with the protein kinase RNA-like endoplasmic reticulum kinase (PERK) signaling pathway. Furthermore, we demonstrated that tauroursodeoxycholic acid, a chemical chaperone, mitigated the delayed differentiation under hyperthermia. Our study identified novel gene markers in response to hyperthermia-induced ER stress on hESCs, thereby providing further insight into the mechanisms that regulate human embryogenesis.

Facile and Scalable Fabrication of Flexible Reattachable Ionomer Nanopatterns by Continuous Multidimensional Nanoinscribing and Low-temperature Roll Imprinting.

We develop a facile route to the scalable fabrication of flexible reattachable ionomer nanopatterns (RAINs) by continuous nanoinscribing and low-temperature roll imprinting, which are repeatedly attachable to and detachable from arbitrarily shaped surfaces. First, by sequentially performing continuous nanoinscribing over a polymer substrate along the multiple directions, we readily create the multidimensional nanopattern, which otherwise demands complex nanofabrication. After its transfer to an elastomer pad for use as a soft nanoimprinting stamp, we then conduct a low-temperature roll imprinting of the ionomer film to fabricate a flexible and highly transparent RAIN. Reversible loosening of ionic units in the ionomer material at the mild temperature as low as ∼60-70 °C enables the faithful nanopatterning over thermosensitive organic compounds and fragile materials under a slight pressure. The excellent adhesion purely emerging from ionic interactions uniquely realizes the conformal attachability and clean detachability of RAINs for universal targets in ambient conditions, particularly beneficial for individual wearable and mobile devices requiring the user-specific "on/off" of the nanopattern-driven functionalities. As one vivid example, we demonstrate that a single light-emitting device can be switched from the focused pointer to the widespread flashlight depending on the RAIN application upon user's purpose.

MiR-9 Controls Chemotactic Activity of Cord Blood CD34⁺ Cells by Repressing CXCR4 Expression.

Improved approaches for promoting umbilical cord blood (CB) hematopoietic stem cell (HSC) homing are clinically important to enhance engraftment of CB-HSCs. Clinical transplantation of CB-HSCs is used to treat a wide range of disorders. However, an improved understanding of HSC chemotaxis is needed for facilitation of the engraftment process. We found that ectopic overexpression of miR-9 and antisense-miR-9 respectively down- and up-regulated C-X-C chemokine receptor type 4 (CXCR4) expression in CB-CD34＋ cells as well as in 293T and TF-1 cell lines. Since CXCR4 is a specific receptor for the stromal cell derived factor-1 (SDF-1) chemotactic factor, we investigated whether sense miR-9 and antisense miR-9 influenced CXCR4-mediated chemotactic mobility of primary CB CD34＋ cells and TF-1 cells. Ectopic overexpression of sense miR-9 and antisense miR-9 respectively down- and up-regulated SDF-1-mediated chemotactic cell mobility. To our knowledge, this study is the first to report that miR-9 may play a role in regulating CXCR4 expression and SDF-1-mediated chemotactic activity of CB CD34＋ cells.

Effect of Oxygen on the Structural/Electrical Properties of NIZO Films on Transparent Flexible Substrates.

Thin film transparent oxides have attracted considerable attention over the last few decades for transparent electronic applications, such as flat panel displays, solar cells, touch-pads, and mobile devices. Metallic doped InZnO (IZO) films have been suggested for the transparent layer exhibiting semiconducting or metallic properties because of its controllable mobility and excellent electrical properties, but they show a degradation of the electrical performance under bending conditions. This study assessed Ni doped IZO (NIZO) films as a flexible transparent electrode on different flexible transparent substrates for flexible electronic applications. Thin NIZO films were deposited on cellulose, PES and glass substrates using a sputtering system with a single NIZO target (In2O3 73.8/ZnO 15.7/NiO 10.5 mol.%) at room temperature. During deposition of the NIZO films, the total flow rate of the carrier gas was maintained using a regulating system. The effects of the oxygen content in the carrier gas on the structural, electrical and optical properties of the thin films deposited on flexible substrates was characterized. The results highlight the feasibility of the transparent NIZO oxide layer on flexible substrates as a flexible electrode with a relatively high sheet resistance, which is strongly related to the crystallographic structure and oxygen content during the film deposition process.

Analysis of loss of heterozygosity in Korean patients with keratoacanthoma.

Loss of heterozygosity (LOH) has been established as an important genetic mechanism giving rise to malignant neoplasia. The mechanism of LOH has been shown to cause basal cell carcinoma and malignant melanoma as well as other types of skin cancer. A few studies on LOH in sporadic keratoacanthomas have been reported. The purpose of this study was to investigate the significance of LOH in the pathogenesis of sporadic keratoacanthomas developed in 10 Korean patients. The presents of LOH at 7 microsatellite markers (D2S286, D3S1317, D5S346, D9S160, D9S171, D10S185, and D17S261) were evaluated in sporadic keratoacanthomas. LOH was found in only 1 of 10 cases at D10S185. The low frequency of LOH detected in this study suggests that LOH may not be significant in the induction of sporadic keratoacanthomas.