Scandinavian Journal of Gastroenterology. 2014; 49: 30–34
ORIGINAL ARTICLE
Scand J Gastroenterol Downloaded from informahealthcare.com by McMaster University on 12/28/14 For personal use only.
Esophageal stricture induced by an ultraslim upper endoscope in a novel rabbit model of corrosive injury
JAE CHUL HWANG1*, BOHWAN JIN2*, JANG-HEE KIM3, SUN GYO LIM1, MIN JAE YANG1, SOON SUN KIM1, SUNG JAE SHIN1, KEE MYUNG LEE1 & JIN HONG KIM1 1
Department of Gastroenterology, Ajou University School of Medicine, Suwon, Korea, 2Natural Products Research Institute, Gyeonggi Institute of Science & Technology Promotion, Suwon, Korea, and 3Department of Pathology, Ajou University School of Medicine, Suwon, Korea
Abstract Objective. Benign esophageal strictures are regularly encountered problems in clinical practice. The management of refractory benign esophageal stricture, which fails to establish adequate food passage despite multiple dilatation sessions, has been considered challenging. Experimental animal models are essential for the development of effective treatment methods. The aim of this study was to establish a new animal model of benign esophageal stricture using rabbits. Material and methods. Corrosive injury of the esophagus was induced by administration of 1 ml of 1.5% sodium hydroxide in eight rabbits using an ultraslim upper endoscope equipped with a 5-Fr polytetrafluoroethylene tube and 5-Fr balloon catheter. Two weeks after corrosive injury, endoscopic examination was performed to confirm the state of the injury site. Four weeks after corrosive injury, the esophageal stricture was assessed by endoscopy and esophagography. All animals were then euthanized. Results. Two weeks after corrosive injury, endoscopic examination showed that ulceration had been induced. Four weeks after corrosive injury, endoscopic, radiologic and gross examinations showed that esophageal stricture had been induced without complications in all animals. The esophageal lumen diameter was reduced by an average of 51.8% (range, 48.3%–57.2%), and the mean stricture length was 25.7 mm (range, 20.1–29.3 mm). Microscopic examination revealed focal ulceration and submucosal thickening secondary to fibrosis. Conclusions. Rabbit esophageal stricture induced by endoscopic delivery of a small amount of low-concentration sodium hydroxide is a relatively simple, safe, and reproducible animal model. This model may be useful in the development of new treatment methods for esophageal stricture.
Key Words: animal, endoscopy, esophageal stenosis, models
Introduction Benign esophageal strictures are commonly encountered problems in clinical practice. These strictures can be caused by deep-tissue esophageal injury of various causes such as caustic ingestion, radiation injury, anastomotic strictures, and peptic ulceration [1–3]. Most of these strictures can be effectively treated with endoscopic bougie or balloon dilation [4]. However, there is a small subgroup of patients (10%) who fail to establish adequate food passage despite multiple dilatation
sessions [5,6]. These patients are considered to have a refractory benign esophageal stricture, the management of which has been considered challenging [6,7]. Multiple procedures are available for the treatment of refractory benign esophageal stricture, but none of them are completely satisfactory. Experimental animal models are essential to develop effective treatment techniques, and evidence of successful new techniques is mandatory before clinical application. The aim of this study was to establish a new animal model of benign esophageal stricture using rabbits.
Correspondence: Jin Hong Kim, MD PhD, Department of Gastroenterology, Ajou University School of Medicine, San-5, Woncheon-dong, Yongtong-gu, Suwon 442-749, Republic of Korea. Tel: +82 31 219 6937. Fax: +82 31 219 5999. E-mail: [email protected] *These authors contributed equally to this work and share first authorship.
(Received 17 August 2013; revised 17 September 2013; accepted 18 September 2013) ISSN 0036-5521 print/ISSN 1502-7708 online 2014 Informa Healthcare DOI: 10.3109/00365521.2013.848229
Esophageal stricture in a rabbit model Methods
Scand J Gastroenterol Downloaded from informahealthcare.com by McMaster University on 12/28/14 For personal use only.
Animals and anesthesia Eight New Zealand white rabbits (male, 10 weeks of age, 3.8–4.8 kg) were obtained from the laboratory animal research center at Cheonan Yonam College (Korea). The study was approved by the Institutional Animal Care and Use Committee (IACUC) at Ajou University School of Medicine (approval no. amc40). The animals were maintained in the laboratory animal center of Ajou University School of Medicine. Animals were housed in stainless steel cages and provided with standard rabbit pellet diet and water ad libitum. They were intramuscularly anesthetized with ketamine (35 mg/kg) and xylazine (5 mg/kg) [8]. Endoscopic procedure After a 24-h fast, the rabbits were positioned in the left lateral decubitus position. Corrosive injury of the esophagus was induced using an ultraslim upper endoscope (GIF-XP260N; Olympus Optical Co. Ltd., Tokyo, Japan) with a 2-mm working channel and a 5-mm tip diameter. A 5-Fr balloon catheter with a channel and maximal 12-mm diameter balloon (MTW Endoskopie, Wesel, Germany) and a 5-Fr polytetrafluoroethylene (PTFE) tube (Daikin Industries, Ltd., Osaka, Japan) were used as accessories for inducing corrosive injury of the esophagus. The ultraslim upper endoscope equipped with a 5-Fr PTFE tube was inserted to the mid-esophagus. After advancing the balloon catheter into the esophagus, the balloon was inflated to prevent caustic agent leakage, and 1 ml of 1.5% sodium hydroxide (NaOH) was administered into the esophagus through the PTFE tube. The balloon was maintained in position for 30 s; it was then deflated and removed. Antibiotics were not administered because severe enterocolitis often occurs in rabbits that are administered antibiotics [9]. All animals were allowed to resume regular feeding the day after the procedure. After 2 weeks of corrosive injury, endoscopic observation was performed to confirm the state of the injury site. After 4 weeks of corrosive injury, the esophageal stricture was assessed by endoscopy and esophagography. The degree of the stricture was measured during esophagography and corrected for magnification using the external diameter of the endoscope’s distal end as a reference. Histological examination All animals were euthanized 4 weeks after the procedure, and the esophagus was extirpated for gross observation and histological examination. After the
31
samples had been fixed in 10% formaldehyde for 48 h, each lesion was transversely sectioned at 4-mm intervals and embedded in paraffin. Prepared sections were stained with hematoxylin and eosin. Masson’s trichrome stain was also applied to evaluate collagen expression. Results All rabbits survived for the designated 4-week followup period and were weighed before being euthanized. The body weight decreased by 1000-fold increase risk of developing esophageal carcinoma [18], and the interval between corrosive ingestion and the development of carcinoma has ranged between 10 and 30 years [19]. In this study, all animals were euthanized 4 weeks after the procedure, and there was no finding of dysplasia in microscopic examination. In this study, we used rabbits, which afford the following several advantages. (1) The rabbit esophagus comprises three skeletal muscle layers, namely an inner longitudinal layer, outer longitudinal layer, and middle circular layer [10]. This anatomical arrangement allows for resistance to corrosive perforation and sufficient survival for esophageal stricture development. (2) The rabbit is large enough to undergo multiple endoscopic examinations with an ultraslim upper endoscope. (3) The rabbit is easier to
handle and less expensive to maintain than larger animals such as pigs. In conclusion, we have established a new rabbit model of esophageal stricture with endoscopic delivery of a small amount of a low-concentration corrosive agent. This model is technically simple, safe, and reproducible. It can be used to develop new, promising methods of esophageal stricture management.
Acknowledgment This work was supported by a 2008 grant from the Department of Medical Sciences, Graduate School of Ajou University. Declaration of interest: The authors have no commercial associations that might be a conflict of interest in relation to this article.
34
J. C. Hwang et al.
Scand J Gastroenterol Downloaded from informahealthcare.com by McMaster University on 12/28/14 For personal use only.
References [1] Ferguson DD. Evaluation and management of benign esophageal strictures. Dis Esophagus 2005;18:359–64. [2] Siersema PD, de Wijkerslooth LR. Dilation of refractory benign esophageal strictures. Gastrointest Endosc 2009;70: 1000–12. [3] Spechler SJ. AGA technical review on treatment of patients with dysphagia caused by benign disorders of the distal esophagus. Gastroenterology 1999;117:233–54. [4] Lew RJ, Kochman ML. A review of endoscopic methods of esophageal dilation. J Clin Gastroenterol 2002;35:117–26. [5] Boyce HW. Dilation of difficult benign esophageal strictures. Am J Gastroenterol 2005;100:744–5. [6] Kochman ML, McClave SA, Boyce HW. The refractory and the recurrent esophageal stricture: a definition. Gastrointest Endosc 2005;62:474–5. [7] de Wijkerslooth LR, Vleggaar FP, Siersema PD. Endoscopic management of difficult or recurrent esophageal strictures. Am J Gastroenterol 2011;106:2080–91; quiz 2092. [8] White GL, Holmes DD. A comparison of ketamine and the combination ketamine-xylazine for effective surgical anesthesia in the rabbit. Lab Anim Sci 1976;26:804–6. [9] Morris TH. Antibiotic therapeutics in laboratory animals. Lab Anim 1995;29:16–36. [10] Thompson JN. Corrosive esophageal injuries. II. An investigation of treatment methods and histochemical analysis of esophageal strictures in a new animal model. Laryngoscope 1987;97:1191–202.
[11] Perry Y, Epperly MW, Fernando HC, Klein E, Finkelstein S, Greenberger JS, et al. Photodynamic therapy induced esophageal stricture–an animal model: from mouse to pig. J Surg Res 2005;123:67–74. [12] Turkyilmaz Z, Sonmez K, Karabulut R, Gulbahar O, Poyraz A, Sancak B, et al. Mitomycin C decreases the rate of stricture formation in caustic esophageal burns in rats. Surgery 2009;145:219–25. [13] Honda M, Hori Y, Nakada A, Uji M, Nishizawa Y, Yamamoto K, et al. Use of adipose tissue-derived stromal cells for prevention of esophageal stricture after circumferential EMR in a canine model. Gastrointest Endosc 2011;73: 777–84. [14] Gehanno P, Guedon C. Inhibition of experimental esophageal lye strictures by penicillamine. Arch Otolaryngol 1981; 107:145–7. [15] Sakurai T, Miyazaki S, Miyata G, Satomi S, Hori Y. Autologous buccal keratinocyte implantation for the prevention of stenosis after EMR of the esophagus. Gastrointest Endosc 2007;66:167–73. [16] Kannan RY, Salacinski HJ, Butler PE, Hamilton G, Seifalian AM. Current status of prosthetic bypass grafts: a review. J Biomed Mater Res B Appl Biomater 2005;74: 570–81. [17] Hopkins RA, Postlethwait RW. Caustic burns and carcinoma of the esophagus. Ann Surg 1981;194:146–8. [18] Bigelow NH. Carcinoma of the esophagus developing at the site of lye stricture. Cancer 1953;6:1159–64. [19] Kay M, Wyllie R. Caustic ingestions in children. Curr Opin Pediatr 2009;21:651–4.
ORIGINAL ARTICLE
Scand J Gastroenterol Downloaded from informahealthcare.com by McMaster University on 12/28/14 For personal use only.
Esophageal stricture induced by an ultraslim upper endoscope in a novel rabbit model of corrosive injury
JAE CHUL HWANG1*, BOHWAN JIN2*, JANG-HEE KIM3, SUN GYO LIM1, MIN JAE YANG1, SOON SUN KIM1, SUNG JAE SHIN1, KEE MYUNG LEE1 & JIN HONG KIM1 1
Department of Gastroenterology, Ajou University School of Medicine, Suwon, Korea, 2Natural Products Research Institute, Gyeonggi Institute of Science & Technology Promotion, Suwon, Korea, and 3Department of Pathology, Ajou University School of Medicine, Suwon, Korea
Abstract Objective. Benign esophageal strictures are regularly encountered problems in clinical practice. The management of refractory benign esophageal stricture, which fails to establish adequate food passage despite multiple dilatation sessions, has been considered challenging. Experimental animal models are essential for the development of effective treatment methods. The aim of this study was to establish a new animal model of benign esophageal stricture using rabbits. Material and methods. Corrosive injury of the esophagus was induced by administration of 1 ml of 1.5% sodium hydroxide in eight rabbits using an ultraslim upper endoscope equipped with a 5-Fr polytetrafluoroethylene tube and 5-Fr balloon catheter. Two weeks after corrosive injury, endoscopic examination was performed to confirm the state of the injury site. Four weeks after corrosive injury, the esophageal stricture was assessed by endoscopy and esophagography. All animals were then euthanized. Results. Two weeks after corrosive injury, endoscopic examination showed that ulceration had been induced. Four weeks after corrosive injury, endoscopic, radiologic and gross examinations showed that esophageal stricture had been induced without complications in all animals. The esophageal lumen diameter was reduced by an average of 51.8% (range, 48.3%–57.2%), and the mean stricture length was 25.7 mm (range, 20.1–29.3 mm). Microscopic examination revealed focal ulceration and submucosal thickening secondary to fibrosis. Conclusions. Rabbit esophageal stricture induced by endoscopic delivery of a small amount of low-concentration sodium hydroxide is a relatively simple, safe, and reproducible animal model. This model may be useful in the development of new treatment methods for esophageal stricture.
Key Words: animal, endoscopy, esophageal stenosis, models
Introduction Benign esophageal strictures are commonly encountered problems in clinical practice. These strictures can be caused by deep-tissue esophageal injury of various causes such as caustic ingestion, radiation injury, anastomotic strictures, and peptic ulceration [1–3]. Most of these strictures can be effectively treated with endoscopic bougie or balloon dilation [4]. However, there is a small subgroup of patients (10%) who fail to establish adequate food passage despite multiple dilatation
sessions [5,6]. These patients are considered to have a refractory benign esophageal stricture, the management of which has been considered challenging [6,7]. Multiple procedures are available for the treatment of refractory benign esophageal stricture, but none of them are completely satisfactory. Experimental animal models are essential to develop effective treatment techniques, and evidence of successful new techniques is mandatory before clinical application. The aim of this study was to establish a new animal model of benign esophageal stricture using rabbits.
Correspondence: Jin Hong Kim, MD PhD, Department of Gastroenterology, Ajou University School of Medicine, San-5, Woncheon-dong, Yongtong-gu, Suwon 442-749, Republic of Korea. Tel: +82 31 219 6937. Fax: +82 31 219 5999. E-mail: [email protected] *These authors contributed equally to this work and share first authorship.
(Received 17 August 2013; revised 17 September 2013; accepted 18 September 2013) ISSN 0036-5521 print/ISSN 1502-7708 online 2014 Informa Healthcare DOI: 10.3109/00365521.2013.848229
Esophageal stricture in a rabbit model Methods
Scand J Gastroenterol Downloaded from informahealthcare.com by McMaster University on 12/28/14 For personal use only.
Animals and anesthesia Eight New Zealand white rabbits (male, 10 weeks of age, 3.8–4.8 kg) were obtained from the laboratory animal research center at Cheonan Yonam College (Korea). The study was approved by the Institutional Animal Care and Use Committee (IACUC) at Ajou University School of Medicine (approval no. amc40). The animals were maintained in the laboratory animal center of Ajou University School of Medicine. Animals were housed in stainless steel cages and provided with standard rabbit pellet diet and water ad libitum. They were intramuscularly anesthetized with ketamine (35 mg/kg) and xylazine (5 mg/kg) [8]. Endoscopic procedure After a 24-h fast, the rabbits were positioned in the left lateral decubitus position. Corrosive injury of the esophagus was induced using an ultraslim upper endoscope (GIF-XP260N; Olympus Optical Co. Ltd., Tokyo, Japan) with a 2-mm working channel and a 5-mm tip diameter. A 5-Fr balloon catheter with a channel and maximal 12-mm diameter balloon (MTW Endoskopie, Wesel, Germany) and a 5-Fr polytetrafluoroethylene (PTFE) tube (Daikin Industries, Ltd., Osaka, Japan) were used as accessories for inducing corrosive injury of the esophagus. The ultraslim upper endoscope equipped with a 5-Fr PTFE tube was inserted to the mid-esophagus. After advancing the balloon catheter into the esophagus, the balloon was inflated to prevent caustic agent leakage, and 1 ml of 1.5% sodium hydroxide (NaOH) was administered into the esophagus through the PTFE tube. The balloon was maintained in position for 30 s; it was then deflated and removed. Antibiotics were not administered because severe enterocolitis often occurs in rabbits that are administered antibiotics [9]. All animals were allowed to resume regular feeding the day after the procedure. After 2 weeks of corrosive injury, endoscopic observation was performed to confirm the state of the injury site. After 4 weeks of corrosive injury, the esophageal stricture was assessed by endoscopy and esophagography. The degree of the stricture was measured during esophagography and corrected for magnification using the external diameter of the endoscope’s distal end as a reference. Histological examination All animals were euthanized 4 weeks after the procedure, and the esophagus was extirpated for gross observation and histological examination. After the
31
samples had been fixed in 10% formaldehyde for 48 h, each lesion was transversely sectioned at 4-mm intervals and embedded in paraffin. Prepared sections were stained with hematoxylin and eosin. Masson’s trichrome stain was also applied to evaluate collagen expression. Results All rabbits survived for the designated 4-week followup period and were weighed before being euthanized. The body weight decreased by 1000-fold increase risk of developing esophageal carcinoma [18], and the interval between corrosive ingestion and the development of carcinoma has ranged between 10 and 30 years [19]. In this study, all animals were euthanized 4 weeks after the procedure, and there was no finding of dysplasia in microscopic examination. In this study, we used rabbits, which afford the following several advantages. (1) The rabbit esophagus comprises three skeletal muscle layers, namely an inner longitudinal layer, outer longitudinal layer, and middle circular layer [10]. This anatomical arrangement allows for resistance to corrosive perforation and sufficient survival for esophageal stricture development. (2) The rabbit is large enough to undergo multiple endoscopic examinations with an ultraslim upper endoscope. (3) The rabbit is easier to
handle and less expensive to maintain than larger animals such as pigs. In conclusion, we have established a new rabbit model of esophageal stricture with endoscopic delivery of a small amount of a low-concentration corrosive agent. This model is technically simple, safe, and reproducible. It can be used to develop new, promising methods of esophageal stricture management.
Acknowledgment This work was supported by a 2008 grant from the Department of Medical Sciences, Graduate School of Ajou University. Declaration of interest: The authors have no commercial associations that might be a conflict of interest in relation to this article.
34
J. C. Hwang et al.
Scand J Gastroenterol Downloaded from informahealthcare.com by McMaster University on 12/28/14 For personal use only.
References [1] Ferguson DD. Evaluation and management of benign esophageal strictures. Dis Esophagus 2005;18:359–64. [2] Siersema PD, de Wijkerslooth LR. Dilation of refractory benign esophageal strictures. Gastrointest Endosc 2009;70: 1000–12. [3] Spechler SJ. AGA technical review on treatment of patients with dysphagia caused by benign disorders of the distal esophagus. Gastroenterology 1999;117:233–54. [4] Lew RJ, Kochman ML. A review of endoscopic methods of esophageal dilation. J Clin Gastroenterol 2002;35:117–26. [5] Boyce HW. Dilation of difficult benign esophageal strictures. Am J Gastroenterol 2005;100:744–5. [6] Kochman ML, McClave SA, Boyce HW. The refractory and the recurrent esophageal stricture: a definition. Gastrointest Endosc 2005;62:474–5. [7] de Wijkerslooth LR, Vleggaar FP, Siersema PD. Endoscopic management of difficult or recurrent esophageal strictures. Am J Gastroenterol 2011;106:2080–91; quiz 2092. [8] White GL, Holmes DD. A comparison of ketamine and the combination ketamine-xylazine for effective surgical anesthesia in the rabbit. Lab Anim Sci 1976;26:804–6. [9] Morris TH. Antibiotic therapeutics in laboratory animals. Lab Anim 1995;29:16–36. [10] Thompson JN. Corrosive esophageal injuries. II. An investigation of treatment methods and histochemical analysis of esophageal strictures in a new animal model. Laryngoscope 1987;97:1191–202.
[11] Perry Y, Epperly MW, Fernando HC, Klein E, Finkelstein S, Greenberger JS, et al. Photodynamic therapy induced esophageal stricture–an animal model: from mouse to pig. J Surg Res 2005;123:67–74. [12] Turkyilmaz Z, Sonmez K, Karabulut R, Gulbahar O, Poyraz A, Sancak B, et al. Mitomycin C decreases the rate of stricture formation in caustic esophageal burns in rats. Surgery 2009;145:219–25. [13] Honda M, Hori Y, Nakada A, Uji M, Nishizawa Y, Yamamoto K, et al. Use of adipose tissue-derived stromal cells for prevention of esophageal stricture after circumferential EMR in a canine model. Gastrointest Endosc 2011;73: 777–84. [14] Gehanno P, Guedon C. Inhibition of experimental esophageal lye strictures by penicillamine. Arch Otolaryngol 1981; 107:145–7. [15] Sakurai T, Miyazaki S, Miyata G, Satomi S, Hori Y. Autologous buccal keratinocyte implantation for the prevention of stenosis after EMR of the esophagus. Gastrointest Endosc 2007;66:167–73. [16] Kannan RY, Salacinski HJ, Butler PE, Hamilton G, Seifalian AM. Current status of prosthetic bypass grafts: a review. J Biomed Mater Res B Appl Biomater 2005;74: 570–81. [17] Hopkins RA, Postlethwait RW. Caustic burns and carcinoma of the esophagus. Ann Surg 1981;194:146–8. [18] Bigelow NH. Carcinoma of the esophagus developing at the site of lye stricture. Cancer 1953;6:1159–64. [19] Kay M, Wyllie R. Caustic ingestions in children. Curr Opin Pediatr 2009;21:651–4.
