A survey of the impact of COVID-19 on the management of animal experiments and laboratory animal facilities in Korea

The pandemic has affected the lives of people all over the world. The effects of the pandemic on laboratory animal facilities and their operations through this unusual global event are poorly understood. Here, we have applied a methodological framework of qualitative approach including semi-structured interviews to investigate laboratory animal operations in Korea and how it has shaped the on-going management and laboratory operations of such facilities. A total of fifty-two individuals, including members and administrators of the Institutional Animal Care and Use Committee (IACUC), researchers, and animal facility managers and staff, were surveyed through purposeful sampling. Survey questions explored how the pandemic impacted the IACUC and the functioning of animal facilities, and what steps to take in preparation of a future pandemic-like crisis. Our survey found evidence of an increase in animal experiments in Korea during the pandemic that correlated with increases in research funding during that period, such as for vaccine development. Also, operational challenges due to pandemic-related health issues in personnel were resolved through overtime, rather than by reducing facility operations. Moreover, a refinement of post-approval monitoring (PAM) practices was also discussed by respondents. Taken together, our study offers insights into animal facility operations during the pandemic and outlines recommendations for safeguarding operations in such future scenarios.

Double Emulsion-Mediated Delivery of Polyphenol Mixture Alleviates Atopic Dermatitis

Although the polyphenols have been studied to alleviate inflammation, there are still challenges to delivering the polyphenols with stabilized formulation due to their low water solubility and susceptibility to oxidation. Herein, the transdermal delivery system of polyphenol mixture (PM), including quercetin (Q), phloretin (P), and ellagic acid (E), is developed using double emulsion for applying to atopic dermatitis (AD). Through the in vitro anti-degranulation assay, the optimal molar ratio of each polyphenol (Q:P:E = 5:1:1) is obtained, and the PM shows at most a 43.6% reduction of degranulation of immune cells, which is the primary factor of AD. Moreover, the water-in-oil-in-water double emulsion (W/O/W) enhances the PM's stability and has a higher anti-degranulation effect than the oil-in-water emulsion (O/W). In the in vivo 1-chloro-2,4-dinitrobenzene (DNCB)-induced mice AD model, PM reduces more AD symptoms than every single polyphenol. The PM-encapsulated W/O/W (PM_W/O/W) shows the most effectiveness in AD by decreasing dermatitis score, i.e., skin/ear thickness, mast cells, and serum IgE level. Finally, this suggests that the findings on the optimal ratio of PM and double emulsion-based delivery would be beneficial in treating AD and can be applied to other allergic diseases.

Use of laboratory animals and issues regarding the procurement of animals for research in Korea

BACKGROUND

Laboratory animals remain critical to biomedical research, despite the increasing availability of alternative approaches. Indeed, scientists strive to reduce and refine and replace the use of laboratory animals, even in the face of public calls for ever-more stringent regulation for the protection and care of animals in research. This report outlines the current status and legal regulatory issues with regard to the procurement and use of animals for research in Korea.

RESULTS

The number of animals used for education and research purposes was increased nationwide, from 2.5 to 4.9 million in 2015 and 2021, respectively. When compared with figures from the UK, institutions in Korea were found to use more mammals such as mice and dogs. In our research, we identified three major issues concerning recent animal supply in Korea, particularly: (1) Purchase of dogs from unregistered animal supplier for a dog cloning project; (2) Purchase of dogs from an unclear source for veterinary education and training; (3) Illegal cat experiments using cats obtained from unauthorized routes.

CONCLUSIONS

Our findings support the notion that alternatives to laboratory animal research should be implemented. We conclude that improvements in the regulations and guidelines for animal suppliers, together with the recent introduction of legislation will improve animal safety and wellbeing of animals in laboratory research in Korea.

External validation of the biomarker based ABCD score in atrial fibrillation patients with a non gender CHA2DS2 VASc score 0 to 1, A Korean multicenter retrospective cohort

Background

Patients with low to intermediate risk atrial fibrillation (AF), defined as non-gender CHA2DS2-VASc score of 0–1, are still at risk of stroke. This study verified the usefulness of ABCD score (Age [≥60 years], B-type natriuretic peptide [BNP] or N-terminal pro-BNP [≥300 pg/ml], Creatinine clearance [<50 ml/min/1.73 m2], and Dimension of the left atrium [≥45 mm]) for stroke risk stratification in non-gender CHA2DS2-VASc score 0–1.

Methods

This multi-center cohort study retrospectively analyzed AF patients with non-gender CHA2DS2-VASc score 0–1. The primary endpoint was the incidence of stroke with or without anti-thrombotic treatment (ATT). An ABCD score was also validated.

Results

Overall, 2694 patients (56.3±9.5 years; female, 726 [26.9%]) were followed-up for 4.0±2.8 years. The overall stroke rate was 0.84/100 person-years (P-Y), stratified as follows: 0.46/100P-Y for an ABCD score 0; 1.02/100P-Y for an ABCD score≥1. The ABCD score was superior to the non-gender CHA2DS2-VASc score in stroke risk stratification (C-index=0.618, P=0.015; net reclassification improvement=0.576, P=0.040; integrated differential improvement=0.033, P=0.066). ATT was prescribed in 2353 patients (86.5%), and the stroke rate was significantly lower in patients receiving non-vitamin K antagonist oral anticoagulant (NOAC) therapy and an ABCD score≥1 than in those without ATT (0.44/100P-Y versus 1.55/100 P-Y; hazard ratio=0.26, 95% confidence interval 0.11–0.63, P=0.003).

Conclusion

The biomarker-based ABCD score demonstrated improved stroke risk stratification in AF patients with non-gender CHA2DS2-VASc score 0–1. Furthermore, NOAC with an ABCD score≥1 was associated with significantly lower stroke rate in AF patients with a non-gender CHA2DS2-VASc score 0–1.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Korean Disease Control and Prevention Agency

Exopolysaccharide of Enterococcus faecium L15 promotes the osteogenic differentiation of human dental pulp stem cells via p38 MAPK pathway

Background

Bone has important functions in the body. Several researchers have reported that the polysaccharides and lipopolysaccharide derived from microbes can promote osteogenic differentiation of stem cells. Enterococcus faecium, a lactic acid bacterium (LAB), produces several bioactive metabolites and has been widely applied in the food and nutraceutical industries. The exopolysaccharide (EPS) from LAB has also been extensively examined for its postbiotic effects and for its in vivo and in vitro functionalities. However, studies on promoting bone differentiation using polysaccharides from LAB are lacking. Therefore, the purpose of this study was to investigate the effect of E. faecium L15 extract and EPS on osteogenic differentiation of human dental pulp stem cells (hDPSCs) and to identify the underlying mechanisms.

Methods

hDPSCs were obtained from dental pulp tissue, and L15 extract and EPS were isolated from L15. Gene and protein expression of the osteogenic differentiation markers were analyzed with qPCR and western blotting and the possible signaling pathways were also investigated using western blotting. Osteogenic differentiation potential was examined by alkaline phosphatase (ALP) staining and alizarin red s (ARS) staining. In addition, osteogenic differentiation potential of L15 EPS was explored in ex vivo culture of neonate murine calvaria.

Results

The calcium deposition and ALP activity were enhanced by addition of L15 extract or EPS. The expression levels of RUNX2, ALP, and COL1A1 mRNA and the protein expression levels of RUNX2, ALP, and BMP4 were increased in hDPSCs treated with the L15 extract or EPS. The L15 EPS treatment enhanced phosphorylation of the p38 mitogen-activated protein kinase (MAPK). The L15 EPS-induced increases in RUNX2, ALP, and BMP4 expression were suppressed by the p38 MAPK inhibitor SB203580. The promoting effect of L15 EPS on osteogenic differentiation was not only seen in hDPSCs, but also in osteoblast precursors. ALP activity and the expression of RUNX2, ALP, and COL1A1 increased in the L15 EPS-treated osteoblast precursors. In addition, L15 EPS increased bone thickness of neonate murine calvaria in ex vivo culture.

Conclusions

The stimulatory effect of L15 extract and EPS on osteogenic differentiation occurred through the p38 MAPK pathway, and L15 EPS enhanced new bone formation in neonate murine calvaria. These data suggest that L15 EPS has therapeutic potential applicable to bone regeneration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03151-0.

Effect of LOXL2 on metastasis through remodeling of the cell surface matrix in non-small cell lung cancer cells

Lung cancer is the prominent cause of cancer-associated death primarily because of distant metastatic disease. The metastatic potential of non-small cell lung cancer (NSCLC) is associated with tumor cell aggregation. However, the systemic mechanotransduction mechanism by which tumor cells dynamically aggregate and disseminate is poorly understood, especially in NSCLC. In this study, we examine whether the cell surface matrix plays an important role in metastasis. We used poly-2-hydroxyethyl methacrylate-based 3D spheroid formation methods to mimic in vivo metastatic lesions. Supra-structural analysis of human NSCLC A549 cells stained with ruthenium red for transmission electron microscopy (TEM) showed that glycocalyx surrounding the cell surface in 2D culture decreases in 3D culture. Comprehensive gene expression analysis revealed that the genes associated with cell adhesion were distinctly enriched in A549 cell spheroids. Of these, downregulation of the tumor metastatic microenvironment facilitator LOXL2, a copper-dependent enzyme catalyzing posttranslational oxidative deamination of peptidyl lysine, was of special interest. Knockdown of LOXL2 thickened the cell surface matrix in 2D culture and impaired compact aggregate formation in 3D culture. Moreover, A549 cell spheroids with endogenous overexpression of LOXL2 increased their dissemination on basement extracellular matrix Matrigel. Overall, these data imply that cell detachment-downregulated LOXL2 contributes to cell surface matrix remodeling, leading to collective dissemination of free-floating aggregates.

Operational issues of the Institutional Animal Care and Use Committee in Korea

Korean Institutional Animal Care and Use Committee (IACUC) is currently facing some operational pressing issues. 1) Review of the animal protocol containing controversial technology. 2) Review of the multi-institution animal protocol. 3) Review of veterinary clinical trials for client-owned animals. 4) Delay the review process in large institutions with a single IACUC. Here, the following three solutions are proposed to address the above issues. 1) Establishment of public IACUC. 2) Establishment of the Veterinary Clinical Study Committee as an advisory body to the IACUC. 3) Operating multiple committees rather than increasing the number of committee members on a single committee.

The status and issues of the Institutional Animal Care and Use Committee of Seoul National University: from its establishment to the present day

The Institutional Animal Care and Use Committee (IACUC) of Seoul National University (SNU) plays a key role in monitoring and managing the humane use of animals in scientific research. Here, as one of the pioneers of the IACUC in Korea, we reported SNU-IACUC operations and activities including committee establishment and legal formulation, protocol review, and post-approval monitoring of protocols, which the IACUC has undertaken in the last decade. In addition, legal regulations and improvements were also discussed, and encompassed the limited number of committee members and the single IACUC policy in Korea. As of December, 2020, amendments are on the table at the National Assembly. We also emphasized the independent nature of the IACUC in protecting activities, including approval and monitoring animal experiments, and its public role in narrowing the knowledge gap between society and scientists. Thus, the aim of this report is to help society and scientists understand the operations of the SNU-IACUC and its role in animal welfare.

Enterococcus faecium L-15 Extract Enhances the Self-Renewal and Proliferation of Mouse Skin-Derived Precursor Cells

Lactic acid bacteria (LAB) in the gastrointestinal tract have beneficial health effects. LAB activate the proliferation of intestinal stem cells and speed the recovery of damaged intestinal cells, but little is known about effect of LAB on other adult stem cells. In this study, a cell-free extract of Enterococcus faecium L-15 (L15) was exposed to mouse skin-derived precursor cells (SKPs), and the changes in characteristics associated with proliferation and self-renewal capacity were investigated. L15 increased the size of the spheres and the proliferation rate of SKPs. Cell cycle analysis revealed that cells in the S-phase increased after treatment with L15. In the L15-treated group, the total number of spheres significantly increased. The expression level of pluripotency marker genes also increased, while the mesenchymal lineage-related differentiation marker genes significantly decreased in the L15-treated group. The PI3K/Akt signaling pathway was activated by L15 in SKPs. These results indicate that L15 enhances proliferation and self-renewal of SKPs and may be used as a supplement for stem cell maintenance or application of stem cell therapy. This is the first report to investigate the functional effects of E. faecium on the proliferation and self-renewal capacity of SKPs.

A Rho Kinase (ROCK) Inhibitor, Y-27632, Inhibits the Dissociation-Induced Cell Death of Salivary Gland Stem Cells

Salivary gland stem cells (SGSCs) are potential cell sources for the treatment of salivary gland diseases. The control of cell survival is an essential factor for applying stem cells to regenerative medicine or stem cell-based research. The purpose of this study was to investigate the effects of the ROCK inhibitor Y-27632 on the survival of SGSCs and its underlying mechanisms. SGSCs were isolated from mouse submandibular glands and cultured in suspension. Treatment with Y-27632 restored the viability of SGSCs that was significantly decreased during isolation and the subsequent culture. Y-27632 upregulated the expression of anti-apoptotic protein BCL-2 in SGSCs and, in the apoptosis assay, significantly reduced apoptotic and necrotic cell populations. Matrigel was used to mimic the extracellular environment of an intact salivary gland. The expression of genes regulating apoptosis and the ROCK signaling pathway was significantly reduced when SGSCs were embedded in Matrigel. SGSCs cultured in Matrigel and treated with Y-27632 showed no difference in the total numbers of spheroids and expression levels of apoptosis-regulating genes. Matrigel-embedded SGSCs treated with Y-27632 increased the number of spheroids with budding structures and the expression of acinar cell-specific marker AQP5. We demonstrate the protective effects of Y-27632 against dissociation-induced apoptosis of SGSCs during their culture in vitro.

AQP3 Increases Intercellular Cohesion in NSCLC A549 Cell Spheroids through Exploratory Cell Protrusions

Tumor cell aggregation is critical for cell survival following the loss of extracellular matrix attachment and dissemination. However, the underlying mechanotransduction of clustering solitary tumor cells is poorly understood, especially in non-small cell lung cancers (NSCLC). Here, we examined whether cell surface protrusions played an important role in facilitating the physical contact between floating cells detached from a substrate. We employed poly-2-hydroxyethyl methacrylate-based 3D culture methods to mimic in vivo tumor cell cluster formation. The suprastructural analysis of human NSCLC A549 cell spheroids showed that finger-like protrusions clung together via the actin cytoskeleton. Time-lapse holotomography demonstrated that the finger-like protrusions of free-floating cells in 3D culture displayed exploratory coalescence. Global gene expression analysis demonstrated that the genes in the organic hydroxyl transport were particularly enriched in the A549 cell spheroids. Particularly, the knockdown of the water channel aquaporin 3 gene (AQP3) impaired multicellular aggregate formation in 3D culture through the rearrangement of the actomyosin cytoskeleton. Moreover, the cells with reduced levels of AQP3 decreased their transmigration. Overall, these data indicate that cell detachment-upregulated AQP3 contributes to cell surface protrusions through actomyosin cytoskeleton remodeling, causing the aggressive aggregation of free-floating cells dependent on the property of the substratum and collective metastasis.

Oral intake of Lactobacillus plantarum L-14 extract alleviates TLR2- and AMPK-mediated obesity-associated disorders in high-fat-diet-induced obese C57BL/6J mice

OBJECTIVES

Whether periodic oral intake of postbiotics positively affects weight regulation and prevents obesity-associated diseases in vivo is unclear. This study evaluated the action mechanism of Lactobacillus plantarum L-14 (KTCT13497BP) extract and the effects of its periodic oral intake in a high-fat-diet (HFD) mouse model.

MATERIALS AND METHODS

Mouse pre-adipocyte 3T3-L1 cells and human bone marrow mesenchymal stem cells (hBM-MSC) were treated with L-14 extract every 2 days during adipogenic differentiation, and the mechanism underlying anti-adipogenic effects was analysed at cellular and molecular levels. L-14 extract was orally administrated to HFD-feeding C57BL/6J mice every 2 days for 7 weeks. White adipose tissue was collected and weighed, and liver and blood serum were analysed. The anti-adipogenic mechanism of exopolysaccharide (EPS) isolated from L-14 extract was also analysed using Toll-like receptor 2 (TLR2) inhibitor C29.

RESULTS

L-14 extract inhibited 3T3-L1 and hBM-MSC differentiation into mature adipocytes by upregulating AMPK signalling pathway in the early stage of adipogenic differentiation. The weight of the HFD + L-14 group (31.51 ± 1.96 g) was significantly different from that of the HFD group (35.14 ± 3.18 g). L-14 extract also significantly decreased the serum triacylglycerol/high-density lipoprotein cholesterol ratio (an insulin resistance marker) and steatohepatitis. In addition, EPS activated the AMPK signalling pathway by interacting with TLR2, consequently inhibiting adipogenesis.

CONCLUSIONS

EPS from L-14 extract inhibits adipogenesis via TLR2 and AMPK signalling pathways, and oral intake of L-14 extract improves obesity and obesity-associated diseases in vivo. Therefore, EPS can be used to prevent and treat obesity and metabolic disorders.

Exopolysaccharide Isolated from Lactobacillus plantarum L-14 Has Anti-Inflammatory Effects via the Toll-Like Receptor 4 Pathway in LPS-Induced RAW 264.7 Cells

Inflammation is a biological response of the immune system to defend the body from negative stimulation. However, the excessive inflammatory response can damage host tissues and pose serious threats. Exopolysaccharide (EPS), one of the postbiotics, is secreted from lactic acid bacteria. Although many studies have described the beneficial effects of EPS, such as its anti-inflammatory and anti-oxidant effects, its underlying mechanisms have remained to be poorly understood. Thus, we identified that EPS obtained from Lactobacillus plantarum L-14 was a homogeneous polysaccharide primarily comprised of glucose. To examine these anti-inflammatory effects, an inflammatory response was induced by lipopolysaccharide (LPS) administration to mouse macrophage RAW 264.7 cells that were pretreated with EPS. The anti-inflammatory effects of EPS were identified by analyzing the changes within inflammatory markers at the molecular level. We demonstrate here that EPS suppressed proinflammatory mediators, such as cyclooxygenase-2, interleukin-6, tumor necrosis factor-α, and interleukin-1β, and downregulated the expression of an inducible nitric oxide synthase known to lead to oxidative stress. It was also confirmed that EPS had anti-inflammatory effects by blocking the interaction of LPS with Toll-like receptor 4 (TLR4), as demonstrated by using the known TLR4 inhibitor TAK-242. In addition, we found that EPS itself could suppress the expression of TLR4. Consequently, our data suggest that EPS can be a potential target for the development of natural product-derived medicine for treating inflammatory diseases related to TLR4.

GRIM-19 Ameliorates Multiple Sclerosis in a Mouse Model of Experimental Autoimmune Encephalomyelitis with Reciprocal Regulation of IFNγ/Th1 and IL-17A/Th17 Cells

The protein encoded by the Gene Associated with Retinoid-Interferon-Induced Mortality-19 (GRIM-19) is located in the mitochondrial inner membrane and is homologous to the NADH dehydrogenase 1-alpha subcomplex subunit 13 of the electron transport chain. Multiple sclerosis (MS) is a demyelinating disease that damages the brain and spinal cord. Although both the cause and mechanism of MS progression remain unclear, it is accepted that an immune disorder is involved. We explored whether GRIM-19 ameliorated MS by increasing the levels of inflammatory cytokines and immune cells; we used a mouse model of experimental autoimmune encephalomyelitis (EAE) to this end. Six-to-eight-week-old male C57BL/6, IFNγ-knockout (KO), and GRIM-19 transgenic mice were used; EAE was induced in all strains. A GRIM-19 overexpression vector (GRIM19 OVN) was electrophoretically injected intravenously. The levels of Th1 and Th17 cells were measured via flow cytometry, immunofluorescence, and immunohistochemical analysis. IL-17A and IFNγ expression levels were assessed via ELISA and quantitative PCR. IL-17A expression decreased and IFNγ expression increased in EAE mice that received injections of the GRIM19 OVN. GRIM-19 transgenic mice expressed more IFNγ than did wild-type mice; this inhibited EAE development. However, the effect of GRIM-19 overexpression on the EAE of IFNγ-KO mice did not differ from that of the empty vector. GRIM-19 expression was therapeutic for EAE mice, elevating the IFNγ level. GRIM-19 regulated the Th17/Treg cell balance.

Brown adipose tissue ameliorates autoimmune arthritis via inhibition of Th17 cells

The functions of adipose tissue are associated with autoimmune diseases, such as rheumatoid arthritis (RA). Some studies have shown that the three compositions of adipose tissue (white, brown, and beige) have different functions. Brown adipose tissue (BAT) is known to secrete several factors that differ from those in white adipose tissue. This suggests that BAT might have potential positive advantages in the physiology of autoimmune diseases. We compared the functions of collagen-induced arthritis mice-derived BAT (CIA BAT) with normal mice-derived BAT. DBA/1J mice (6-7 weeks of age) were immunized by intradermal injection at the base of the tail with 100 μg of bovine type II collagen (CII) emulsified in complete Freund's adjuvant. Immunized mice then received booster immunizations by intraperitoneal injection with 100 μg of CII in incomplete Freund's adjuvant. We transplanted CIA BAT and normal BAT into CIA recipient mice. After transplantation, we measured the functions of CIA BAT and normal BAT in mice. Normal BAT-transplanted mice showed significantly lower scores of bone damage, inflammation, and cartilage damage. The proinflammatory cytokines in normal BAT-transplanted mice, such as IL-12, IL-17, IL-6, and tumor necrosis factor-α (TNF-α), tended to decrease. Microarray analysis showed that the PI3K-AKT signaling pathway and IL-17 levels of CIA BAT tissues were significantly higher than those of normal BAT tissues. These results suggest that the transplantation of normal brown fat may have a therapeutic effect in RA patients.

Expression of polo-like kinase 1 in pre-implantation stage murine somatic cell nuclear transfer embryos

Somatic cell nuclear transfer (SCNT) has various applications in research, as well as in the medical field and animal husbandry. However, the efficiency of SCNT is low and the accurate mechanism of SCNT in murine embryo development is unreported. In general, the developmental rate of SCNT murine embryos is lower than in vivo counterparts. In previous studies, polo-like kinase 1 (Plk1) was reported to be a crucial element in cell division including centrosome maturation, cytokinesis, and spindle formation. In an initial series of experiments in this study, BI2536, a Plk1 inhibitor, was treated to in vivo-fertilized embryos and the embryos failed to develop beyond the 2-cell stage. This confirmed previous findings that Plk1 is crucial for the first mitotic division of murine embryos. Next, we investigated Plk1's localization and intensity by immunofluorescence analysis. In contrast to normally developed embryos, SCNT murine embryos that failed to develop exhibited two types of Plk1 expressions; a low Plk1 expression pattern and ectopic expression of Plk1. The results show that Plk1 has a critical role in SCNT murine embryos. In conclusion, this study demonstrated that the SCNT murine embryos fail to develop beyond the 2-cell stage, and the embryos show abnormal Plk1 expression patterns, which may one of the main causes of developmental failure of early SCNT murine embryos.

The relationship between non-cognitive student attributes and academic achievements in a flipped learning classroom of a pre-dental science course

PURPOSE

The purpose of this study was to examine whether non-cognitive student attributes such as learning style and personality type affected academic performance in a flipped learning classroom of a pre-dental undergraduate science course.

METHODS

'Biodiversity and Global Environment,' a 15-week, 3-credit course, was designed as a flipped class in Seoul National University School of Dentistry in 2017. Second-year pre-dental students were required to enroll in the course and to engage in online learning and in-class discussion. The Kolb's Learning Style Inventory and the Myers-Briggs Type Indicator were conducted to measure non-cognitive student factors. Independent samples t-test and multivariate regression analyses were used to examine the relationships between self-rated measurements and academic achievement.

RESULTS

More than half of the students enrolled in the flipped science course had an assimilator learning style (50%), followed by convergers (24%), accommodators (16%), and divergers (10%), and their personality types were dominated by the introverted, sensing, thinking, and judging types, respectively. Examining group differences using the t-test demonstrated a significant relationship between the diverger group and higher academic success. In particular, the multivariate regression analysis indicated that both thinking types and female students performed better in discussion than feeling types and male students.

CONCLUSION

To operate the flipped learning classroom more effectively in medical and dental education, the instructor should carefully develop and apply a more tailored facilitation and relevant assessment by considering student learning styles and personality types.

SOX2, a stemness gene, induces progression of NSCLC A549 cells toward anchorage-independent growth and chemoresistance to vinblastine

Background

Non-small cell lung cancer (NSCLC) is difficult to treat successfully. This intractability is mainly due to the cancer progressing through invasion, metastasis, chemotherapeutic resistance and relapse. Stemness has been linked to the various steps of cancer progression in a variety of tumors, yet little is known regarding its role in NSCLC.

Purpose

In this study, we sought to determine the role of SOX2, a master regulator of pluripotency, in the growth of extracellular matrix (ECM)-detached cells during cancer progression.

Methods

We established a three-dimensional (3D) Poly-2-hydroxyethyl methacrylate (poly-HEMA) culture of lung adenocarcinoma (LUAD) A549 cells as an ECM-detached cell growth model and examined the role of stemness genes using siRNA and small molecule inhibitor in comparison to standard two dimensional (2D) culture.

Results

In poly-HEMA culture, A549 cells formed substratum-detached spheroids with characteristics of intermediate epithelial to mesenchymal transition (EMT) and exhibited greater expression of SOX2 than did control 2D cells. Knockdown of SOX2 markedly suppressed the growth of A549 cell aggregates in poly-HEMA culture conditions and furthermore increased their sensitivity to the anticancer drug vinblastine with concomitant downregulation of the activity of the anti-apoptotic AKT kinase. Interestingly, a small molecule, RepSox, which replaces SOX2, stimulated A549 cell growth in poly-HEMA 3D culture condition.

Conclusion

Our findings strongly indicate that SOX2 contributes to anchorage-independent growth and chemoresistance via its downstream signaling mediator AKT kinase during the disease progression of NSCLC. SOX2 may therefore be an invaluable therapeutic target of NSCLC.

Sonic hedgehog signalling regulates the self-renewal and proliferation of skin-derived precursor cells in mice

Objectives

The sonic hedgehog (Shh) signalling pathway has an important role in the maintenance of various stem cells and organogenesis during development. However, the effect of Shh in skin‐derived precursors (SKPs), which have the capacity for multipotency and self‐renewal, is not yet clear. The present study investigated the effects of the Shh signalling pathway on the proliferation and self‐renewal of murine SKPs (mSKPs).

Methods

The Shh signalling pathway was activated by treatment with purmorphamine (Shh agonist) or recombinant Shh in mSKPs. Cyclopamine (Shh antagonist) or GANT‐61 (Gli inhibitor) was used to inhibit the pathway. Western blot, qPCR, and immunofluorescence were used to analyse the expression of genes related to self‐renewal, stemness, epithelial‐mesenchymal transition (EMT) and the Shh signalling pathway. In addition, cell proliferation and apoptosis were examined.

Results

Inhibiting the Shh signalling pathway reduced mSKP proliferation and sphere formation, but increased apoptosis. Activating this signalling pathway produced opposite results. The Shh signalling pathway also controlled the EMT phenotype in mSKPs. Moreover, purmorphamine recovered the self‐renewal and proliferation of aged mSKPs.

Conclusion

Our results suggest that the Shh signalling pathway has an important role in the proliferation, self‐renewal and apoptosis of mSKPs. These findings also provide a better understanding of the cellular mechanisms underlying SKP self‐renewal and apoptosis that allow more efficient expansion of SKPs.

Holding of bovine blastocysts at suprazero temperatures using small molecules

Although assisted reproductive technology (ART) currently exists, the only embryo preservation technology that is available is cryopreservation. In the present study, small molecules were used to hold embryos at room temperature. The basic medium for embryo holding for a short period of time at 4 °C, 10 °C and 20 °C consisted of 1% BSA non-cryopreservation medium (BNC) instead of fetal bovine serum. To maintain survival and prevent damage during embryo incubation, three candidate small molecules were selected—CHIR99021, Y-27632 and Thiazovivin—and their concentrations were optimized. The viability and hatching rate of embryos incubated at 10 °C were greater for Y-27632-BNC and CHIR99021+Y-27632-BNC compared to BNC. However, the rate was lower for Thiazovivin-BNC compared to BNC. Although there were no surviving embryos after incubation at 20 °C, the viability and hatching rate of embryos significantly increased in Y-27632-BNC and CHIR99021+Y-27632-BNC compared to BNC. The pregnancy rate of embryos incubated at 20 °C was also greater in the CHIR99021+Y-27632-BNC group compared to that in the frozen group. The mechanism by which small molecules enhance survival of embryos during incubation was investigated, and expression of heat shock protein 70 was observed to increase. The findings of this work may be useful in improving ART in the agricultural field.

Flipped-learning course design and evaluation through student self-assessment in a predental science class

PURPOSE

This study explores how to design a flipped classroom for a predental science course and evaluate its course through student self-assessment in order to provide practical implications for flipped learning in an undergraduate level.

METHODS

Second- and third-year predental students in the Seoul National University School of Dentistry enrolled in Biodiversity and Global Environment, a 15-week, three-credit course based on a flipped learning model. At the end of the course, the students were asked to rate their self-directed learning, attitude toward social media, discussion skills, learning readiness, and class satisfaction. Out of the 82 predental students, 61 (74.3%) answered the survey. Pearson correlation and multivariate regression analyses were employed to examine the relationship between the self-rated measurements and the performance scores.

RESULTS

The majority of the students felt somewhat more prepared than the medium level before the class (mean score of 3.17 out of 5.00), whereas they expressed relatively low preference concerning social media use and attitude (mean score of 2.49). Thus, it was found that learning readiness was significantly associated with both discussion skills and class satisfaction. In particular, multivariate regression analysis confirmed that learning readiness had a significant influence on learning outcomes.

CONCLUSION

This study offered insights into how to design a flipped learning course in terms of predental students' preference and their learning readiness. Although learning success in a flipped classroom depends on the students' self-perceived level of preparedness, much still remains to be achieved in order to apply social media benefits in a flipped learning context.

Improvement of pregnancy rate by intrauterine administration of dexamethasone and recombinant human leukemia inhibitory factor at the time of embryo transfer in cattle

Bovine embryos (day 5) were cultured to day 10 with or without 100 ng/mL PGF2α in medium supplemented with control; 100 nM Dex; 1,000 U/mL recombinant human leukemia inhibitory factor (rhLIF); or Dex+rhLIF. Although the rates to development to the blastocyst were not significantly different among groups, the hatching rate after additional culture with Dex +/or rhLIF was significantly higher in all supplemented groups than the control (p < 0.05). In the presence of PGF2α, the hatching rate was significantly restored in all supplemented groups relative to the group treated with only PGF2α and the control (p < 0.05). Embryo transfer (ET) was performed with blastocysts (day 7). PGF2α levels of control recipient cows were significantly higher in the circulatory blood samples collected 60 min after ET than in samples collected 60 min before ET (p < 0.005), and were decreased in cows injected with loading medium supplemented with Dex+rhLIF (p < 0.005). Pregnancy rate was significantly higher in the ET group that received supplemented embryo-loading medium than in the non-supplemented control (p < 0.05). The intrauterine administration of Dex and rhLIF at ET prevented increased PGF2α in circulatory blood and resulted in enhanced pregnancy rate.

Microarray analysis of embryo-derived bovine pluripotent cells: The vulnerable state of bovine embryonic stem cells

Although there are many studies about pluripotent stem cells, little is known about pluripotent pathways and the difficulties of maintaining the pluripotency of bovine cells in vitro. Here, we investigated differently expressed genes (DEG) in bovine embryo-derived stem-like cells (eSLCs) from various origins to validate their distinct characteristics of pluripotency and differentiation. We identified core pluripotency markers and additional markers which were not determined as pluripotency markers yet in bovine eSLCs. Using the KEGG database, TGFβ, WNT, and LIF signaling were related to the maintenance of pluripotency. In contrast, some DEGs related to the LIF pathway were down-regulated, suggesting that reactivation of the pathway may be required for the establishment of true bovine embryonic stem cells (ESCs). Interestingly, oncogenes were co-down-regulated, while tumor suppressor genes were co-up-regulated in eSLCs, implying that this pattern may induce abnormal teratomas. These data analyses of signaling pathways provide essential information on authentic ESCs in addition to providing evidence for pluripotency in bovine eSLCs.

Postweaning changes in the expression of chemerin and its receptors in calves are associated with the modification of glucose metabolism

Chemerin, originally known as a chemoattractant derived from adipose tissue and the liver, has been reported to have regulatory functions in gluconeogenesis, peripheral insulin sensitivity, and insulin secretion. This study was conducted to assess the postweaning changes in expression of this cytokine and its physiological role in the modification of glucose metabolism associated with weaning. Eighteen tissue samples were collected from Holstein calves (90 d of age; n = 4) to investigate the tissue distributions of chemerin and its receptors genes. was highly expressed in the liver, and secreted chemerin protein was found in the plasma. Among the receptors of chemerin, and were ubiquitously expressed whereas was predominantly expressed in the liver. The changes in glucose metabolism and expression of these genes after weaning were assessed by comparing suckling calves (n = 6) and weaned calves (n = 8) of Japanese Black cattle. No significant difference was observed in plasma glucose levels between suckling and weaned calves (P = 0.22), whereas the plasma level of total ketone bodies was significantly higher in weaned calves (P < 0.01). Plasma levels of insulin and cortisol did not differ between suckling and weaned calves. The mRNA levels of certain key enzymes involved in hepatic gluconeogenesis were also altered; for instance, level was lower in postweaning calves (P < 0.05) and () level tended to be higher after weaning (P = 0.08). However, was not altered after weaning. The plasma levels of hepatic stress indicators were also changed, with aspartate transaminase, alanine transaminase, and lactate dehydrogenase being significantly elevated in postweaning calves (P < 0.05). Chemerin protein in liver tissue was less abundant in weaned calves (P < 0.05), although there were no changes in its transcript levels. The abundance of plasma chemerin protein did not change after weaning (P = 0.95). In summary, these data indicate that as a consequence of weaning, which causes physiological stress and alters hepatic metabolism, chemerin protein expression within the liver is downregulated, indicating that chemerin plays a role in the upregulation of hepatic expression via its inhibitory effect on hepatic gluconeogenesis.

Murine somatic cell nuclear transfer using reprogrammed donor cells expressing male germ cell-specific genes

In vivo-matured mouse oocytes were enucleated, and a single murine embryonic fibroblast (control or reprogrammed by introducing extracts from murine testis tissue, which showed expression of male germ cell-specific genes) was injected into the cytoplasm of the oocytes. The rate of blastocyst development and expression levels of Oct-4, Eomes and Cdx-2 were not significantly different in both experimental groups. However, the expression levels of Nanog, Sox9 and Glut-1 were significantly increased when reprogrammed cells were used as donor nuclei. Increased expression of Nanog can be supportive of complete reprogramming of somatic cell nuclear transfer murine embryos. The present study suggested that donor cells expressing male germ cell-specific genes can be reconstructed and can develop into embryos with normal high expression of developmentally essential genes.

In vitro culture of stem-like cells derived from somatic cell nuclear transfer bovine embryos of the Korean beef cattle species, HanWoo

We established and maintained somatic cell nuclear transfer embryo-derived stem-like cells (SCNT-eSLCs) from the traditional Korean beef cattle species, HanWoo (Bos taurus coreanae). Each SCNT blastocyst was placed individually on a feeder layer with culture medium containing three inhibitors of differentiation (3i). Primary colonies formed after 2-3 days of culture and the intact colonies were passaged every 5-6 days. The cells in each colony showed embryonic stem cell-like morphologies with a distinct boundary and were positive to alkaline phosphatase staining. Immunofluorescence and reverse transcription-polymerase chain reaction analyses also confirmed that these colonies expressed pluripotent markers. The colonies were maintained over 50 passages for more than 270 days. The cells showed normal karyotypes consisting of 60 chromosomes at Passage 50. Embryoid bodies were formed by suspension culture to analyse in vitro differentiation capability. Marker genes representing the differentiation into three germ layers were expressed. Typical embryonal carcinoma was generated after injecting cells under the testis capsule of nude mice, suggesting that the cultured cells may also have the potential of in vivo differentiation. In conclusion, we generated eSLCs from SCNT bovine embryos, using a 3i system that sustained stemness, normal karyotype and pluripotency, which was confirmed by in vitro and in vivo differentiation.

Transdifferentiation of mouse adipose-derived stromal cells into acinar cells of the submandibular gland using a co-culture system

A loss of salivary gland function often occurs after radiation therapy in head and neck tumors, though secretion of saliva by the salivary glands is essential for the health and maintenance of the oral environment. Transplantation of salivary acinar cells (ACs), in part, may overcome the side effects of therapy. Here we directly differentiated mouse adipose-derived stromal cells (ADSCs) into ACs using a co-culture system. Multipotent ADSCs can be easily collected from stromal vascular fractions of adipose tissues. The isolated ADSCs showed positive expression of markers such as integrin beta-1 (CD29), cell surface glycoprotein (CD44), endoglin (CD105), and Nanog. The cells were able to differentiate into adipocytes, osteoblasts, and neural-like cells after 14 days in culture. ADSCs at passage 2 were co-cultured with mouse ACs in AC culture medium using the double-chamber (co-culture system) to avoid mixing the cell types. The ADSCs in this co-culture system expressed markers of ACs, such as α-amylases and aquaporin5, in both mRNA and protein. ADSCs cultured in AC-conditioned medium also expressed AC markers. Cellular proliferation and senescence analyses demonstrated that cells in the co-culture group showed lower senescence and a higher proliferation rate than the AC-conditioned medium group at Days 14 and 21. The results above imply direct conversion of ADSCs into ACs under the co-culture system; therefore, ADSCs may be a stem cell source for the therapy for salivary gland damage.

Y-27632, a ROCK inhibitor, delays senescence of putative murine salivary gland stem cells in culture

OBJECTIVE

A loss of functional salivary glands often occurs after radiotherapy for head and neck tumour, and causes many problems in oral health. Recently, the use of salispheres, which consist of salivary gland stem cells (SGSCs), has been suggested as therapy for these problems. However, an insufficient number of cells can be obtained and cultured for cell transplantation. In the present study, salispheres were propagated and passaged by suspension culture to acquire a sufficient number of SGSCs for cell therapy.

DESIGN

The relationship between sphere formation and the degree of cellular senescence was investigated by analysing senescence-associated β-galactosidase activity and the expression of senescence-related markers such as CDKN2A (p16) and p21. Because the sphere formation potential of SGSCs was decreased and the senescence of the cells was increased after passaging subculture, Y-27632, a Rho-associated kinase inhibitor, was used to treat the passaging subculture to aid the proliferation of the cells in culture.

RESULTS

The number of spheres was higher in the Y-27632 treatment group than in the control group, and the expression of c-Kit, a proliferation marker, was also increased. In addition, the expression of p16 and p21 proteins tended to be lower in the Y-27632 group.

CONCLUSION

Y-27632 suppresses the expression of senescence-related proteins and enhances cellular proliferation. This study points to the possibility of scaling-up the therapeutic use of SGSCs, which requires a large amount of cells.

A nanoscale ridge/groove pattern arrayed surface enhances adipogenic differentiation of human supernumerary tooth-derived dental pulp stem cells in vitro

OBJECTIVE

The aim of this study was to establish human dental pulp stem cells (hDPSCs) from supernumerary teeth and determine the effects of a 350-nm nano-patterned surface on adipogenic and osteogenic differentiation of hDPSCs.

DESIGN

Several surface markers were analysed by FACS to confirm the isolated cells as hDPSCs. To demonstrate the effects of a nano-patterned surface on the differentiation of hDPSCs, the cells were cultured on a nano-patterned surface with or without adipogenic or osteogenic induction factors. Cells were then stained with Oil red O or Alizarin red, and the lineage specific genes LPL and Runx-2 were analysed by real-time PCR at 3, 6 and 9 days after culture.

RESULTS

The hDPSCs on a nano-patterned surface showed a linear arrangement compared to irregular cells on a conventional surface. During adipogenic differentiation, more Oil red O stained cells were found in the nano-patterned group than in the conventional group. On the other hand, there was no significant difference in Alizarin red staining between the nano-pattern and conventional surface groups after induction of osteogenic differentiation. Gene expression analyses revealed significantly higher expression of LPL in the nano-patterned group than in the conventional group, whereas Runx-2 expression was higher in the conventional group than in the nano-patterned group.

CONCLUSION

This study showed that a nano-patterned surface may be able to enhance adipogenic differentiation of hDPSCs by altering their morphology and gene expression patterns, whereas the same surface may inhibit or suppress osteogenic differentiation of the cells.

A simplified one-step nuclear transfer procedure alters the gene expression patterns and developmental potential of cloned porcine embryos

Various somatic cell nuclear transfer (SCNT) techniques for mammalian species have been developed to adjust species-specific procedures to oocyte-associated differences among species. Species-specific SCNT protocols may result in different expression levels of developmentally important genes that may affect embryonic development and pregnancy. In the present study, porcine oocytes were treated with demecolcine that facilitated enucleation with protruding genetic material. Enucleation and donor cell injection were performed either simultaneously with a single pipette (simplified one-step SCNT; SONT) or separately with different pipettes (conventional two-step SCNT; CTNT) as the control procedure. After blastocysts from both groups were cultured in vitro, the expression levels of developmentally important genes (OCT4, NANOG, EOMES, CDX2, GLUT-1, PolyA, and HSP70) were analyzed by real-time quantitative polymerase chain reaction. Both the developmental rate according to blastocyst stage as well as the expression levels CDX2, EOMES, and HSP70 were elevated with SONT compared to CTNT. The genes with elevated expression are known to influence trophectoderm formation and heat stress-induced arrest. These results showed that our SONT technique improved the development of SCNT porcine embryos, and increased the expression of genes that are important for placental formation and stress-induced arrest.