Published papers

Background/Aims: Thromboprophylaxis is recommended for hospitalized patients with inflammatory bowel disease (IBD) in Western countries, although it is selectively administered to high-risk patients in East Asia. A central venous catheter (CVC) is commonly placed in patients with IBD. Although CVC placement is considered a risk factor for venous thromboembolism (VTE), the degree of increased risk in patients with IBD is uncertain. This study aimed to identify the risk of VTE with CVC placement in hospitalized Japanese patients with IBD without thromboprophylaxis. Methods: This retrospective cohort study included patients with ulcerative colitis or Crohn’s disease who were admitted for disease flares at Keio University Hospital between January 2016 and December 2020. Patients who already had thrombosis or were administered any antithrombotic treatment on admission were excluded. VTE development during the hospitalization was surveyed, and VTE risk associated with CVC indwelling was estimated using propensity score matching and inverse probability of treatment weighting analyses. Results: Altogether, 497 hospitalized patients with IBD (ulcerative colitis, 327; Crohn’s disease, 170) were enrolled. VTE developed in 9.30% (12/129) of catheterized patients and in 0.82% (3/368) of non-catheterized patients. The propensity score matching yielded 127 matched pairs of patients. The catheterized group demonstrated higher odds for VTE than the non-catheterized group (odds ratio, 13.15; 95% confidence interval, 1.68–102.70). A similar result was obtained in the inverse probability of treatment weighting analysis (odds ratio, 11.02; 95% confidence interval, 2.64–46.10). Conclusions: CVC placement is a major risk factor for VTE among hospitalized Japanese patients with IBD without thromboprophylaxis.

Short bowel syndrome (SBS) is a rare condition, the main symptom of which is malabsorption following extensive resection of the small intestine. Treatment for SBS is mainly supportive, consisting of supplementation, prevention and treatment of complications, and promotion of intestinal adaptation. While development of parenteral nutrition and drugs promoting intestinal adaptation has improved clinical outcomes, the prognosis of patients with SBS remains poor. Intestinal transplantation is the only curative therapy but its outcome is unsatisfactory. In the absence of definitive therapy, novel treatment is urgently needed. With the advent of intestinal organoids, research on the intestine has developed remarkably in recent years. Concepts such as the “tissue-engineered small intestine” and “small intestinalized colon,” which create a functional small intestine by combining organoids with other technologies, are potentially novel regenerative therapeutic approaches for SBS. Although they are still under development and there are substantial issues to be resolved, the problems that have prevented establishment of the complex function and structure of the small intestine are gradually being overcome. This review discusses the current treatments for SBS, the fundamentals of the intestine and organoids, the current status of these new technologies, and future perspectives.

The sigmoid colon tends to form loops and bends easily and is therefore considered a difficult site for colonoscope insertion. Inexperienced trainees may accidentally dilate the sigmoid colon following excessive air insufflation, and colonoscope insertion is challenging in such cases even with the use of the axis-retaining shortening method. The water infusion method developed in Japan involves injection of a small amount of water, which facilitates shortening and straightening. The collapse-submergence method, which includes a combination of degassing at the sigmoid colon and the water infusion method, is an improved technique that eliminates the water-air interface to provide a better field of view. The water immersion method can be easily learned even by trainees and is shown to improve the cecal intubation rate and suppress loop formation, which minimizes patient discomfort. This method is also utilized to perform detorsion of sigmoid volvulus and evaluation of irritable bowel syndrome and intestinal morphological abnormalities. Water-aided colonoscopy is popular in the U.S. and Europe, and studies have reported improved adenoma detection rates using “water exchange.” This innovative method is not only useful for endoscope insertion but also aids with underwater endoscopic mucosal resection. Water infusion-related techniques put to advantage the characteristics of water and overcome the limitations encountered with air insufflation methods and are expected to become increasingly popular in the future.

OBJECTIVE: Crohn's disease (CD) is a chronic inflammatory gastrointestinal disease with repeated cycles of exacerbation and remission. Infliximab (IFX), a chimeric anti-TNF-α monoclonal antibody, has been widely used for the treatment of CD. However, no study in Japanese CD patients receiving continuous IFX for more than 1 year has been reported. To avoid therapeutic failure during long-term administration in Japanese CD patients, we evaluated the variable factors of IFX pharmacokinetics and the optimal trough IFX concentration at 8 weeks after administration. MATERIALS AND METHODS: Population pharmacokinetic (PPK) analysis was performed using the nonlinear mixed-effect model based on the IFX serum concentration in 832 samples from 121 patients. A one-compartment model was used to examine interindividual variability in the systemic clearance (CL) of intravenously administered IFX. RESULTS: PPK estimates (estimated value, RSE%) were total clearance (CL: 0.018 L/h, 9.1) and volumes of distribution (Vd: 7.35 L, 12.0). Interindividual variability for CL and Vd of 0.11 and 0.16, respectively, was found. Body weight, antibody to IFX (ATI), and albumin level were factors affecting the IFX CL. IFX CL was greater in the ATI-positive than in the ATI-negative group. CL was also greater in nonremission patients. There was a significant association between the predicted serum IFX trough concentration at 8 weeks and therapeutic response with long-term continuous administration (p < 0.05), with a higher concentration at 8 weeks seen in the remission group. CONCLUSION: Using these variables including body weight, ATI, and albumin level, the IFX dose could be calculated for individual CD patients to achieve the optimal therapeutic range.

© 2020 AGA Institute Background & Aims: We compared the diagnostic accuracy of the fecal calprotectin (FCP) test vs the fecal immunochemical blood test (FIT) in determining the endoscopic severity and predicting outcomes of patients with ulcerative colitis (UC). Methods: We performed a nationwide study of 879 patients with UC, enrolled at medical centers across Japan, from March 2015 to March 2017. We collected data on fecal biomarkers, endoscopic severities, and other clinical indices from Cohort 1 (n = 427) and assessed the diagnostic accuracy of FCP measurement and FIT results in determining clinical severity, based on Mayo score, and endoscopic remission, based on Mayo endoscopic sub-score (MES) or UC endoscopic index of severity. We also followed 452 patients in clinical remission from UC (Cohort 2) for 12 months and evaluated the associations of FCP levels and FIT results with clinical recurrence. Results: The levels of FCP and FIT each correlated with the MES and UC endoscopic index of severity. There were no significant differences in the areas under the curve of FCP vs FIT in distinguishing patients with MES≤1 from those with MES≥2 (P = .394) or in distinguishing patients with MES=0 from those with MES≥1 (P = .178). Among 405 patients in clinical remission at baseline, 38 (9.4%) had UC recurrences within 3 months and 90 (22.2%) had recurrences within 12 months. FCP≥146 mg/kg (hazard ratio [HR], 4.83; 95% confidence interval [CI], 2.80-8.33) and FIT≥77 ng/mL (HR, 2.92; 95% CI, 1.76-4.83) were independently associated with clinical recurrence within 12 months. UC recurred within 12 months in 69% of patients with levels of FCP≥146 mg/kg and FIT ≥77 ng/mL; this value was significantly higher than the rate of recurrence in patients with levels of FCP≥146 mg/kg and FIT <77 ng/mL (31.5%, P < .001) or patients with levels of FCP<146 mg/kg and FIT ≥77 ng/mL (30.0%, P < .001). Conclusion: In a nationwide study of patients with UC in Japan, we found that the level of FCP and FIT could each identify patients with endoscopic markers of disease severity (MES≥2). The combination of FCP and FIT results can identify patients in remission who are at risk for disease recurrence. Clinical Trials Registry no: UMIN000017650 (http://www.umin.ac.jp/ctr/)

© 2018 Elsevier Inc. Recent sequencing analyses have shed light on heterogeneous patterns of genomic aberrations in human gastric cancers (GCs). To explore how individual genetic events translate into cancer phenotypes, we established a biological library consisting of genetically engineered gastric organoids carrying various GC mutations and 37 patient-derived organoid lines, including rare genomically stable GCs. Phenotype analyses of GC organoids revealed divergent genetic and epigenetic routes to gain Wnt and R-spondin niche independency. An unbiased phenotype-based genetic screening identified a significant association between CDH1/TP53 compound mutations and the R-spondin independency that was functionally validated by CRISPR-based knockout. Xenografting of GC organoids further established the feasibility of Wnt-targeting therapy for Wnt-dependent GCs. Our results collectively demonstrate that multifaceted genetic abnormalities render human GCs independent of the stem cell niche and highlight the validity of the genotype-phenotype screening strategy in gaining deeper understanding of human cancers. Generation and analysis of a human gastric cancer organoid bank reveal insights into molecular features underlying diverse histopathological subtypes and tumor independence from Wnt signals.

© 2018 AGA Institute Background & Aims: Indigo naturalis (IN) is a traditional Chinese medicine that contains ligands for the aryl hydrocarbon receptor and promotes regeneration of the mucosa by inducing production of interleukin 22. IN might induce mucosal healing in patients with ulcerative colitis (UC). We performed a randomized controlled trial to investigate the safety and efficacy of IN in patients with UC. Methods: We performed a multicenter, double-blind trial evaluating the safety of 86 patients in Japan with active UC (Mayo scores of 6 or more), enrolled from March 30 through December 27, 2016. Patients were randomly assigned to groups and given a daily dose of 0.5, 1.0, or 2.0 g IN or placebo (1:1:1:1 ratio) for 8 weeks. The primary endpoint was the rate of clinical response at week 8, defined as a 3-point decrease in the Mayo score and a decrease of at least 30% from baseline, with a decrease of at least 1 point for the rectal bleeding subscore or absolute rectal bleeding score of 0–1. The main secondary endpoint was the rate of clinical remission at week 8, defined as a Mayo score or ≤2 and no subscores with a value >1. Mucosal healing was also assessed at week 8. Results: The trial was terminated because of an external reason: a report of pulmonary arterial hypertension in a patient who used self-purchased IN for 6 months. In the intent-to-treat analysis, we observed a significant, dose-dependent linear trend in proportions of patients with clinical responses (13.6% with a clinical response to placebo; 69.6% to 0.5 g IN; 75.0% to 1.0 g IN; and 81.0% to 2.0 g IN) (Cochran-Armitage trend test P <.0001 compared with placebo). Proportions of patients in clinical remission at week 8 were significantly higher in the 1.0 g IN group (55.0%, P =.0004) and the 2.0 g IN group (38.1%, (P =.0093) than in the placebo group (4.5%). Proportions of patients with mucosal healing were 13.6% in the placebo group, 56.5% in the 0.5 g IN group, 60.0% in the 1.0 g IN group, and 47.6% in the 2.0 g IN group (P =.0278 compared with placebo). Although mild liver dysfunction was observed in 10 patients who received IN, no serious adverse events were observed. Conclusions: In a randomized, placebo-controlled trial, we found 8 weeks of IN (0.5–2.0 g per day) to be effective in inducing a clinical response in patients with UC. However, IN should not yet be used because of the potential for adverse effects, including pulmonary arterial hypertension. Clinical Trials Registry no: UMIN000021439 (http://www.umin.ac.jp/ctr/).

© 2018 Crohn's & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions. Background Mucosal healing (MH) is proposed as a therapeutic target for ulcerative colitis (UC). Recent studies have indicated that the rate of clinical relapse in patients with a Mayo endoscopic score (MES) of 1 is higher than that of patients with an MES of 0. However, no study has yet investigated whether therapeutic intervention prevents clinical relapse in patients with an MES of 1. Methods Patients with UC with an MES of 1 and partial Mayo score ≤2 were included in this study. All patients were followed from first colonoscopy (CS) until follow-up CS. Differences in the rate of clinical relapse (requiring additional treatment for UC) or endoscopic exacerbation (MES ≥2 and proximal extension) were compared between the therapeutic intervention (immediately after first CS) group and the nontherapeutic intervention group; risk factors for relapse were also assessed. Results Among 1523 patients with UC who underwent CS between 2013 and 2016, 220 patients were included in this study. The rate of clinical relapse (P = 0.005) and endoscopic exacerbation (P = 0.11) in patients with therapeutic intervention was lower than that in patients without therapeutic intervention. Multivariable analysis indicated that absence of therapeutic intervention (P = 0.001 for clinical relapse, P = 0.050 for endoscopic exacerbation) and a higher Ulcerative Colitis Endoscopic Index of Severity vascular pattern score immediately after first CS (P = 0.021 for clinical relapse, P = 0.019 for endoscopic exacerbation) were risk factors for both clinical relapse and endoscopic exacerbation. Conclusions Therapeutic intervention for patients with UC with an MES of 1 might prevent disease relapse.

© 2018. Korean Association for the Study of Intestinal Diseases. Fecal microbiota transplantation (FMT) has been reported as a safe and effective therapy in patients with refractory and recurrent Clostridium difficile infection (CDI). FMT has also been reported as a promising therapy in patients with ulcerative colitis (UC). Both, CDI and UC, are believed to be caused by dysbiosis, such as altered compositions or decreased diversity of the intestinal microbiota. This report describes a patient with UC in remission with a second recurrent episode of CDI, who was treated with FMT. A single FMT performed via colonoscopy completely resolved the patient's diarrhea and eradicated C. difficile bacteriologically without any severe complications. Molecular biological analysis of the patient's fecal microbiota showed that FMT could dramatically change the altered composition of intestinal microbiota and restore its diversity. Despite the restoration of the intestinal microbiota, FMT could not prevent a relapse of UC in this patient. However, it improved the intestinal symptoms of CDI and could prevent further recurrences of CDI.

© 2018 Elsevier Inc. Cellular diversity that shapes tissue architecture and function is governed by multiple niche signals. Nonetheless, maintaining cellular diversity in human intestinal organoids has been challenging. Based on niche ligands present in the natural stem cell milieu, we establish a refined organoid culture condition for intestinal epithelia that allows human intestinal organoids to concurrently undergo multi-differentiation and self-renewal. High-throughput screening reveals that the combination of insulin-like growth factor 1 (IGF-1) and fibroblast growth factor 2 (FGF-2) enhances the clonogenic capacity and CRISPR-genome engineering efficiency of human intestinal stem cells. The combination equally enables long-term culture of a range of intestinal organoids, including rat small intestinal organoids. Droplet-based single-cell RNA sequencing further illustrates the conservation of the native cellular diversity in human small intestinal organoids cultured with the refined condition. The modified culture protocol outperforms the conventional method and offers a viable strategy for modeling human intestinal tissues and diseases in an in vivo relevant context. Sato and colleagues develop a modified culture condition for human intestinal organoids that improves the culture efficiency and maintains their long-term multi-differentiation capacity. scRNA-seq of human small intestinal crypts and organoids demonstrates that in vivo cellular diversity can be preserved in organoids cultured with the refined condition.

© 2017 Elsevier Inc. Despite recent efforts to dissect the inter-tumor heterogeneity of pancreatic ductal adenocarcinoma (PDAC) by determining prognosis-predictive gene expression signatures for specific subtypes, their functional differences remain elusive. Here, we established a pancreatic tumor organoid library encompassing 39 patient-derived PDACs and identified 3 functional subtypes based on their stem cell niche factor dependencies on Wnt and R-spondin. A Wnt-non-producing subtype required Wnt from cancer-associated fibroblasts, whereas a Wnt-producing subtype autonomously secreted Wnt ligands and an R-spondin-independent subtype grew in the absence of Wnt and R-spondin. Transcriptome analysis of PDAC organoids revealed gene-expression signatures that associated Wnt niche subtypes with GATA6-dependent gene expression subtypes, which were functionally supported by genetic perturbation of GATA6. Furthermore, CRISPR-Cas9-based genome editing of PDAC driver genes (KRAS, CDKN2A, SMAD4, and TP53) demonstrated non-genetic acquisition of Wnt niche independence during pancreas tumorigenesis. Collectively, our results reveal functional heterogeneity of Wnt niche independency in PDAC that is non-genetically formed through tumor progression. Sato and colleagues established a library of patient-derived pancreas cancer organoids and identified heterogeneous patterns of dependency on Wnt ligands among pancreas cancers. Biological and genetic analyses highlighted GATA6 as a mediator of the Wnt niche requirement, which links pancreatic tumor progression to independence from the stem cell niche.

© 2019 S. Karger AG, Basel. All rights reserved. Background: Indigo naturalis (IN) consists of ligands for the aryl hydrocarbon receptor and exhibits anti-inflammatory effects. Previously, we demonstrated that an 8-week treatment with oral IN is effective in inducing a clinical response in patients with ulcerative colitis (UC). Some UC patients with proctitis are refractory to topical mesalamine or corticosteroids and therefore require an alternative topical treatment. Objectives: We aimed to prospectively evaluate the safety and efficacy of IN suppositories in UC patients. Method: We performed an open-label, single-center, prospective pilot study from February 2018 to October 2018. A total of 10 patients with active UC, who had moderate to severe inflammation from the rectum to the sigmoid colon, were enrolled. The patients received a daily dose of 50 mg IN suppository for 4 weeks. The primary endpoint was safety at week 4. Results: Although 1 patient experienced anal pain, no serious adverse events were observed. At week 4, the rates of clinical remission and mucosal healing were 30 and 40%, respectively. Mayo rectal bleeding subscores significantly improved after treatment (1.80 ± 0.13 vs. 0.90 ± 0.28; p = 0.009). Approximately 80% of the patients with a baseline Mayo endoscopic subscore in the rectum (r-MES) of 2 achieved mucosal healing, but those with a baseline r-MES of 3 did not. Conclusions: We found that 4 weeks of IN suppository can be tolerated by UC patients, but its efficacy was limited by the severity of the disease. Further investigation will be needed in order to confirm the optimum dose of IN suppository for patients with UC.

© 2019 Editrice Gastroenterologica Italiana S.r.l. Background: Although various studies have been conducted on colitis-associated cancer (CAC), few have assessed the differences in the clinical and endoscopic features, treatment, and prognosis of CAC and sporadic neoplasia (SN) in the inflamed mucosa of ulcerative colitis (UC) patients. Aims: To compare the characteristics of CAC and SN within the previously or currently inflamed mucosa. Methods: Between 1997 and 2017, we retrospectively analyzed the endoscopic chart data of 348 colonic lesions from 266 UC patients. Non-dysplastic lesions and lesions located outside the inflamed mucosa were excluded. The diagnosis of CAC or SN was confirmed by conventional histopathological and immunohistochemical evaluation of p53 and Ki67. Results: In total, 74 patients with CAC (97 lesions) and 46 with SN (58) were enrolled. The proportions of patients with a younger age of onset of UC, with chronic persistent UC, and with severe inflamed mucosa were significantly higher in the CAC group. In the SN group, no flat lesions were found, whereas 26% of the lesions in the CAC group were flat. Sixteen patients died during a median follow-up of 6.1 years (interquartile range (IQR) 1.8–11.1)in the CAC group, whereas 1 patient died during a median follow-up 3.2 years(IQR 1.4–4.6) in the SN group. Mortality from colorectal cancer was significantly higher (P = 0.015) in the CAC group (12/68; 17.6%) than in the SN group (1/44; 2.3%). The 5-year survival rate was 100% in the SN group and 97% in the CAC group for lesions located in the mucosa or submucosa. Conclusion: Recognizing differences in the characteristics of CAC and SN within the inflamed mucosa is critical to avoid unnecessary total colectomy in patients with SN.

© 2019, Japanese Society of Gastroenterology. Background: We recently reported the efficacy of indigo naturalis (IN) in patients with active ulcerative colitis (UC) in a randomized controlled trial (INDIGO study). However, few studies have been conducted to investigate whether IN is effective even in treatment-refractory cases, such as in those with steroid dependency and anti-TNF refractoriness. Methods: In the INDIGO study, 86 patients with active UC were randomly assigned to an IN group (0.5–2.0 g daily) or placebo group. The rate of clinical response (CR), mucosal healing (MH), and change in fecal calprotectin (FCP) levels was compared between refractory [patients with steroid-dependent disease, previous use of anti-TNF-α, and concomitant use of immunomodulators (IM)] and non-refractory patients. We also analyzed factors predicting CR and MH at week 8. Results: The rates of CR of IN group were significantly higher than placebo group, even in patients with steroid-dependent disease (p < 0.001), previous use of anti-TNF-α (p = 0.002), and concomitant use of IM (p = 0.013). The rates of MH in IN group were significantly higher than in placebo group in patients with steroid-dependent disease (p = 0.009). In the IN group, median FCP levels, at week 8, were significantly lower than baseline in patients with steroid-dependent disease and patients with the previous use of anti-TNF-α (p < 0.001, respectively). Multivariate analysis indicated that the previous use of anti-TNF-α was not a predictive factor for CR and MH at week 8. Conclusions: In a sub-analysis of data from a randomized placebo-controlled trial, we found that IN may be useful even in patients with steroid-dependent disease and patients with the previous use of anti-TNF-α.

© 2019 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association. The incidence of colorectal cancer (CRC) has been on the rise, which is linked to the increasing prevalence of obesity, based on global epidemiological evidence. Although chronic inflammation is implicated in tumor development, the mechanisms underlying obesity-associated CRC remain unknown. Here, we sought to identify the inflammatory cytokines and their roles in obesity-related colorectal tumorigenesis using cytokine array analyses in a mouse model. Colorectal tumorigenesis was induced through i.p. injection of azoxymethane once a week for 6 weeks in 6-week-old female WT C57Black/6J mice and the obesity diabetes model mouse KK/TaJcl, KK-Ay/TaJcl. The formation of aberrant crypt foci and colorectal tumors were more frequent in obese mice compared with WT mice, and both serum interleukin (IL)-13 and IL-13 receptor (R) expression in the normal intestinal mucosal epithelium were significantly increased in the obese mice. Furthermore, addition of IL-13 to a human CRC cell line and a human colon organoid culture altered the phenotype of intestinal epithelial cells. Knockdown experiments further revealed that IL-13Rα1 dominantly induced mucosal proliferation. Collectively, These results suggest an association between anti-inflammatory cytokines and colorectal carcinogenesis, and provide new research directions for cancer prevention strategies. In particular, inflammation provoked by obesity, notably by increased expression of the cytokine IL-13, could play an important role in the carcinogenesis of obesity-related CRC.

© 2019 Japan Gastroenterological Endoscopy Society Despite the rarity of colorectal poorly differentiated adenocarcinoma (Por) and signet-ring cell carcinoma (Sig), they are more frequent in patients with ulcerative colitis (UC). However, little is known about these components of early colitis-associated cancer due to the difficulty of detection at an early stage. Here, we reviewed colitis-associated high-grade dysplasia/cancer with Por/Sig components within the submucosa among 103 lesions of 79 UC patients who presented between 1997 and 2017. In total, one Sig in situ, three intramucosal and two submucosal carcinomas (8.7%) were identified among 69 lesions within the submucosa. Depressed appearance, loss of crypt architecture and amorphous surface pattern suggested the presence of Por/Sig, rather than submucosal infiltration. All lesions were located in the rectosigmoid colon and included high-grade dysplasia. While the surrounding noncancerous mucosa expressed E-cadherin and MUC5AC, the expression of E-cadherin was reduced and the expression of MUC5AC was negative in all of the carcinomas except for the Sig in situ. The gastric type metaplasia associated with altered MUC5AC profiles may be a sign of the stepwise accumulation of molecular alterations, including TP53 defects and a reduced expression level of E-cadherin.

© 2020 Elsevier Inc. Gastroenteropancreatic (GEP) neuroendocrine neoplasm (NEN) that consists of neuroendocrine tumor and neuroendocrine carcinoma (NEC) is a lethal but under-investigated disease owing to its rarity. To fill the scarcity of clinically relevant models of GEP-NEN, we here established 25 lines of NEN organoids and performed their comprehensive molecular characterization. GEP-NEN organoids recapitulated pathohistological and functional phenotypes of the original tumors. Whole-genome sequencing revealed frequent genetic alterations in TP53 and RB1 in GEP-NECs, and characteristic chromosome-wide loss of heterozygosity in GEP-NENs. Transcriptome analysis identified molecular subtypes that are distinguished by the expression of distinct transcription factors. GEP-NEN organoids gained independence from the stem cell niche irrespective of genetic mutations. Compound knockout of TP53 and RB1, together with overexpression of key transcription factors, conferred on the normal colonic epithelium phenotypes that are compatible with GEP-NEN biology. Altogether, our study not only provides genetic understanding of GEP-NEN, but also connects its genetics and biological phenotypes. Gastroenteropancreatic neuroendocrine neoplasms are a rare but lethal cancer with a scarcity of clinically relevant models. Kawasaki et al. establish and characterize 25 organoid lines to identify molecular subtypes with genotype-phenotype mapping.

Our understanding of the biology of the intestinal epithelium has advanced since the establishment of an organoid culture system. Although organoids have enabled investigation of the mechanism of self-renewal of human intestinal stem cells in vitro, it remains difficult to clarify the behavior of human normal and diseased intestinal epithelium in vivo. Recently, we developed a xenotransplantation system in which human intestinal organoids are engrafted onto epithelium-depleted mouse colons. This xenograft recapitulated the original tissue structures. Upon xenotransplantation, normal colon organoids developed normal colon crypt structures without tumorigenesis, whereas tumor-derived organoids formed colonic tumors resembling the original tumors. The non-tumorigenicity of human intestinal organoids highlights the safety of organoid-based regenerative medicine. As an example of regenerative medicine for short bowel syndrome, we devised a unique organ-repurposing approach to convert colons into small intestines by organoid transplantation. In this approach, the transplanted rat small intestinal organ-oids not only engrafted onto the rat colons but also remodeled the colon subepithelial structures into a small intestine-like conformation. Luminal flow accelerated the maturation of villi in the small intes-tine, which promoted the formation of a lymphovascular network mimicking lacteals. In this review, we provide an overview of recent advances in gastrointestinal organoid transplantation and share our understanding of human disease biology and regenerative medicine derived from these studies.

© 2019, Japanese Society of Gastroenterology. Background: Although indigo naturalis (IN) is effective for patients with active ulcerative colitis (UC), IN was associated with adverse events (AEs), including pulmonary arterial hypertension (PAH). Our aim was to evaluate the occurrence of IN-associated AEs and to evaluate any IN dose–effect on AEs. Methods: A nationwide survey, using questionnaires, was conducted by conducted by the research group funded by the Ministry of Health, Labour and Welfare of Japan, between June 2017 and September 2018. A first questionnaire determined the occurrence of AEs associated with the therapeutic use of IN or herbal medicines containing IN in patients with UC. A second survey identified the clinical characteristics of patients who developed IN-associated critical AEs, namely, liver dysfunction, PAH, and intussusception. Results: Across 337 participating institutions, 49,320 patients with UC were identified, with IN used in 877 (1.8%). AEs were reported in 91 patients (107 events), including liver dysfunction (n = 40), gastrointestinal symptoms (n = 21), headache (n = 13), and PAH (n = 11). No dose–effect relationship between IN and AEs was identified. Liver dysfunction tended to be mild and reversible. Ten cases of intussusception were reported, with 40% of these patients requiring surgical resection. IN-induced PAH was recovered in patients who discontinued to use IN. No IN-associated deaths were reported. Conclusions: IN-associated AEs were identified among patients with UC, with liver dysfunction often being reversible, while surgical resection was required in a high proportion of patients who developed intussusception. Both healthcare workers and patients should adequately recognize the potential for AEs with the use of IN.