Feasibility of methotrexate discontinuation following tocilizumab and methotrexate combination therapy in patients with long-standing and advanced rheumatoid arthritis: a 3-year observational cohort study.

OBJECTIVES: Methotrexate (MTX) is associated with extensive side effects, including myelosuppression, interstitial pneumonia, and infection. It is, therefore, critical to establish whether its administration is required after achieving remission with tocilizumab (TCZ) and MTX combination therapy in patients with rheumatoid arthritis (RA). Therefore, the aim of this multicenter, observational, cohort study was to evaluate the feasibility of MTX discontinuation for the safety of these patients. METHODS: Patients with RA were administered TCZ, with or without MTX, for 3 years; those who received TCZ+MTX combination therapy were selected. After remission was achieved, MTX was discontinued without flare development in one group (discontinued [DISC] group, n = 33) and continued without flare development in another group (maintain [MAIN] group, n = 37). The clinical efficacy of TCZ+MTX therapy, patient background characteristics, and adverse events were compared between groups. RESULTS: The disease activity score in 28 joints-erythrocyte sedimentation rate (DAS28-ESR) at 3, 6, and 9 months was significantly lower in the DISC group (P < .05, P < .01, and P < .01, respectively). Further, the DAS28-ESR remission rate at 6 and 9 months and Boolean remission rate at 6 months were significantly higher in the DISC group (P < .01 for all). Disease duration was significantly longer in the DISC group (P < .05). Furthermore, the number of patients with stage 4 RA was significantly higher in the DISC group (P < .01). CONCLUSIONS: Once remission was achieved, MTX was discontinued in patients who responded favorably to TCZ+MTX therapy, despite the prolonged disease duration and stage progression.

Development of the ultra-weak chemiluminescence method based on luminol reaction for use in the detection of ultra-trace levels of blood.

In this study, we focused on ultra-weak chemiluminescence (uwCL) measurements and aimed to develop a blood detection method at trace levels, that are difficult to observe using a conventional luminol reaction method (visual observation). Furthermore, we investigated sampling methods that could detect trace bloodstains from the field in our laboratory settings. To achieve these highly sensitive detection levels in the uwCL measurements, the optimal measurement conditions were established as follows: the luminol reaction solution chosen was a mixture of 6.0 × 10-3% luminol/1.5 × 10-2% sodium hydroxide solution and 1.5 × 10-2% hydrogen peroxide water (6:1); the temperature in the sample chamber was set to 20 °C; the sample chamber was filled with an oxygen displacement atmosphere; the sample chamber was filled with 3 mL of 0.01% sodium hydroxide solution prior to the experiment, and the measurement wavelength was set to 460 nm. Using the developed method, blood diluted to 12.5 million-fold (8.0 ng equivalent of the absolute weight of whole blood) was detectable, and high linearity (r = 0.9986) between uwCL intensity and whole blood equivalent was observed in the range of 8.0-100 ng. In contrast, the detection limit of the conventional method was 1.0 µg of the whole blood equivalent. Thus, the uwCL method was approximately 125 times more sensitive than the conventional method. In addition, we demonstrated that the sampling method of wiping with a melamine sponge soaked in a 10% sodium dodecyl sulfate solution is effective for sampling evidence materials at an appraisal site suspected of having traces of adhered blood.

The usefulness of OK-432 for the treatment of postoperative chylothorax in a low-birth-weight infant with trisomy 18.

Chylothorax is a rare but life-threatening condition in neonates. We herein report the successful use of OK-432 for a low-birth-weight infant with trisomy 18 who developed refractory chylothorax after thoracic surgery. Increasing the concentration of OK-432 seems useful in cases with a lot of pleural effusion.

Usefulness of Living Donor Liver Transplantation for Patients After Undergoing the Kasai Operation for Biliary Atresia.

BACKGROUND: Living donor liver transplantation (LDLT) has been actively performed for patients with poor clearance of jaundice after the Kasai operation for biliary atresia (BA). The present study clarified the usefulness of LDLT for BA. MATERIALS AND METHODS: Between 2000 and 2020, 24 patients (late group) underwent radical surgery for BA in our institute. The overall survival rate, native liver survival rate, and proportion of LDLT in the late group were retrospectively compared with those of 47 patients treated before 1999 (early group). P values <.05 was considered statistically significant. RESULTS: The overall survival rates at 5, 10, and 15 years were 57%, 54%, and 49%, respectively, in the early group and 100%, 100%, and 100% in the late group (P < .001). The native liver survival rates at 5, 10, and 15 years were 57%, 52%, and 39%, respectively, in the early group and 57%, 49%, and 42% (P = .993) in the late group. In the early group, LDLT was performed in 7 of 47 patients (15%), and the overall survival rate after LDLT was 71%. In the late group, LDLT was performed in 11 of 24 patients (46%), and the overall survival rate after LDLT was 100%. CONCLUSIONS: The long-term outcomes after the Kasai operation for BA have improved in recent years. There were no marked differences in long-term native liver survival before and after 2000. LDLT was actively introduced for patients with poor clearance of jaundice after the Kasai operation, and the survival rate significantly improved.

Management of refractory chylothorax in the neonatal intensive care unit: A 22-year experience.

BACKGROUND: The aim was to assess the therapeutic strategy of patients with chylothorax in a neonatal intensive care unit. METHODS: Twenty-eight infants with chylothorax were included in this study. Their clinical characteristics and outcomes were reviewed retrospectively. RESULTS: The male-to-female ratio was 1:1. The mean gestational age and birthweight were 35.1 ± 3.5 weeks and 2,692 ± 791 g, respectively. Eighteen patients were diagnosed with congenital chylothorax; chylothorax occurred postoperatively in 10 patients. Chromosomal anomalies were diagnosed in 8 patients. Six patients received surgical therapy, such as pleurodesis, thoracic duct ligation, or lymphaticovenous anastomosis. Two patients required surgery due to resistance to pleurodesis. In surgically managed patients, the daily maximum amount of pleural effusion (mL)/bodyweight (kg) ratio was significantly larger than in non-surgically managed patients: 229.0 ± 180.5 versus 59.7 ± 49.2 mL/kg. In the receiver operating characteristic analysis of the daily maximum amount of pleural effusion/bodyweight ratio, the area under the curve was 0.889 when the cut-off value was 101 mL/kg, and the sensitivity was 0.8333 and the specificity was 0.8095 (P = 0.0059). CONCLUSIONS: Pleurodesis using OK432 could become a surgical first-line therapy for chylothorax even for neonates. It was important to initiate pleurodesis for refractory chylothorax at an earlier stage. A daily chylous effusion/bodyweight ratio of >101 mL/kg was a good predictor and seemed to be a useful parameter for prompt surgical intervention.

Usefulness of the Monti-Malone procedure as a reconstruction of the antegrade continence enema procedure: a case report.

BACKGROUND: The antegrade continence enema (ACE) procedure is effective for severe constipation in patients with spina bifida and can improve quality of life (QOL). The Monti-Malone procedure (MM), which is a method of creating an enema tract from the colon, has been reported as an alternative to the ACE procedure when the appendix cannot be used. We report the usefulness of MM as a reconstruction of the antegrade continence enema procedure. CASE PRESENTATION: Our patient was a 22-year-old man with congenital spina bifida and hydrocephalus. Ventriculoperitoneal (VP) shunt surgery was performed immediately after birth, and preventative appendectomy was carried out during VP shunt repair when 4 months old. At 5 years of age, the ACE procedure using a balloon-button gastrostomy tube was performed for intractable chronic constipation. Simple management was expected, but after 17 years of age, he experienced increased stool leakage around the gastrostomy tube and his QOL declined due to difficulty in managing the ACE. Therefore, reconstruction of the ACE procedure by MM was performed. After reconstruction, the ACE performed well without any complications. The patient is currently satisfied because management of the ACE is easier than before, and his QOL has markedly improved without stool leakage and dermatitis. CONCLUSIONS: MM is less likely to cause complications and is useful as a reconstruction of the ACE procedure.

Residual Analysis of Aflatoxins in Spice by HPLC Coupled with Solid-Phase Dispersive Extraction and Solid-Phase Fluorescence Derivatization Method.

BACKGROUND: Aflatoxins (AFs) are carcinogenic mycotoxins. A simple, quick, and accurate method for the micro-analysis of AFs in foodstuffs, especially spices, is needed. OBJECTIVE: A sophisticated pretreatment method that combines solid-phase dispersive extraction (SPDE) and solid-phase fluorescence derivatization using immunoaffinity (IA) gel as the solid phase was developed to analyze AFs in spices simply, quickly, and sensitively by liquid chromatography with fluorescence detection. METHOD: White and black pepper samples were extracted with a mixed solution of methanol/water (4:1) and then diluted with 7% aqueous solution of Triton-X. The solution was subjected to cleanup by SPDE using IA gel. Trifluoroacetic acid was added to the IA gel for on-site solid-phase fluorescence derivatization. RESULTS: Chromatograms containing well-separated peaks and few interference peaks from contaminants were obtained. The method detection limit of AFs in white and black pepper was 0.15-0.29 ng/g. Repeatability and intermediate precision were <10% and <15%, respectively, and accuracy was 61.7-87.8%. In addition, inter-laboratory precision was <29% and mean recovery was 61.5-76.7%. A favorable z-score of |Z| ≦ 1 was obtained in seven laboratories, although one laboratory gave 2 < |Z| < 3. CONCLUSIONS: The validity, reliability, practicality, and robustness of the developed method were verified. HIGHLIGHTS: By using SPDE and solid-phase fluorescence derivatization in combination for AF analysis, fluorescence derivatization during cleanup was realized, leading to simplification of the pretreatment operation.

Circulating natural antibodies against 3'-sialyllactose complement the diagnostic performance of CA19-9 for the early detection of pancreatic ductal adenocarcinoma.

BACKGROUND: Pancreatic ductal adenocarcinoma is a devastating malignancy with an extremely poor prognosis. Although the most widely used biomarker for pancreatic cancer is carbohydrate antigen CA19-9, it is elevated mainly in the late stage of pancreatic cancer. Some serum natural antibodies against carbohydrates have been shown to be possible diagnostic markers for cancer. OBJECTIVE: This study was conducted to determine whether the level of natural antibodies against carbohydrates fluctuates in pancreatic ductal adenocarcinoma. METHODS: Serum from pancreatic cancer subjects (n= 55) and 43 subjects free of malignant disease were studied. The contents of natural antibodies against sialyl glycans and CA19-9 in serum were determined by enzyme-linked immunosorbent assay. RESULTS: The level of serum anti-3'-sialyllactose antibodies in pancreatic cancer subjects was significantly lower than that in healthy controls. In contrast, the amounts of serum antibodies against other sialyl glycans were comparable between the two groups. Concentration of serum anti-3'-sialyllactose IgG provided excellent AUC of 0.86, with sensitivity 82%, specificity 81%, and accuracy 82%. The combination of serum anti-3'-sialyllactose IgG with CA19-9 improved the sensitivity of pancreatic cancer detection at an early stage. CONCLUSIONS: Natural antibodies against 3'-sialyllactose constitute a promising biomarker for pancreatic cancer detection. The measurement of serum anti-3'-sialyllactose antibodies could play a supportive role in diagnostics and complement the performance of CA19-9 for the early detection of pancreatic ductal adenocarcinoma.

Epidermal growth factor receptor/heme oxygenase-1 axis is involved in chemoresistance to cisplatin and pirarubicin in HepG2 cell lines and hepatoblastoma specimens.

PURPOSE: To investigate the possibility that the antioxidant stress protein Heme oxygenase-1 (HO-1) is involved in the acquisition of chemoresistance in cisplatin and pirarubicin (CITA) therapy. METHODS: Human hepatoblastoma-derived cell line (HepG2) was used to generate a knockdown cell line of HO-1 by small interfering RNA (siRNA). Expression of HO-1, epidermal growth factor receptor (EGFR), Akt, and extracellular signal-regulated kinase1/2 (ERK1/2) was examined by Western blot. The cytotoxic effect of cisplatin, pirarubicin, and EGFR inhibitor was examined by trypan blue staining. In human hepatoblastoma specimens (n = 5), changes of HO-1 expression were examined immunohistochemically before and after CITA therapy. RESULTS: HO-1 expression in HepG2 cells was increased by the treatment of cisplatin (CDDP) and pirarubicin (THP) dose-dependently. In HO-1 knockdown HepG2 cells, the HO-1 was not expressed and the percentage of trypan blue-positive cells (dead cells) was significantly increased after treatment of CDDP and THP. The EGFR inhibitor decreased the levels of HO-1, phospho-Akt and phospho-ERK1/2 in HepG2 cells. Combination treatment of EGFR inhibitor with CDDP and THP increased the cytotoxic effect in HepG2 cells. In human hepatoblastoma specimens, 4 of the 5 patients (80%) showed HO-1 expression changed much stronger in the viable tumor cells after CITA therapy. CONCLUSION: The cytotoxic effects of CDDP and THP were both enhanced under HO-1 knockdown conditions as well as under conditions that inhibit the activation pathway of HO-1 by EGFR inhibitors. EGFR/HO-1 axis may be involved in acquiring chemoresistance in HepG2 cell lines as well as in human hepatoblastoma.

Identification of a Novel Bone Marrow Cell-Derived Accelerator of Fibrotic Liver Regeneration Through Mobilization of Hepatic Progenitor Cells in Mice.

Granulocyte colony stimulating factor (G-CSF) has been reported to ameliorate impaired liver function in patients with advanced liver diseases through mobilization and proliferation of hepatic progenitor cells (HPCs). However, the underlying mechanisms remain unknown. We previously showed that G-CSF treatment increased the number of bone marrow (BM)-derived cells migrating to the fibrotic liver following repeated carbon tetrachloride (CCl4 ) injections into mice. In this study, we identified opioid growth factor receptor-like 1 (OGFRL1) as a novel BM cell-derived accelerator of fibrotic liver regeneration in response to G-CSF treatment. Endogenous Ogfrl1 was highly expressed in the hematopoietic organs such as the BM and spleen, whereas the liver contained a relatively small amount of Ogfrl1 mRNA. Among the peripheral blood cells, monocytes were the major sources of OGFRL1. Endogenous Ogfrl1 expression in both the peripheral blood monocytes and the liver was decreased following repeated CCl4 injections. An intrasplenic injection of cells overexpressing OGFRL1 into CCl4 -treated fibrotic mice increased the number of HPC and stimulated proliferation of hepatic parenchymal cells after partial resection of the fibrotic liver. Furthermore, overexpression of OGFRL1 in cultured HPC accelerated their differentiation as estimated by increased expression of liver-specific genes such as hepatocyte nuclear factor 4α, cytochrome P450, and fatty acid binding protein 1, although it did not affect the colony forming ability of HPC. These results indicate a critical role of OGFRL1 in the mobilization and differentiation of HPC in the fibrotic liver, and administration of OGFRL1-expressing cells may serve as a potential regenerative therapy for advanced liver fibrosis. Stem Cells 2019;37:89-101.

The performance of an in vitro skin sensitisation test, IL-8 Luc assay (OECD442E), and the integrated approach with direct peptide reactive assay (DPRA).

In all current in vitro skin sensitisation assays, DMSO is used to dissolve water-insoluble chemicals. However, our previous study suggested the superiority of the modified IL-8 Luc assay (mIL-8 Luc), in which X-VIVOTM 15 is used to dissolve chemicals, over the original assay using DMSO (oIL-8 Luc). In this study, to confirm the superiority of the mIL-8 Luc, we first increased the number of chemicals examined and demonstrated the superiority of the mIL-8 Luc, in which the mIL-8 Luc provided 87.6% of sensitivity, 74.2% of specificity, and 84.6% of accuracy. Next, to clarify the cause of false negative judgment by the mIL-8 Luc, we examined the effects of physical properties of chemicals on judgment. The results demonstrated that high molecular weight, high LogKo/w, or poor water solubility, did not cause false negative judgment. When it was accepted as an OECD test guideline, the criteria of the mIL-8 Luc to determine sensitisers were modified to further decrease false negative judgment by poor solubility. By applying the new criteria, the test guideline IL-8 Luc assay (tgIL-8 Luc) improved sensitivity but decreased specificity and increased the number of chemicals that cannot be judged. To overcome this problem, we examined a simple combination of the tgIL-8 Luc with direct peptide reactive assay (DPRA), which could improve specificity and decrease the number of the chemicals that cannot be judged. These data suggest that the tgIL-8 Luc is a promising in vitro skin sensitisation assay in combination with other in vitro or in chemico methods.

A novel irreversible FLT3 inhibitor, FF-10101, shows excellent efficacy against AML cells with FLT3 mutations.

An activating mutation of Fms-like tyrosine kinase 3 (FLT3) is the most frequent genetic alteration associated with poor prognosis in acute myeloid leukemia (AML). Although many FLT3 inhibitors have been clinically developed, no first-generation inhibitors have demonstrated clinical efficacy by monotherapy, due to poor pharmacokinetics or unfavorable safety profiles possibly associated with low selectivity against FLT3 kinase. Recently, a selective FLT3 inhibitor, quizartinib, demonstrated favorable outcomes in clinical studies. However, several resistant mutations emerged during the disease progression. To overcome these problems, we developed a novel FLT3 inhibitor, FF-10101, designed to possess selective and irreversible FLT3 inhibition. The co-crystal structure of FLT3 protein bound to FF-10101 revealed the formation of a covalent bond between FF-10101 and the cysteine residue at 695 of FLT3. The unique binding brought high selectivity and inhibitory activity against FLT3 kinase. FF-10101 showed potent growth inhibitory effects on human AML cell lines harboring FLT3 internal tandem duplication (FLT3-ITD), MOLM-13, MOLM-14, and MV4-11, and all tested types of mutant FLT3-expressing 32D cells including quizartinib-resistant mutations at D835, Y842, and F691 residues in the FLT3 kinase domain. In mouse subcutaneous implantation models, orally administered FF-10101 showed significant growth inhibitory effect on FLT3-ITD-D835Y- and FLT3-ITD-F691L-expressing 32D cells. Furthermore, FF-10101 potently inhibited growth of primary AML cells harboring either FLT3-ITD or FLT3-D835 mutation in vitro and in vivo. These results indicate that FF-10101 is a promising agent for the treatment of patients with AML with FLT3 mutations, including the activation loop mutations clinically identified as quizartinib-resistant mutations.

Application of Monoclonal Antibodies Against Mouse Dermokine.

Dermokine is one of the most highly expressed proteins in differentiating keratinocytes. Mouse dermokine has been reported to be encoded by 22 exons, and its expression leads to three transcripts, ß, γ, and α, which are transcribed from two different transcriptional start sites. The α isoform represents the carboxyl-terminal domain of the ß isoform, whereas the γ isoform lacks this domain. To reveal the distributions and expression levels of each isoform in mice, we generated rat monoclonal antibodies against dermokine-ß/γ and dermokine-ß/α. In immunofluorescence studies, the expression levels of dermokine in the cytosol of the cultured mouse keratinocytes were significantly elevated by high levels of extracellular calcium. In Western blot analyses, the expression levels of dermokine-ß and dermokine-α were increased in the presence of high calcium. Finally, we developed a monoclonal antibody-based sensitive sandwich enzyme-linked immunosorbent assay (ELISA) and showed that the secreted dermokine-ß into the culture medium from mouse keratinocytes was significantly increased in a manner dependent on the extracellular calcium concentration. These dermokine-specific antibodies have allowed us to gain new insights into the role of each dermokine isoform in cutaneous homeostasis.

Analysis of 62 synthetic cannabinoids by gas chromatography-mass spectrometry with photoionization.

Gas chromatography-mass spectrometry (GC-MS) in electron ionization (EI) mode is one of the most commonly used techniques for analysis of synthetic cannabinoids, because the GC-EI-MS spectra contain characteristic fragment ions for identification of a compound; however, the information on its molecular ions is frequently lacking. To obtain such molecular ion information, GC-MS in chemical ionization (CI) mode is frequently used. However, GC-CI-MS requires a relatively tedious process using reagent gas such as methane or isobutane. In this study, we show that GC-MS in photoionization (PI) mode provided molecular ions in all spectra of 62 synthetic cannabinoids, and 35 of the 62 compounds showed only the molecular radical cations. Except for the 35 compounds, the PI spectra showed very simple patterns with the molecular peak plus only a few fragment peak(s). An advantage is that the ion source for GC-PI-MS can easily be used for GC-EI-MS as well. Therefore, GC-EI/PI-MS will be a useful tool for the identification of synthetic cannabinoids contained in a dubious product. To the best of our knowledge, this is the first report to use GC-PI-MS for analysis of synthetic cannabinoids.

Novel phototoxicity assay using human embryonic stem cell-derived retinal pigment epithelial cells.

Some chemicals are harmful in to light-exposed tissues such as skin and eyes. The 3T3 Neutral Red Uptake Phototoxicity Test has been validated and adopted by the Organization of Economic and Community Development (OECD) as a method of evaluating chemical phototoxicity using mouse 3T3 fibroblasts. However, the high rate of false positive results associated with this test eventually led to increased laboratory animal usage. Although the eye is vulnerable to light damage because of constant exposure to environmental radiation, few approaches are available to predict ocular phototoxicity in humans. Here, we propose a tier one test that identifies the potential ocular phototoxicity of chemical substances. Using a three-dimensional culture technique, human embryonic stem cells (hESCs) were differentiated to retinal pigment epithelial cell (RPE) precursors. The precursors after prolonged treatment with FBS formed a uniform hexagonal lattice of cells with well-developed tight junctions and time-dependent elevation of melanin content and RPE maturation marker levels. Hierarchical clustering of gene transcripts revealed that hESC-derived RPEs were very similar to tissue-derived adult RPEs. Interestingly, there were a high percentage of chemicals eliciting a positive response in 3T3 cells and negative in hESC-derived RPEs under the experimental conditions used in the phototoxicity test. The response to treatment of hESC-derived RPEs with these negative chemicals became positive at a higher dose of UVA irradiation; however, the biological responses to these chemicals differed between the two cells. Taken together, we conclude that hESC-derived RPEs are novel tool for future toxicological and mechanistic studies of ocular phototoxicity in humans.

Generation of Rat Monoclonal Antibodies Against Human Pancreatic Ductal Adenocarcinoma Cells.

Pancreatic ductal adenocarcinoma is an aggressive tumor with a poor prognosis. Biomarkers that can detect the tumor in its early stages when it may be amenable to curative resection might improve prognosis. To discover novel markers expressed in primary pancreatic cancer, we generated a panel of monoclonal antibodies against pancreatic ductal adenocarcinoma cell line BxPC3 using a rat medial iliac lymph node method. The antigen recognized by 1B5A5 was expressed on the cell surface and secreted into the conditioned medium of BxPC3 cells, and characterized as glycoproteins with molecular mass between 60 and 90 kDa. A wide range of molecular weights of 1B5A5 antigen in several pancreatic cancer cell lines were observed. Immunohistochemistry using a human multiple organ tumor tissue array showed an enhanced expression of 1B5A5 antigen in pancreas, lung, stomach, breast, urinary bladder, colon, and cervix uteri cancers. Immunoprecipitation followed by proteomic analyses identified CEACAM6 as a 1B5A5 antigen. In addition, western blot analysis results indicated that the 1B5A5 epitope is located within an amino-terminal domain of CEACAM6. These results raised the possibility that our approach could lead to discovery of novel biomarkers for the early stage of cancers in a relatively short period of time.

An improved model of predicting hepatocarcinogenic potential in rats by using gene expression data.

Carcinogenicity studies using animals are expensive and time consuming. Therefore, the development of a highly accurate carcinogenicity prediction system to interpret short-term test results would be beneficial. The Ames test is popular for mutagens; however, it cannot detect non-genotoxic carcinogens. Previously, we reported a prediction system using gene expression data obtained from a short-term (28-day) study that screened candidate compounds for testing in long-term carcinogenicity studies. In this study, our system was improved by adding more gene expression data. To establish our new system, we used the data of 93 test compounds (41 hepatocarcinogens and 52 non-hepatocarcinogens). Analysis of liver gene expression data by dividing compounds into 'for training' and 'for test' categories (20 cases assigned randomly) using Support Vector Machine (SVM) identified a set of marker probe sets that could be used to predict hepatocarcinogenicity. The assigned 42 probe sets have included the cancer- or c-Myc-related genes such as Hsp90, Pink1, Hspc111, Fbx29, Hepsin, Syndecan2 and Synbindin. Compared with the older version, the improved system had a higher concordance rate with the training data and a good performance with the external test data.

Transplantation of human embryonic stem cell-derived retinal tissue in two primate models of retinal degeneration.

Retinal transplantation therapy for retinitis pigmentosa is increasingly of interest due to accumulating evidence of transplantation efficacy from animal studies and development of techniques for the differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells into retinal tissues or cells. In this study, we aimed to assess the potential clinical utility of hESC-derived retinal tissues (hESC-retina) using newly developed primate models of retinal degeneration to obtain preparatory information regarding the potential clinical utility of these hESC-retinas in transplantation therapy. hESC-retinas were first transplanted subretinally into nude rats with or without retinal degeneration to confirm their competency as a graft to mature to form highly specified outer segment structure and to integrate after transplantation. Two focal selective photoreceptor degeneration models were then developed in monkeys by subretinal injection of cobalt chloride or 577-nm optically pumped semiconductor laser photocoagulation. The utility of the developed models and a practicality of visual acuity test developed for monkeys were evaluated. Finally, feasibility of hESC-retina transplantation was assessed in the developed monkey models under practical surgical procedure and postoperational examinations. Grafted hESC-retina was observed differentiating into a range of retinal cell types, including rod and cone photoreceptors that developed structured outer nuclear layers after transplantation. Further, immunohistochemical analyses suggested the formation of host-graft synaptic connections. The findings of this study demonstrate the clinical feasibility of hESC-retina transplantation and provide the practical tools for the optimization of transplantation strategies for future clinical applications.

Optimal dose selection of N-methyl-N-nitrosourea for the rat comet assay to evaluate DNA damage in organs with different susceptibility to cytotoxicity.

The in vivo rodent alkaline comet assay (comet assay) is a promising technique to evaluate DNA damage in vivo. However, there is no agreement on a method to evaluate DNA damage in organs where cytotoxicity is observed. As a part of the Japanese Center for the Validation of Alternative Methods (JaCVAM)-initiative international validation study of the comet assay, we examined DNA damage in the liver, stomach, and bone marrow of rats given three oral doses of N-methyl-N-nitrosourea (MNU) up to the maximum tolerated dose based on systemic toxicity. MNU significantly increased the % tail DNA in all the organs. Histopathological analysis showed no cytotoxic effect on the liver, indicating clearly that MNU has a genotoxic potential in the liver. In the stomach, however, the cytotoxic effects were very severe at systemically non-toxic doses. Low-dose MNU significantly increased the % tail DNA even at a non-cytotoxic dose, indicating that MNU has a genotoxic potential also in the stomach. Part of the DNA damage at cytotoxic doses was considered to be a secondary effect of severe cell damage. In the bone marrow, both the % tail DNA and incidence of micronucleated polychromatic erythrocytes significantly increased at non-hematotoxic doses, which were different from the non-cytotoxic doses for liver and stomach. These findings indicate that an optimal dose for detecting DNA damage may vary among organs and that careful attention is required to select an optimum dose for the comet assay based on systemic toxicity such as mortality and clinical observations. The present study shows that when serious cytotoxicity is suggested by increased % hedgehogs in the comet assay, histopathological examination should be included for the evaluation of a positive response.

Genotoxicity evaluation of benzene, di(2-ethylhexyl) phthalate, and trisodium ethylenediamine tetraacetic acid monohydrate using a combined rat comet/micronucleus assays.

As a part of the Japanese Center for the Validation of Alternative Methods (JaCVAM)-initiative international validation study of the in vivo alkaline comet assay (comet assay), we examined DNA damage in the liver, stomach, and bone marrow of rats dosed orally three times with up to 2000 mg/kg of benzene, di(2-ethylhexyl) phthalate, and trisodium ethylenediamine tetraacetic acid monohydrate. All three compounds gave negative results in the liver and stomach. In addition, a bone marrow comet and micronucleus analysis revealed that benzene, but not di(2-ethylhexyl) phthalate or trisodium ethylenediamine tetraacetic acid monohydrate induced a significant increase in the median % tail DNA and micronucleated polychromatic erythrocytes, compared with the respective concurrent vehicle control. These results were in good agreement with the previously reported genotoxicity findings for each compound. The present study has shown that combining the micronucleus test with the comet assay and carrying out these analyses simultaneously is effective in clarifying the mechanism of action of genotoxic compounds such as benzene.