BACKGROUNDEMR is an accepted treatment for early esophageal carcinoma. However, resection of a large mucosal area often causes postoperative esophageal stricture.OBJECTIVETo investigate the efficacy of autologous adipose tissue-derived stromal cells (ADSCs) for prevention of stricture formation after EMR in dogs.DESIGNAnimal study.SETTINGUniversity research center.INTERVENTIONTen beagle dogs were randomized into a control group and an ADSCs-injected (ADSC) group. The ADSCs were isolated from autologous adipose tissue. Immediately after circumferential esophageal EMR, about 5 × 10(6) ADSCs suspended in 8 mL of phosphate-buffered saline solution were injected endoscopically into the residual submucosa of the ADSC group, whereas the control group received only 8 mL of phosphate-buffered saline solution.MAIN OUTCOME MEASUREMENTSDysphagia score, weight loss, rate of mucosal constriction, and histologic assessments.RESULTSIn the control and ADSC groups, the median dysphagia scores were 4 and 1 (P < .043), the mean degrees of mucosal constriction were 75.7% and 45.3% (P < .008), and the numbers of nascent microvessels in the submucosal layer were 7.4 and 16.2 per unit area (P = .007), respectively. Atrophy and fibrosis of the muscularis propria layer were observed in the control group.LIMITATIONSAnimal study, small sample size.CONCLUSIONInjection therapy with autologous ADSCs suppresses constriction of the esophageal mucosa and improves clinical symptoms after circumferential EMR in this canine model.