Colorectal adenoma detection rate using texture and color enhancement imaging versus white light imaging with chromoendoscopy: a propensity score matching study.

BACKGROUND AND AIM: Few studies have evaluated the adenoma detection rate (ADR) of colonoscopy with texture and color enhancement imaging (TXI), a novel image-enhancing technology. This study compares the detection of colorectal polyps using TXI to that using white light imaging (WLI). METHODS: This single-center retrospective study used propensity-matched scoring based on the patients' baseline characteristics (age, sex, indication, bowel preparation, endoscopist, colonoscope type, and withdrawal time) to compare the results of patients who underwent chromoendoscopy using WLI or TXI at the Toyoshima Endoscopy Clinic. The differences in polyp detection rates and the mean number of detected polyps per colonoscopy were determined between the TXI and WLI groups. RESULTS: After propensity score matching, 1970 patients were enrolled into each imaging modality group. The mean patient age was 57.2 ± 12.5 years, and 44.5% of the cohort were men. The ADR was higher in the TXI group than in the WLI group (55.0% vs 49.4%, odds ratio: 1.25). High-risk ADR were more common in the TXI group than in the WLI group (17.6% vs 12.8%; OR: 1.45). The mean number of adenomas per colonoscopy (APC) was higher in the TXI group than in the WLI group (1.187 vs 0.943, OR: 1.12). APC with a flat morphology (1.093 vs 0.848, OR: 1.14) and APC of <6 mm (0.992 vs 0.757, OR: 1.16) were higher in the TXI group than in the WLI group. CONCLUSION: Compared to WLI, TXI improved the ADR in patients who underwent chromoendoscopy based on actual clinical data.

Association between colonic adenoma size and proliferative zone in the crypt.

BACKGROUND: We previously reported unusual adenomas with proliferative zones confined to the lower two-thirds of the crypt. The proliferative zones of colorectal adenomas have three patterns: 'lower,' 'superficial' and 'entire'. This study aimed to clarify the characteristics of each adenoma pattern. METHODS: We investigated 2925 consecutive patients who underwent colonoscopy at our institute. All polyps that were removed were histologically examined using hematoxylin and eosin staining. The location of the proliferative zone was assessed for adenomas. Data were compared using Dunn's and Kruskal-Wallis tests. RESULTS: Colorectal adenomas with 'lower' proliferative zone often appeared similar to hyperplastic polyps (42.8%), and the frequency was significantly higher than that of adenomas with 'superficial' and 'entire' proliferative zones (p < 0.001). The mean sizes of adenomas were 2.4, 3.0 and 3.9 mm for 'lower,' 'superficial' and 'entire' proliferative zones, respectively. A significant gradual increase was observed. Regarding morphology, the proportion of type 0-I in adenomas with an 'entire' proliferative zone was significantly higher than that in adenomas with 'superficial' proliferative zone (p < 0.001). CONCLUSION: While colorectal adenomas develop and increase in size, the proliferative zone appears to shift upward and become scattered.

Hyperplastic polyp-like adenoma: a subtype of colonic adenoma with a proliferative zone confined to the lower two-thirds of the crypt.

BACKGROUND: The proliferative zone of colonic adenomas is confined to the upper third of the crypt or is scattered along its entire axis. In contrast, there are unusual adenomas with proliferative zones confined to the lower two-thirds of the crypt. We investigated the frequency and endoscopic features of adenomas with lower proliferative zones. METHODS: We retrospectively reviewed consecutive patients who underwent colonoscopies between September 2022 and March 2023 at the Toyoshima Endoscopy Clinic. Colorectal polyps were endoscopically assessed using the Japan Narrow-Band Imaging Expert Team (JNET) classification. All resected polyps were histologically examined, and the proliferative zone locations were assessed in the adenomas. RESULTS: The frequency of adenomas with a lower proliferative zone was 1.8% (44/2420) in adenomas. Among these adenomas, JNET type 1 incidence was 43.2% (19/44), which was significantly higher than that in adenomas with a normal proliferative zone. Adenomas with a lower proliferative zone were diminutive (mean size: 2.5 mm) and prone to develop in the proximal colon. CONCLUSION: Colonic adenomas with proliferative zones confined to the lower two-thirds of the crypt often appear as diminutive, hyperplastic polyps.

Gastric cancer incidence based on endoscopic Kyoto classification of gastritis.

BACKGROUND: Gastric cancer (GC) incidence based on the endoscopic Kyoto classification of gastritis has not been systematically investigated using time-to-event analysis. AIM: To examine GC incidence in an endoscopic surveillance cohort. METHODS: This study was retrospectively conducted at the Toyoshima Endoscopy Clinic. Patients who underwent two or more esophagogastroduodenoscopies were enrolled. GC incidence was based on Kyoto classification scores, such as atrophy, intestinal metaplasia (IM), enlarged folds (EFs), nodularity, diffuse redness (DR), and total Kyoto scores. Hazard ratios (HRs) adjusted for age and sex were calculated using a Cox hazard model. RESULTS: A total of 6718 patients were enrolled (median age 54.0 years; men 44.2%). During the follow-up period (max 5.02 years; median 2.56 years), GC developed in 34 patients. The average frequency of GCs per year was 0.19%. Kyoto atrophy scores 1 [HR with score 0 as reference: 3.66, 95% confidence interval (CI): 1.06 to 12.61], 2 (11.60, 3.82-35.27), IM score 2 (9.92, 4.37-22.54), EF score 1 (4.03, 1.63-9.96), DR scores 1 (6.22, 2.65-14.56), and 2 (10.01, 3.73-26.86) were associated with GC incidence, whereas nodularity scores were not. The total Kyoto scores of 4 (HR with total Kyoto scores 0-1 as reference: 6.23, 95%CI: 1.93 to 20.13, P = 0.002) and 5-8 (16.45, 6.29-43.03, P < 0.001) were more likely to develop GC, whereas the total Kyoto scores 2-3 were not. The HR of the total Kyoto score for developing GC per 1 rank was 1.75 (95%CI: 1.46 to 2.09, P < 0.001). CONCLUSION: A high total Kyoto score (≥ 4) was associated with GC incidence. The endoscopy-based diagnosis of gastritis can stratify GC risk.

Hemorrhoids as a risk factor for colorectal adenomas on colonoscopy.

Background and study aims Colorectal premalignant polyps and hemorrhoids are important findings in colonoscopy; however, the association between them is unclear. Therefore, we investigated the association between the presence and severity of hemorrhoids and the detection of precancerous colorectal polyps on colonoscopy. Patients and methods This retrospective, single-center, cross-sectional study enrolled patients who underwent colonoscopy at Toyoshima Endoscopy Clinic between May 2017 and October 2020. The association between hemorrhoids and other outcomes (patient age, sex, withdrawal time for colonoscopy, expert endoscopist, number of adenomas per colonoscopy, detection rates of adenoma, advanced neoplasia, clinically significant serrated polyp, and sessile serrated lesion) was assessed using a binomial logistic regression model. Results A total of 12,408 patients were enrolled in this study. Hemorrhoids were identified in 1,863 patients. Univariable analysis showed that patients with hemorrhoids were older (61.0 vs. 52.5 years, P  < 0.001), had a higher number of adenomas per colonoscopy (1.16 vs. 0.756, P  < 0.001) than those without hemorrhoids. Multivariable analyses also demonstrated that hemorrhoids were associated with a higher number of adenomas per colonoscopy (odds ratio [OR]: 1.061; P  = 0.002), regardless of patient age, sex, and expert endoscopist. Among patients with hemorrhoids, severe hemorrhoids with a mucosal elevation ≥ 10 mm were associated with a higher number of adenomas per colonoscopy than mild hemorrhoids (OR: 1.112, P  = 0.044), regardless of patient age, sex, and expert endoscopist. Conclusions Hemorrhoids, especially severe ones, are associated with a high number of adenomas. Complete colonoscopy should be performed in patients with hemorrhoids.

Improved visibility of colorectal tumor by texture and color enhancement imaging with indigo carmine.

BACKGROUND: Accurate diagnosis and early resection of colorectal polyps are important to prevent the occurrence of colorectal cancer. However, technical factors and morphological factors of polyps itself can lead to missed diagnoses. Image-enhanced endoscopy and chromoendoscopy (CE) have been developed to facilitate an accurate diagnosis. There have been no reports on visibility using a combination of texture and color enhancement imaging (TXI) and CE for colorectal tumors. AIM: To investigate the visibility of margins and surfaces with the combination of TXI and CE for colorectal lesions. METHODS: This retrospective study included patients who underwent lower gastrointestinal endoscopy at the Toyoshima Endoscopy Clinic. We extracted polyps that were resected and diagnosed as adenomas or serrated polyps (hyperplastic polyps and sessile serrated lesions) from our endoscopic database. An expert endoscopist performed the lower gastrointestinal endoscopies and observed the lesion using white light imaging (WLI), TXI, CE, and TXI + CE modalities. Indigo carmine dye was used for CE. Three expert endoscopists rated the visibility of the margin and surface patterns in four ranks, from 1 to 4. The primary outcomes were the average visibility scores for the margin and surface patterns based on the WLI, TXI, CE, and TXI + CE observations. Visibility scores between the four modalities were compared by the Kruskal-Wallis and Dunn tests. RESULTS: A total of 48 patients with 81 polyps were assessed. The histological subtypes included 50 tubular adenomas, 16 hyperplastic polyps, and 15 sessile serrated lesions. The visibility scores for the margins based on WLI, TXI, CE, and TXI + CE were 2.44 ± 0.93, 2.90 ± 0.93, 3.37 ± 0.74, and 3.75 ± 0.49, respectively. The visibility scores for the surface based on WLI, TXI, CE, and TXI + CE were 2.25 ± 0.80, 2.84 ± 0.84, 3.12 ± 0.72, and 3.51 ± 0.60, respectively. The visibility scores for the detection and surface on TXI were significantly lower than that on CE but higher than that on WLI (P < 0.001). The visibility scores for the margin and surface on TXI + CE were significantly higher than those on CE (P < 0.001). In the sub-analysis of adenomas, the visibility for the margin and surface on TXI + CE was significantly better than that on WLI, TXI, and CE (P < 0.001). In the sub-analysis of serrated polyps, the visibility for the margin and surface on TXI + CE was also significantly better than that on WLI, TXI, and CE (P < 0.001). CONCLUSION: TXI + CE enhanced the visibility of the margin and surface compared to WLI, TXI, and CE for colorectal lesions.

Impact of looping on premalignant polyp detection during colonoscopy.

BACKGROUND: The presence of premalignant polyps on colonoscopy is an indicator of metachronous colorectal cancer. Looping during colonoscopy is associated with old age, female sex, and colonoscopy insertion time. However, the clinical significance of looping is not fully understood. We aimed to clarify the effect of looping on colorectal premalignant polyp detection. AIM: To assess the effects of looping on premalignant polyp detection using logistic regression analyses. METHODS: We retrospectively investigated patients who underwent colonoscopy at Toyoshima Endoscopy Clinic between May, 2017 and October, 2020. From the clinic's endoscopy database, we extracted data on patient age, sex, endoscopist-assessed looping, colonoscopy duration, endoscopist experience, detection rate, and number of premalignant polyps. RESULTS: We assessed 12259 patients (mean age, 53.6 years; men, 50.7%). Looping occurred in 54.3% of the patients. Mild and severe looping were noted in 4399 and 2253 patients, respectively. The detection rates of adenomas, advanced adenomas, high-risk adenomas, clinically significant serrated polyps (CSSPs), and sessile serrated lesions (SSLs) were 44.7%, 2.0%, 9.9%, 8.9% and 3.5%, respectively. The mean numbers of adenomas and SSLs were 0.82 and 0.04, respectively. The detection rates of adenomas, high-risk adenomas, and CSSPs increased with looping severity (all P < 0.001). The number of adenomas increased with looping severity (P < 0.001). Multivariate analyses found that detection of adenomas, high-risk adenomas, and CSSPs was associated with severe looping (P < 0.001, P < 0.001, and P = 0.007, respectively) regardless of age, sex, time required for colonoscope insertion and withdrawal, and endoscopist experience. CONCLUSION: Looping severity was independently associated with high detection rates of premalignant polyps. Therefore, looping may predict the risk of metachronous colorectal cancer. Endoscopists should carefully examine the colorectum of patients with looping.

Increasing trend of Helicobacter pylori-uninfected gastric cancer without gastric atrophy.

The prevalence of Helicobacter pylori (H. pylori) has decreased during several decades due to improvements in the sanitary environment in Japan. Consequently, a relative increase in the incidence of H. pylori-uninfected gastric cancer is expected. We analyzed the trends in H. pylori-uninfected gastric cancer. Two hundred fifty-eight patients with gastric cancer were retrospectively analyzed. The study was divided into four periods: 2008-2011 (first period), 2012-2014 (second period), 2015-2017 (third period), and 2018-2021 (fourth period). The status of H. pylori infection was divided into four categories: uninfected, successful eradication, spontaneous eradication, and persistent infection. Gastric mucosal atrophy was divided into six grades according to the Kimura-Takemoto classification. The proportion of H. pylori infections significantly changed over the study period (p = 0.007). In particular, the rate of H. pylori-uninfected gastric cancer tended to increase over time (0%, 2.9%, 4.9%, and 13.4% in the first, second, third, and fourth periods, respectively; p = 0.0013). The rate of no atrophy (C-0) in gastric cancer tended to increase over time (0%, 2.9%, 4.9%, and 11.0% in the first, second, third, and fourth periods, respectively; p = 0.0046). In conclusion, the rate of H. pylori-uninfected gastric cancer without gastric atrophy tended to increase over time.

Texture and color enhancement imaging in magnifying endoscopic evaluation of colorectal adenomas.

BACKGROUND: Olympus Corporation has developed texture and color enhancement imaging (TXI) as a novel image-enhancing endoscopic technique. AIM: To investigate the effectiveness of TXI in identifying colorectal adenomas using magnifying observation. METHODS: Colorectal adenomas were observed by magnified endoscopy using white light imaging (WLI), TXI, narrow band imaging (NBI), and chromoendoscopy (CE). This study adopted mode 1 of TXI. Adenomas were confirmed by histological examination. TXI visibility was compared with the visibility of WLI, NBI, and CE for tumor margin, and vessel and surface patterns of the Japan NBI expert team (JNET) classification. Three expert endoscopists and three non-expert endoscopists evaluated the visibility scores, which were classified as 1, 2, 3, and 4. RESULTS: Sixty-one consecutive adenomas were evaluated. The visibility score for tumor margin of TXI (3.47 ± 0.79) was significantly higher than that of WLI (2.86 ± 1.02, P < 0.001), but lower than that of NBI (3.76 ± 0.52, P < 0.001), regardless of the endoscopist's expertise. TXI (3.05 ± 0.79) had a higher visibility score for the vessel pattern of JNET classification than WLI (2.17 ± 0.90, P < 0.001) and CE (2.47 ± 0.87, P < 0.001), but lower visibility score than NBI (3.79 ± 0.47, P < 0.001), regardless of the experience of endoscopists. For the visibility score for the surface pattern of JNET classification, TXI (2.89 ± 0.85) was superior to WLI (1.95 ± 0.79, P < 0.01) and CE (2.75 ± 0.90, P = 0.002), but inferior to NBI (3.67 ± 0.55, P < 0.001). CONCLUSION: TXI provided higher visibility than WLI, lower than NBI, and comparable to or higher than CE in the magnified observation of colorectal adenomas.

Consistency between the endoscopic Kyoto classification and pathological updated Sydney system for gastritis: A cross-sectional study.

BACKGROUND: Two methods are used to evaluate gastritis: the updated Sydney system (USS) with pathology and Kyoto classification, a new endoscopy-based diagnostic criterion for which evidence is accumulating. However, the consistency of their results is unclear. This study investigated the consistency of their results. METHODS: Patients who underwent esophagogastroduodenoscopy and were evaluated for Helicobacter pylori infection for the first time were eligible. The association between corpus and antral USS scores (neutrophil activity, chronic inflammation, atrophy, and intestinal metaplasia) and Kyoto classification scores (atrophy, intestinal metaplasia, enlarged folds, nodularity, and diffuse redness) was assessed. RESULTS: Seven-hundred-seventeen patients (mean age, 49.2 years; female sex, 57.9%; 450 H. pylori-positive and 267 H. pylori-negative patients) were enrolled. All endoscopic gastritis cases in the Kyoto classification were associated with high corpus and antral USS scores for neutrophil activity and chronic inflammation. A subanalysis was performed for H. pylori-positive patients. Regarding atrophy and intestinal metaplasia, endoscopic findings were associated with USS scores. Enlarged folds, nodularity, and diffuse redness were associated with high corpus USS scores for neutrophil activity and chronic inflammation, but with low antral USS scores for atrophy and intestinal metaplasia. The Kyoto classification scores were also associated with the pathological topographic distribution of neutrophil activity and intestinal metaplasia. CONCLUSIONS: Among H. pylori-positive individuals, endoscopic and pathological diagnoses were consistent with atrophy and intestinal metaplasia. Enlarged folds, nodularity, and diffuse redness were associated with pathological inflammation (neutrophil activity and chronic inflammation) of the corpus; however, they were inversely associated with pathological atrophy and intestinal metaplasia. The endoscopy-based Kyoto classification of gastritis partially reflects pathology.

Enlarged folds on endoscopic gastritis as a predictor for submucosal invasion of gastric cancers.

BACKGROUND: Accurate diagnosis of the depth of gastric cancer invasion is crucial in clinical practice. The diagnosis of gastric cancer depth is often made using endoscopic characteristics of the tumor and its margins; however, evaluating invasion depth based on endoscopic background gastritis remains unclear. AIM: To investigate predicting submucosal invasion using the endoscopy-based Kyoto classification of gastritis. METHODS: Patients with gastric cancer detected on esophagogastroduodenoscopy at Toyoshima Endoscopy Clinic were enrolled. We analyzed the effects of patient and tumor characteristics, including age, sex, body mass index, surveillance endoscopy within 2 years, current Helicobacter pylori infection, the Kyoto classification, and Lauren's tumor type, on submucosal tumor invasion and curative endoscopic resection. The Kyoto classification included atrophy, intestinal metaplasia, enlarged folds, nodularity, and diffuse redness. Atrophy was characterized by non-reddish and low mucosa. Intestinal metaplasia was detected as patchy whitish or grayish-white flat elevations, forming an irregular uneven surface. An enlarged fold referred to a fold width ≥ 5 mm in the greater curvature of the corpus. Nodularity was characterized by goosebump-like multiple nodules in the antrum. Diffuse redness was characterized by uniform reddish non-atrophic mucosa in the greater curvature of the corpus. RESULTS: A total of 266 gastric cancer patients (mean age, 66.7 years; male sex, 58.6%; mean body mass index, 22.8 kg/m2) were enrolled. Ninety-three patients underwent esophagogastroduodenoscopy for surveillance within 2 years, and 140 had current Helicobacter pylori infection. The mean Kyoto score was 4.54. Fifty-eight cancers were diffuse-type, and 87 cancers had invaded the submucosa. Multivariate analysis revealed that low body mass index (odds ratio 0.88, P = 0.02), no surveillance esophagogastroduodenoscopy within 2 years (odds ratio 0.15, P < 0.001), endoscopic enlarged folds of gastritis (odds ratio 3.39, P = 0.001), and Lauren's diffuse-type (odds ratio 5.09, P < 0.001) were independently associated with submucosal invasion. Similar results were obtained with curative endoscopic resection. Among cancer patients with enlarged folds, severely enlarged folds (width ≥ 10 mm) were more related to submucosal invasion than mildly enlarged folds (width 5-9 mm, P < 0.001). CONCLUSION: Enlarged folds of gastritis were associated with submucosal invasion. Endoscopic observation of background gastritis as well as the lesion itself may help diagnose the depth of cancer invasion.

Risk Factors for Prolonged Hospital Stay after Endoscopy.

BACKGROUND/AIMS: The recovery room used after endoscopy has limited capacity, and an efficient flow of the endoscopy unit is desired. We investigated the duration of hospital stay after endoscopy and the risk factors for prolonged hospital stay among outpatients. METHODS: We retrospectively studied consecutive patients who underwent esophagogastroduodenoscopy or colonoscopy at the Toyoshima Endoscopy Clinic. We collected data on age, sex, body weight, midazolam and pethidine dosage, respiratory depression during endoscopy, and duration of hospital stay after endoscopy (scope out to check out). Risk factors for prolonged hospital stay (>100 minutes) were identified using multiple logistic regression analysis. RESULTS: We enrolled 3,898 patients, including 3,517 (90.2%) patients tested under sedation and 381 (9.8%) patients tested without sedation. Overall, 442 (11.3%) patients had prolonged stay (>100 min). The mean time difference between sedation group and non-sedation group was 44.2 minutes for esophagogastroduodenoscopy and 39.1 minutes for colonoscopy. Age (odds ratio [OR], 1.025; 95% confidence interval [CI], 1.014-1.036), female sex (OR, 1.657; 95% CI, 1.220-2.249), and midazolam dose (OR, 1.019; 95% CI, 1.013-1.026) were independently associated with prolonged hospital stay after esophagogastroduodenoscopy, with similar results for colonoscopy. CONCLUSION: Old age, female sex, and midazolam dose were independent risk factors for prolonged hospital stay after endoscopy.

A single nucleotide polymorphism in Prostate Stem Cell Antigen is associated with endoscopic grading in Kyoto classification of gastritis.

The risk allele of a single nucleotide polymorphism (SNP) rs2294008 in the Prostate stem cell antigen (PSCA) gene is strongly associated with gastric cancer. Although the Kyoto classification score is believed to be an indicator of gastric cancer risk, it lacks supporting genetic evidence. We investigated the effect of this risk allele of PSCA SNP on the Kyoto score. Participants without a history of gastric cancer or Helicobacter pylori (H. pylori) eradication underwent esophagogastroduodenoscopy, H. pylori evaluation, and SNP genotyping. The Kyoto score is the sum of scores obtained from endoscopy-based atrophy, intestinal metaplasia, enlarged folds, nodularity, and diffuse redness. The Kyoto score is novel in the light of scoring for gastritis. A total of 323 patients were enrolled (number of individuals with genotype CC: 52; CT: 140; TT: 131, average age: 50.1 years, male: 50.8%). The patient baseline characteristics including age, sex, body mass index, smoking, drinking, family history of gastric cancer, and H. pylori status had no association with PSCA SNP. The Kyoto score was higher in T (CT or TT genotype; risk allele) carriers than in CC carriers. Atrophy, enlarged folds, and diffuse redness scores were higher in T allele carriers (risk allele) than in CC genotype individuals. In multivariate analysis, the Kyoto score was independently associated with PSCA SNP (OR: 1.30, p = 0.012). Thus, the Kyoto score was associated with a genetic predisposition.

Kyoto classification in patients who developed multiple gastric carcinomas after Helicobacter pylori eradication.

BACKGROUND: Endoscopic Kyoto classification predicts gastric cancer risk; however, the score in the patients with primary gastric cancer after Helicobacter pylori (H. pylori) eradication therapy is unknown. AIM: To elucidate the Kyoto classification score in patients with both single gastric cancer and multiple gastric cancers developed after H. pylori eradication. METHODS: The endoscopist recorded the Kyoto classification at the endoscope and the Kyoto classification score at the time of the first diagnosis of gastric cancer after H. pylori eradication. The score was compared between single gastric cancer group and multiple gastric cancers group. RESULTS: The Kyoto score at the time of diagnosis of 45 cases of gastric cancer after H. pylori eradication was 4.0 points in average. The score was 3.8 points in the single gastric cancer group, and 5.1 points in the multiple gastric cancers group. The multiple group had a significantly higher score than the single group (P = 0.016). In the multiple gastric cancers group, all the patients (7/7) had 5 or higher Kyoto score, while in single gastric cancer group, the proportion of patients with a score of 5 or higher was less than half, or 44.7% (17/38). CONCLUSION: Patients diagnosed with gastric cancer after H. pylori eradication tended to have advanced gastritis. In particular, in cases of multiple gastric cancers developed after H. pylori eradication, the endoscopic Kyoto classification score tended to be 5 or higher in patients with an open type atrophic gastritis and the intestinal metaplasia extended to the corpus.

Human iPSC-Derived Posterior Gut Progenitors Are Expandable and Capable of Forming Gut and Liver Organoids.

Early endoderm progenitors naturally possess robust propagating potential to develop a majority of meter-long gastrointestinal tracts and are therefore considered as a promising source for therapy. Here, we demonstrated the reproducible generation of human CDX2+ posterior gut endoderm cells (PGECs) from five induced pluripotent stem cell clones by manipulating FGF, TGF, and WNT signaling. Transcriptome analysis suggested that putative PGECs harbored an intermediate signature profile between definitive endoderm and organ-specific endoderm. We found that combinatorial EGF, VEGF, FGF2, Chir99021, and A83-01 treatments selectively amplify storable PGECs up to 1021 cell scale without any gene transduction or feeder use. PGECs, compared with induced pluripotent stem cells, showed stable differentiation propensity into multiple endodermal lineages without teratoma formation. Furthermore, transplantation of PGEC-derived liver bud organoids showed therapeutic potential against fulminant liver failure. Together, the robustly amplified PGECs may be a promising cellular source for endoderm-derived organoids in studying human development, modeling disease, and, ultimately, therapy.

Regulation of antigen-receptor gene assembly in hagfish.

Variable lymphocyte receptors (VLRs) are antigen receptors in the jawless vertebrates lamprey and hagfish. VLR genes are classified into VLRA and VLRB, and lymphocytes expressing VLRA are T-cell-like, whereas those expressing VLRB are B-cell-like in the sea lamprey. Diverse VLR genes are assembled somatically in lymphocytes; however, how the assembly is regulated is still largely unknown. Here, we analyse VLR gene assembly at the single-cell level in the inshore hagfish (Eptatretus burgeri). Each lymphocyte assembles and transcribes only one type of VLR gene, either VLRA or VLRB. In general, monoallelic assembly of VLR was observed, but diallelic assembly was found in some cases--in many of which, one allele was functional and the other was defective. In fact, all VLR-assembled lymphocytes contained at least one functional VLR gene. Together, these results indicate a feedback inhibition of VLR assembly and selection of VLR-positive lymphocytes.