Systemic treatment with recombinant human epidermal growth factor accelerates healing of sclerotherapy-induced esophageal ulcers and prevents esophageal stricture formations in pigs

A new protective gel to facilitate ulcer healing in artificial ulcers following oesophageal endoscopic submucosal dissection: a multicentre, randomized trial

There are significant risks of adverse events following oesophageal endoscopic submucosal dissection (ESD), such as stricture, delayed bleeding and perforation. Therefore, it is necessary to protect artificial ulcers and promote the healing process. The current study was performed to investigate the protective role of a novel gel against oesophageal ESD-associated wounds. This was a multicentre, randomized, single-blind, controlled trial that recruited participants who underwent oesophageal ESD in four hospitals in China. Participants were randomly assigned to the control or experimental group in a 1:1 ratio and the gel was used after ESD in the latter. Masking of the study group allocations was only attempted for participants. The participants were instructed to report any adverse events on post-ESD days 1, 14, and 30. Moreover, repeat endoscopy was performed at the 2-week follow-up to confirm wound healing. Among the 92 recruited patients, 81 completed the study. In the experimental group, the healing rates were significantly higher than those in the control group (83.89 ± 9.51% vs. 73.28 ± 17.81%, P = 0.0013). Participants reported no severe adverse events during the follow-up period. In conclusion, this novel gel could safely, effectively, and conveniently accelerate wound healing following oesophageal ESD. Therefore, we recommend applying this gel in daily clinical practice.

Experimental model of portal hypertension and esophagogastric varices in minipigs: pressure and endoscopic pilot study

INTRODUCTION

Portal hypertension still represents an important health problem worldwide. In the search for knowledge regarding this syndrome, experimental studies with animal models have proven to be useful to point the direction to be taken in future randomized clinical trials.

PURPOSE

To validate the experimental model of portal hypertension and esophagogastric varices in a medium-sized animal.

METHODS

This study included five minipigs br1. Midline laparotomy with dissection of the portal vein and production of a calibrated stenosis of this vein was performed. Measurement of pressure in the portal venous and digestive endoscopic were performed before and five weeks after the production of a stenosis.

RESULTS

All animals were 8 months old, average weight of 17 ± 2.5 kg. The mean pressure of the portal vein immediately before the partial ligation of the portal vein was 8.9 + 1.6 mm Hg, with 26.6 + 5.4 mm Hg in the second measurement five weeks later (p < 0.05). No gastroesophageal varices or hypertensive portal gastropathy were seen at endoscopy procedures in our sample at any time in the study.

CONCLUSION

Portal vein ligation in minipigs has been validated in the production of portal hypertension, but not in the formation of esophageal varices.

Multifunctional Hydrophobized Microparticles for Accelerated Wound Healing after Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) provides strong therapeutic benefits for early gastrointestinal cancer as a minimally invasive treatment. However, there is currently no reliable treatment to prevent scar contracture resulting from ESD which may lead to cicatricial stricture. Herein, a multifunctional colloidal wound dressing to promote tissue regeneration after ESD is demonstrated. This sprayable wound dressing, composed of hydrophobized microparticles, exhibits the multifunctionality necessary for wound healing including tissue adhesiveness, blood coagulation, re-epithelialization, angiogenesis, and controlled inflammation based on hydrophobic interaction with biological systems. An in vivo feasibility study using swine gastric ESD models reveals that this colloidal wound dressing suppresses fibrosis and accelerates wound healing. Multifunctional colloidal and sprayable wound dressings have an enormous therapeutic potential for use in a wide range of biomedical applications including accelerated wound healing after ESD, prevention of perforation, and the treatment of inflammatory diseases.

Self-assembling peptide matrix for the prevention of esophageal stricture after endoscopic resection: a randomized controlled trial in a porcine model

Esophageal stricture formation after extensive endoscopic resection remains a major limitation of endoscopic therapy for early esophageal neoplasia. This study assessed a recently developed self-assembling peptide (SAP) matrix as a wound dressing after endoscopic resection for the prevention of esophageal stricture. Ten pigs were randomly assigned to the SAP or the control group after undergoing a 5-cm-long circumferential endoscopic submucosal dissection of the lower esophagus. Esophageal diameter on endoscopy and esophagogram, weight variation, and histological measurements of fibrosis, granulation tissue, and neoepithelium were assessed in each animal. The rate of esophageal stricture at day 14 was 40% in the SAP-treated group versus 100% in the control group (P = 0.2). Median interquartile range (IQR) esophageal diameter at day 14 was 8 mm (2.5-9) in the SAP-treated group versus 4 mm (3-4) in the control group (P = 0.13). The median (IQR) stricture indexes on esophagograms at day 14 were 0.32 (0.14-0.48) and 0.26 (0.14-0.33) in the SAP-treated and control groups, respectively (P = 0.42). Median (IQR) weight variation during the study was +0.2 (-7.4; +1.8) and -3.8 (-5.4; +0.6) in the SAP-treated and control groups, respectively (P = 0.9). Fibrosis, granulation tissue, and neoepithelium were not significantly different between the groups. The application of SAP matrix on esophageal wounds after a circumferential endoscopic submucosal dissection delayed the onset of esophageal stricture in a porcine model.

Exposure assessment of epidermal growth factor to various tissues in mice after intravenous and subcutaneous administration

OBJECTIVES

This study was conducted to examine the tissue distribution of human recombinant epidermal growth factor (EGF) after multiple intravenous and subcutaneous injections in mice.

METHODS

Male BALB/c mice were divided into (1) EGF 1 mg/kg intravenous dose, (2) EGF 5 mg/kg intravenous dose, (3) drug-free intravenous control, (4) EGF 1 mg/kg subcutaneous dose, (5) EGF 5 mg/kg subcutaneous dose and (6) drug-free subcutaneous control groups. EGF and drug-free dosing solutions were injected by intravenous and subcutaneous injections once a day for 3 days. EGF concentrations in serum and tissues of kidney, liver, lung, small intestine and tongue were determined by ELISA.

KEY FINDINGS

As the intravenous and subcutaneous doses were increased from 1 to 5 mg/kg, serum Cmax and area under the concentration-time curve (AUC) values were increased dose-proportionally. In lung, tongue and small intestine, increases in AUC were dose-proportional after intravenous injections, but greater than dose-proportional after subcutaneous injections. The fold-increases in Cmax and AUC values were lowest in liver and highest in kidney.

CONCLUSION

Based on Cmax and AUC data, the systemic exposure achieved by subcutaneous injections was comparable with that achieved by intravenous injections.

Systematic review: the prevention of oesophageal stricture after endoscopic resection

BACKGROUND

Extensive endoscopic resections for the treatment of early oesophageal neoplasia can result in fibro-inflammatory strictures that require repeated interventions, which significantly alter the patients' quality of life.

AIMS

To review current evidence about the prevention of oesophageal strictures following endoscopic resections.

METHODS

Systematic search of PubMed and Embase from inception to March 2015 using appropriate keywords. All original publications in English were included, and articles on the treatment of oesophageal stricture were excluded.

RESULTS

Of the 461 hits, 62 studies were included in the analysis. Among the wound-protective strategies, polyglycolic acid sheets showed the most convincing evidence with a 37.5% stricture rate and excellent safety. Regenerative medicine, using cell sheets of autologous keratinocytes, resulted in a 25% stricture rate, although with cost and availability concerns. Among anti-proliferative treatment modalities, steroid treatment, either endoscopically injected triamcinolone in the resection wound or orally administered prednisolone, proved effective with an overall stricture rate of 13.5%, with safety concerns regarding late oesophageal perforations and infectious morbidity. Among mechanical treatment options, poorly effective and high-risk preventive balloon dilation tend to be replaced by prophylactic covered stent, with 18-28% stricture rates.

CONCLUSIONS

Although oral or locally injected steroids are promising options, no currently available technique is sufficiently efficient and devoid of significant safety concerns to recommend its routine use for the prevention of strictures after extensive endoscopic resection. Improving our knowledge in the mechanisms of oesophageal wound healing will guide the development of novel methods for stricture prevention.

Subcutaneous administration of epidermal growth factor: a true treatment option in case of postoperative liver failure?

Adequate hepatocyte regeneration is mandatory for successful recovery after liver resection. The role of epidermal growth factor (EGF), by subcutaneous injection as a simple route, has not been clearly elucidated yet. Wistar rats underwent 70 or 90% hepatectomy, respectively, and were treated with EGF at day 2 and 3 or served as non-EGF-treated controls. Postoperatively, proliferative parameters (weight of liver remnants, number of mitotic and Ki-67 positive cells, expression of cyclin D1 protein) were evaluated. After 90% hepatectomy, 5 day survival was recorded following EGF treatment using different dosages. A significant increase of hepatocellular proliferation was observed after 70% hepatectomy. However, survival following 90% hepatectomy was not as positively affected, irrespective of EGF dosage, with most animals dead before EGF application was completed. Subcutaneous EGF injection can augment postoperative liver regeneration, however, it might be used only as a prophylactic and not as a therapeutic drug in case of liver insufficiency.

Reduction of peritoneal adhesions by sustained and local administration of epidermal growth factor

Previous studies have shown epidermal growth factor (EGF) facilitate peritoneal membrane healing by augmenting cell adhesion and migration. The objective of this study was to show the effect of sustained and local administration of EGF on peritoneal adhesion. Fourty-two rats were divided into six groups: control 7 and 14, gelatin 7 and 14, and EGF 7 and 14. Adhesions were created by scraping the cecum with mesh gause followed by application of absolute alcohol and placement of silk suture in the parietal peritoneum. The anterior walls of the intestines were covered with 5 x 5 cm unloaded, and EGF loaded gelatin films in the gelatin and EGF groups, respectively. The rats were killed on days 7 and 14 to assess the adhesion occurring, and for biochemical examination. The mean adhesion grades of EGF groups were significantly lower than in the other groups (P < 0.008). The mean adenosine deaminase (ADA) measurements of EGF 7 group were lower than in the gelatin 7 and control 7 groups but the difference was not significant (P > 0.008). The mean ADA measurements in the 14 days groups were as follows: control 14 < EGF 14 < gelatin 14 groups. The mean ADA measurements between 14 days groups did not significantly differ from each other (P > 0.008). The mean hydroxyproline measurements did not differ among the groups (P > 0.008). EGF decreased intestinal adhesion in our study. EGF has important roles in DNA synthesis and cell proliferation. Further studies are required to determine the exact mechanism by which EGF lowers the efficiency of intestinal adhesion.

The effect of sustained and local administration of epidermal growth factor on improving bilateral testicular tissue after torsion

Epidermal growth factor (EGF) modulates Leydig cell proliferation, steroidogenesis, spermiogenesis, and Sertoli cell activity. It plays an important role in repairing ischemia-reperfusion injury in different tissues. The aim of this study was to evaluate the effects of sustained and local administration of EGF on improving bilateral testicular tissue after torsion. A total of 57 Wistar albino rats were used. For the EGF transport system, 1x2 cm gelatin films containing 2 microg EGF were used. Torsion was created by rotating the right testis 720 degrees in a clockwise direction for 4 h in all groups except the control group. Then, in the torsion group, bilateral orchiectomy was performed. After returning the torsioned ipsilateral testes to their normal state, the bilateral testes were wrapped by 1x2 cm unloaded gelatin films in the gelatin (G7 and G21) groups and, by 2 microg EGF loaded gelatin films in the EGF 7 and EGF 21 groups. The testes were removed on the seventh and 21st days, respectively, for biochemical and histological examination. Histologically, Johnsen's spermatogenesis criteria and mean seminiferous tubule diameter (MSTD) measurements were used. The EGF7 group did not show significant loss of Sertoli cells, while in the G7 group the number of these cells decreased. The ipsilateral ischemic testis of the EGF21 group showed Leydig cell hyperplasia, and the contralateral non-ischemic testes in this group were similar to the control group. In the G21 group, the bilateral testes showed Sertoli cell only syndrome in some sections, and most of the cells were undergoing apoptosis. The mean spermatogenesis scores and MSTD in the EGF7 and EGF21 groups were higher than in the G7 and G21 groups ( P<0.05). Malondialdehyde levels were significantly lower in the EGF groups than in the G groups ( P<0.05). Glutathione peroxidase (GSH-Px) levels in the G21 group were significantly higher than in the EGF21 group. Our study shows that local and sustained EGF release after testicular torsion improves bilateral testicular injury. EGF administration may be a new treatment choice for bilaterally injured testis after detorsion without removing the twisted testis.

The effect of epidermal growth factor on the incremental Young's moduli in the rat small intestine

Biomechanical remodelling of the rat small intestine after treatment with epidermal growth factor (EGF) subcutaneously for 2 days (n=6), 4 days (n=6), 7 days (n=6), and 14 days (n=4) was studied. The incremental circumferential, longitudinal and cross moduli close to the in vivo state were computed from bi-axial test data (combined inflation and axial stretching) by a least square method. The moduli in the circumferential direction and the longitudinal direction differed in all groups, i.e. the mechanical properties were anisotropic in both normal and EGF-treated rats. Time-dependent variation existed for the Young's moduli in all directions during EGF treatment (P<0.05). The circumferential modulus decreased during the first 7 days of EGF treatment and it almost remodelled back to that of the control group after 14 days treatment. The incremental modulus in the circumferential direction ranged between 17.4 and 24.2 kPa. The modulus in the longitudinal direction ranged between 22.9 and 32.4 kPa. The longitudinal modulus after 4 days EGF treatment was significantly larger than that of control group (P<0.02). The cross modulus decreased during the first 4 days of EGF treatment thereafter it increased to a maximum at 7 days. The values for the cross moduli were between 4.7 and 6.6 kPa. In conclusion, the mechanical properties in the intestinal wall are anisotropic and remodel during treatment with EGF.

Increased expression of epidermal growth factor receptors in basal cell hyperplasia of the oesophagus after acid reflux oesophagitis in rats

BACKGROUND

Epidermal growth factor (EGF), which binds to EGF receptors (EGF-R), stimulates oesophageal epithelial cell proliferation, enabling rapid repair after mucosal injury. In the normal human oesophageal epithelium, EGF-R expression is present and confined to the basal layer.

AIM

To examine histological changes in and dynamics of EGF-R expression during healing after acid reflux oesophagitis in a rat model.

METHODS

Gastric acid reflux oesophagitis was induced in Wistar rats by ligation of the pylorus and the transitional region between the forestomach and the grandular portion for 5 h, followed by release of both ligations. Rats were killed 7 and 14 days after production of oesophagitis to examine macroscopic and histological changes as well as dynamics of EGF-R expression. Epithelial cell proliferation was assessed by bromodeoxyuridine (BrdU) uptake, and expression of EGF-R mRNA and protein by RT-PCR and Western blotting or immunohistochemistry.

RESULTS

Gastric acid reflux induced erosive and ulcerative mucosal lesions in the lower and middle part of the oesophagus. These lesions were healed by 14 days and histologically showed thickening of the oesophageal epithelium from 41.11 +/- 3.09 microm in controls to 142.73 +/- 11.59 microm (P < 0.001) in ligated rats, as well as elongation of papillae and basal cell hyperplasia. The number of BrdU-positive cells among basal cells on day 14 was significantly increased from 7.1 +/- 0.8/field in controls to 30.9 +/- 3.0/field in ligated rats. Expression of EGF-R mRNA and protein was significantly increased on day 14 and most basal cells were immunohistochemically positive in both BrdU and EGF-R staining.

CONCLUSION

Acid reflux-induced oesophageal injury caused basal cell hyperplasia with an increase in cell proliferation and EGF-R expression. Activation of EGF-R gene and protein in response to acid reflux-induced injury may facilitate mucosal healing. These results suggest that epidermal growth factor receptors play a crucial role in healing after acid reflux oesophagitis in rats.

Effects of caffeic acid phenethyl ester and epidermal growth factor on the development of caustic esophageal stricture in rats

BACKGROUND/PURPOSE

An experimental study was performed to modify the healing response in caustic esophageal burns to prevent stricture development. Two different agents with different modes of actions, caffeic acid phenethyl ester (CAPE) and epidermal growth factor (EGF), were studied. CAPE has antiinflammatory, immunomodulatory, antioxidant, and antimitotic properties. EGF has known properties in supporting wound healing and in protecting esophagus from injuries.

METHODS

The model described by Gehanno and its modification by Liu was used to create standard esophageal burns with 50% NaOH. The study was performed with 76 rats in 4 main groups (sham, CAPE, EGF, and control) and 2 subgroups in each for 5 and 28 days of observation. Efficacy of treatment was assessed in 28-day subgroups by measuring weight gain, contrast esophagograms on day 27, histologic evaluation by measuring stenosis index (wall thickness/lumen diameter), and collagen deposition, and biochemically by determining tissue hydroxy proline (OHP) content.

RESULTS

In the end of the study, increase rates of mean body weights of the animals in the 28-day subgroups were as follows: sham, 30%; CAPE, 23%; EGF, 22%; and control, 14%. Although all the animals in subgroups significantly gained weight, the mean weight gain was significantly low in controls when compared with sham, CAPE, and EGF groups (P <.05). Contrast esophagograms on day 27 showed no stenosis in the sham, mild stenosis in CAPE and EGF, and severe stenosis with proximal dilatation in controls. Stenosis indices of the subgroups were as follows: sham, 0.29; CAPE, 0.41; EGF, 0.41; control, 0.84. Index was significantly higher in controls (P <.05). Collagen accumulation scores in the esophageal wall were as follows: Sham, 0.0; CAPE, 0.87; EGF, 0.30; control, 2.70. Scores also were significantly higher in controls (P <.05). Tissue (OHP) levels were as follows (mg/g dry tissue): Sham, 1.48; CAPE, 1.53; EGF, 1.90; control, 4.01. Production of OHP was significantly higher in controls.

CONCLUSIONS

The results of the parameters in the study indicate that administration of CAPE and EGF has beneficial effects in the prevention of caustic esophageal strictures. Those effects of CAPE may occur through its antiinflammatory, immunomodulatory, and antioxidant properties, and EGF may occur through its induced proliferative properties on the esophagus.

Time-dependent changes in the luminal surface and mass of the rat colon during prolonged systemic treatment with epidermal growth factor

BACKGROUND

Systemic treatment with epidermal growth factor (EGF) for 4 weeks increases the colonic mucosal weight and surface area. The present study was initiated to describe the time-dependent colonic changes during prolonged treatment with EGF.

METHODS

Forty-eight female Wistar rats were allocated into five groups receiving subcutaneous EGF treatment (150 microg/kg/day) for 0 (controls), 1, 2, 3, or 4 weeks. EGF was administered in the weeks before they were killed. By means of modern stereologic techniques (point counting and vertical sections), the weights of the colonic wall layers and the luminal surface area were measured on histologic sections. The colon was subdivided into proximal and distal parts.

RESULTS

The weight of the total colon increased relatively more than the total body weight. After 1 week of treatment with EGF the surface area and wet weight of the total colon increased by 47% and 10%, and after 4 weeks by 62% and 37%, respectively. After 4 weeks the weight increase was mainly due to increased mucosal weight (by 65%, P < 0.01) and less prominently the submucosa (by 45%, P < 0.01) and the muscularis propria (by 32%, P < 0.01). On the basis of the wet weight increase, the proximal colon was more responsive to EGF treatment than the distal colon.

CONCLUSIONS

Systemic treatment with EGF for 1 week increased the luminal surface area relatively more than the mass of the colon. Treatment with EGF for more than 1 week caused only a minor further surface area increase, whereas the colonic mass continued to increase in a time-dependent manner.

Role of growth factors in oesophageal mucosal healing: A work in progress

Reflux of gastroduodenal contents into the oesophagus results in dynamic cycles of injury followed by cell proliferation and repair. These processes are receiving increased attention due to the high incidence of gastro-oesophageal reflux disease and the rising incidence of adenocarcinoma of the oesophagus. Repeated cycles of injury and repair may lead to abnormal differentiation followed by abnormal growth. This article summarizes the research performed by our group in the field of oesophageal injury and repair. We initially developed an in vivo perfused rabbit oesophagus model that served to study the effects of various components of the gastroduodenal juice on several parameters of oesophageal injury. We have shown that pepsin causes severe morphological oesophagitis at an acidic pH but is ineffective at an alkaline pH. We have also demonstrated that trypsin causes severe morphological oesophagitis at an alkaline pH but not at an acidic pH. Bile salts were found to disrupt the oesophageal barrier at both pH levels. We have also studied the effects of epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I) on oesophageal regeneration. We used an ex vivo oesophageal explant model for these experiments. Both EGF and IGF-I cause a dose-dependent increase in oesophageal DNA synthesis, cell proliferation and mucosal growth. These effects are synergistic and can be inhibited by specific tyrphostins. We are currently studying the role of growth factors as therapeutic agents and the role of growth factors in the development of Barrett's oesophagus and adenocarcinoma.

The effects of chronic administration of epidermal growth factor (EGF) to rats on the levels of endogenous EGF in the submandibular glands and kidneys

Epidermal growth factor (EGF) is mainly produced in the submandibular glands (SMG) and in the kidneys. It has recently been reported that EGF-related ligands may induce their own biosynthesis (autoinduction) in vitro. In the present paper, we investigated whether chronic systemic treatment with EGF influenced the amount of endogenous EGF in the SMG and kidneys. Eight-week-old female Wistar rats were treated with subcutaneous injections of placebo (n = 16) or human recombinant EGF (150 micrograms/kg per day, n = 8) for 4 weeks. Urine was sampled the last 24 h of the study period. At the time of killing, the SMG and the kidneys were removed. The SMG was larger in the EGF-treated animals, 229.8 +/- 35.5 (mean +/- SD) mg than in the control animals, 181.7 +/- 18.1 mg (P < 0.01). The total EGF content was smaller (0.51 +/- 0.15 vs. 1.12 +/- 0.40 nmol EGF/SMG, P < 0.001). The kidneys were larger in the EGF-treated animals (1.38 +/- 0.08 vs. 1.28 +/- 0.08 g, P < 0.05), but the EGF content and urinary excretions were not changed. In conclusion, chronic systemic treatment with EGF causes growth of the SMG with concomitantly reduced contents of EGF, and growth of the kidneys with unchanged content and excretion of EGF. These findings suggest that EGF may play a part in the regulation of the growth of the SMG and in EGF biosynthesis.

Systemic treatment with epidermal growth factor in the rat. Biomechanical properties of the growing small intestine

Prolonged treatment with epidermal growth factor (EGF) in the rat provides an experimental model to growth of the gastrointestinal tract. We treated female Wistar rats for 0 (n = 15), 1 (n = 8), 2 (n = 8), and 4 (n = 8) weeks with subcutaneous EGF (i50 micrograms.kg-1.day-1). Segments were taken from locations at 10, 50 and 90% along the length of the small intestine, weighed, the wall thickness was measured and the luminal cross-sectional area and passive biomechanical properties were assessed using impedance planimetry. In addition, the wall composition was evaluated on histological sections. The weight of the total small intestine and of the three segments (measured in mg.cm-1) increased with the duration of the EGF treatment due to mucosal and muscular growth. After 1 week of treatment the wall thickness increased. After 2 weeks of treatment the cross-sectional area began to increase. The circumferential stress-strain distributions revealed translation of the curves to the right in the graphs implying reduced wall stiffness during EGF treatment. In conclusion EGF treatment for 1 to 4 weeks caused a time-dependent increase in intestinal weight. The growth was characterized by increased wall thickness, increased cross-sectional area and reduced wall stiffness.

Chronic systemic treatment with epidermal growth factor in the rat increases the mucosal surface of the small intestine

We examined the effects of treatment with human recombinant epidermal growth factor (EGF) on the functioning small intestine in the rat. Male Wistar rats, 7-8 weeks old, were treated with EGF administered subcutaneously in doses of 0 (n = 7) or 150 micrograms/kg/day (n = 8) for 4 weeks. The histological composition and mucosal surface area of the perfusion-fixed small intestine was quantified with stereological principles. The length of the gut remained unchanged. The amount of tissue and surface area per length of gut (median (ranges)) were increased from 117 (101-131) mg/cm and 2.6 (2.1-3.5) cm2/cm in the controls to 146 (138-152) mg/cm and 3.5 (2.5-3.8) cm2/cm for the complete small intestine (both comparisons P < 0.02). The weight increase was due to mucosal growth in all parts of the intestine, whereas the surface area was only increased in proximal and middle parts. It is concluded that EGF treatment in rats increases the mucosal weight and surface area of the functioning small intestine.

Chronic treatment with epidermal growth factor causes esophageal epithelial hyperplasia in pigs and rats

Epidermal growth factor (EGF) is an important factor for maintaining the esophageal functional integrity. Goettingen minipigs were treated with either placebo or subcutaneous EGF (30 micrograms/kg/day) for four weeks. Wistar rats were treated with either placebo or subcutaneous EGF (150 micrograms/kg/day) for four weeks. At sacrifice, esophageal samples were obtained for histology, immunochemistry, and lectin characterization. In pigs, the thickness of the esophageal epithelium was almost doubled in the EGF-treated animals. Characterization with lectins revealed a normal pattern of differentiation. Subcutaneously administered EGF was visualized on cells located basally in the esophageal epithelium. In rats, EGF-treatment increased the esophageal volume of the epithelium, the lamina propria of the mucosa, and the submucosa. In conclusion, systemic EGF challenge induces growth of the esophageal epithelium with an unaltered pattern of differentiation. This supports previous studies demonstrating a beneficial effects of systemic EGF-treatment on sclerotherapy-induced esophageal damage.