Heparin-binding epidermal growth factor (HB-EGF) may improve embryonic development and implantation by increasing vitronectin receptor (integrin alphanubeta3) expression in peri-implantation mouse embryos

PURPOSE

This study investigated the effects of HB-EGF on expression of integrin alphanubeta3 and implantation of embryos.

METHODS

Two-cell embryos were recovered and cultured with or without 10 ng/mL HB-EGF for 96h. Expression of integrin alphanubeta3 in cultured embryos was examined by real time-RT-PCR and immunofluorescence analysis; embryos were cultured with or without HB-EGF, then transferred into the uteri of pseudo-pregnant female mice in order to analyze their implantation rate.

RESULTS

HB-EGF improved embryonic hatching and outgrowth during extended culture, and up-regulated expression of integrin alphanubeta3 in both the preimplantation embryo and outgrowing blastocyst. Also, integrin alphanubeta3 subunits were localized at the pericellular borders and cell-cell contact areas. The number of successful implantation sites of transferred HB-EGF-treated embryos in the uterus was increased when compared to number of implantation sites with non-treated controls.

CONCLUSIONS

HB-EGF may improve implantation by accelerating expression of integrin alphanubeta3 in peri-implantation mouse embryos.

Heparin-binding epidermal growth factor-like growth factor reduces intestinal apoptosis in neonatal rats with necrotizing enterocolitis

PURPOSE

We have previously demonstrated that enterally administered heparin-binding epidermal growth factor-like growth factor (HB-EGF) decreases the incidence and severity of necrotizing enterocolitis (NEC) in a neonatal rat model. Because apoptosis contributes to gut barrier failure in this model, the aim of this study was to investigate the effect of HB-EGF on apoptosis during the development of NEC.

METHODS

NEC was induced in neonatal rats by exposure to hypoxia, hypothermia, hypertonic formula feeding (HHHTF) plus enteral administration of lipopolysaccharide (LPS). Fifty-one neonatal rats were randomly divided into the following groups: (1) breast-fed (BF), (2) HHHTF + LPS, and (3) HHHTF + LPS with HB-EGF (600 microg/kg) added to the formula. NEC was evaluated using a standard histological scoring system. Apoptotic cells in intestinal tissues were detected by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) and by active caspase 3 immunohistochemical staining.

RESULTS

The incidence of NEC in the HHHTF + LPS group was higher than that in the BF group (65% vs 0%, P < .05). With administration of HB-EGF, the incidence of NEC significantly decreased to 23.8% (P < .05). The median TUNEL and active caspase 3 scores in the HHHTF + LPS group were higher than those in the BF group (1.9 vs 0.9 and 1.75 vs 0.6, respectively, P < .05). The median TUNEL and active caspase 3 scores were significantly decreased in the HHHTF + LPS + HB-EGF group compared with the HHHTF + LPS group (1.24 vs 1.9 and 1.0 vs 1.75, respectively, P < .05).

CONCLUSION

HB-EGF reduces the incidence of NEC in a neonatal rat model in part by decreasing apoptosis. These results support the use of HB-EGF-based clinical regimens for the treatment of NEC.

[Recombinant human epithelial growth factor accelerates healing of cervical erosion]

OBJECTIVE

To observe the effect of recombinant human epithelial growth factor (rhEGF) in promoting the healing of cervical erosion.

METHODS

Forty-eight patients with cervical erosion were treated with rhEGF and 30 with 500 kHz high-frequency electromagnetic wave, and the effects of the therapies were compared in terms of healing of the cervical wound, healing time, volume of vaginal discharge and bleeding and the lasting time.

RESULTS

In comparison with radiofrequency therapy, the healing of the lesion took significantly shorter time with rhEGF therapy, which also resulted in less vaginal discharge that lasted for shorter time without causing vaginal bleeding.

CONCLUSION

rhEGF can obviously accelerate the healing of cervical erosion.

Effects of interleukin-11 and epidermal growth factor on residual small intestine after experimental massive small bowel resection

Interleukin 11 (IL-11) is a multifunctional cytokine derived from bone marrow, which has a trophic effect on small bowel epithelium. This study compares the effects of IL-11 with epidermal growth factor (EGF), a growth factor known to enhance small bowel adaptation. Forty Sprague-Dawley rats (90-100g) underwent an 85% mid-small bowel resection with primary anastomosis on day 0. Rats were divided into four treatment groups: controls (group I) received bovine serum albumin (BSA), group II received IL-11, 125 microg/kg subcutaneously (SC) twice daily, group III received EGF, 0,10 microg/g SC bid, and group IV received EGF and IL-11 in the above doses. Half of the animals (five per group) were killed on day 4 of therapy, and the rest on day 8. Animals were evaluated for weight, mucosal length, and bowel wall muscle thickness on days 4 and 8, and expression of proliferating cell nuclear antigen (PCNA) in intestinal crypt and smooth muscle cells on day 8. Body weight was similar at day 4 and 8. Mucosal thickness in groups 11 (IL-11) and IV (IL-11 and EGF) was significantly increased at day 4 and 8 compared with controls (group I) and EGF (group III, P<.001). Muscle thickness was significantly increased in the EGF and combined group IV compared with the BSA controls and IL-11 groups (P < .001). Thirty-two percent of the mucosal crypt cells in group I stained positive for PCNA, whereas 51%, 53%, and 60% stained positive in groups II (IL-11), III (EGF), and IV (IL-11 and EGF), respectively. In groups I and II, 2% and 1.7% of the myocytes stained positive for PCNA, whereas 11.2% and 5.2% in group III and IV. These data suggest that IL-11 has a trophic effect on small intestinal enterocytes, causing cell proliferation and increased mucosal thickness. EGF has a more generalized effect causing proliferation of both enterocytes and myocytes. IL-11, with or without EGF may be a useful adjunct in treatment of short bowel syndrome.

Influence of EGF/bFGF treatment on proliferation, early neurogenesis and infarct volume after transient focal ischemia

The persistence of neurogenesis in the adult mammalian forebrain suggests that endogenous precursors may be a potential source for neuronal replacement after injury or neurodegeneration. On the other hand basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) can facilitate neural precursor proliferation in the adult rodent subventricular zone (SVZ) and dentate gyrus. As the application of EGF and bFGF was found to boost neurogenesis after global ischemia, in this study we investigated whether a combined intracerebroventricular (i.c.v.) EGF/bFGF treatment over a period of 2 weeks affects the proliferation of newly generated cells in the endothelin-1 model of transient focal ischemia in adult male Sprague-Dawley rats as well. As assessed by toluidine blue staining, EGF/bFGF substantially increased the infarct volume in ischemic animals. Chronic 5'-bromodeoxyuridine (BrdU) i.c.v. application revealed an EGF/bFGF-induced increase in cell proliferation in the lateral ventricle 14 days after surgery. Proliferation in the striatum increased after ischemia, whereas in the dentate gyrus and in the dorsal 3rd ventricle the number of cells decreased. Analysis of the neuronal fate of these cells by co-staining with a doublecortin (DCX) antibody showed that the growth factors concomitantly nearly doubled early neurogenesis in the ipsilateral striatum in ischemic animals but diminished it in the dentate gyrus. Because of the increased infarct volume and unclear long-term outcome further modifications of a chronic treatment schedule are needed before final conclusions concerning the perspectives of such an approach can be made.

Mechanisms of disease: Radiosensitization by epidermal growth factor receptor inhibitors

The epidermal growth factor receptor (EGFR) inhibitors are among the most intensely studied new molecular therapeutic agents. Although response rates have been somewhat disappointing when EGFR inhibitors are used as single-agent therapy for advanced disease, these inhibitors may be more effective as chemo- and radiosensitizers. The first phase III randomized trial evaluating EGFR inhibitors as radiosensitizers in patients with locally advanced head and neck cancer was strongly positive, indicating significant potential of this class of agents to improve outcome with radiotherapy. However, optimal implementation of EGFR inhibitors as radiosensitizers depends, in part, on a better understanding of the mechanisms of radiosensitization. Preclinical studies provide important observations with regard to potential mechanisms. The phenotypic cellular changes associated with EGFR inhibition are impressively consistent between different model systems, with almost all studies showing that EGFR inhibitors affect proliferation, angiogenesis, and cell survival. Whether EGFR inhibitors influence response to radiation directly, or whether the improved response is a result of additive effects of the two modalities, remains unclear. However, cell-cycle arrest, endothelial cell sensitivity, and apoptotic potential are all important factors in radiation response of epithelial tumors. Furthermore, less-studied effects of EGFR inhibitors on DNA repair suggest that modulation of DNA damage response to cytotoxic injury might result in radio- or chemosensitization. This review will explore potential mechanisms of radiosensitization by EGFR inhibitors.

Epidermal growth factor reduces hepatic sequelae in experimental necrotizing enterocolitis

BACKGROUND AND AIM

Neonatal necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of premature infants. We recently demonstrated that the gut/liver axis plays an important role in the pathophysiology of NEC through the release of inflammatory mediators into the intestinal lumen. We have also shown that supplementation of formula with epidermal growth factor (EGF) dramatically decreases ileal pathology associated with experimental NEC. In this study, we examined the effects of EGF on the liver portion of the gut/liver axis in the neonatal rat model of NEC.

METHODS

Newborn rats were divided into three experimental groups, NEC, hand-fed with growth-factor free formula; NEC + EGF, hand-fed with formula supplemented with 500 ng/ml rat EGF; or DF, dam fed. All animals were exposed to asphyxia and cold stress twice daily for 4 days to develop NEC.

RESULTS

EGF receptor expression was significantly (p <or= 0.01) decreased in the NEC+EGF group compared to the NEC group. EGF supplementation significantly decreased Kupffer cell numbers (p <or= 0.01) as well as hepatic tumor necrosis factor (TNF)-alpha and interleukin-18 production (p <or= 0.05). Further, TNF-alpha in the intestinal luminal contents of the NEC+EGF group were normalized to levels observed in DF controls compared to the NEC group (p <or= 0.05). Activated nuclear factor-kappaB was also substantially decreased in the NEC+EGF group versus the NEC group.

CONCLUSION

The results of this study indicate that EGF normalizes cytokine overproduction in the liver of neonatal rats with NEC, which contributes to diminished intestinal damage during the development of experimental NEC. These data suggest that supplementation of formula with EGF can have beneficial effects on the gut/liver axis during NEC pathogenesis.

Enhancing dermal matrix regeneration and biomechanical properties of 2nd degree-burn wounds by EGF-impregnated collagen sponge dressing

To better define the relationship between dermal regeneration and wound contraction and scar formation, the effects of epidermal growth factor (EGF) loaded in collagen sponge matrix on the fibroblast cell proliferation rate and the dermal mechanical strength were investigated. Collagen sponges with acid-soluble fraction of pig skin were prepared and incorporated with EGF at 0, 4, and 8 microg/1.7 cm2. Dermal fibroblasts were cultured to 80% confluence using DMEM, treated with the samples submerged, and the cell viability was estimated using MTT assay. A deep, 2nd degree- burn of diameter 1cm was prepared on the rabbit ear and the tested dressings were applied twice during the 15-day, post burn period. The processes of re-epithelialization and dermal regeneration were investigated until the complete wound closure day and histological analysis was performed with H-E staining. EGF increased the fibroblast cell proliferation rate. The histology showed well developed, weave-like collagen bundles and fibroblasts in EGF-treated wounds while open wounds showed irregular collagen bundles and impaired fibroblast growth. The breaking strength (944.1 +/- 35.6 vs. 411.5 +/- 57.0 Fmax, gmm(-2)) and skin resilience (11.3 +/- 1.4 vs. 6.5 +/- 0.6 mJ/mm2) were significantly increased with EGF-treated wounds as compared with open wounds, suggesting that EGF enhanced the dermal matrix formation and improved the wound mechanical strength. In conclusion, EGF-improved dermal matrix formation is related with a lower wound contraction rate. The impaired dermal regeneration observed in the open wounds could contribute to the formation of wound contraction and scar tissue development. An extraneous supply of EGF in the collagen dressing on deep, 2nd degree-burns enhanced the dermal matrix formation.

E1-INT (Transition Therapeutics/Novo Nordisk)

Transition Therapeutics (through its acquisition of Waratah Pharmaceuticals), in collaboration with Novo Nordisk, is developing E1-INT, an injectable islet neogenesis therapy comprising an epidermal growth factor analog and a gastrin analog, for the treatment of insulin-dependent (type 1) and non-insulin-dependent (type 2) diabetes. The compound is currently undergoing phase II clinical trials.

Rational design of an EGF-IL18 fusion protein: implication for developing tumor therapeutics

Interleukin-18 (IL-18) is a proinflammatory cytokine. This protein has a role in regulating immune responses and exhibits significant anti-tumor activities. Epidermal growth factor (EGF) is an important growth factor that plays a central role in the regulation of cell cycle and differentiation. It was proposed that a targeted delivery of IL-18 by generation of IL-18-EGF fusion protein might decrease adverse effects and result in enhancing cytotoxic and antitumor activities. In the present study, a fusion protein, consisting of EGFR binding domain fused to human IL-18 mature peptide via a linker peptide of (Gly(4)Ser) 3, was constructed and expressed in the insect cell line Sf9 using Bac-to-Bac baculovirus expression system. We showed that the purified recombinant fusion protein induced similar levels of IFN-gamma to that of native IL-18 protein in human PBMC in the presence of ConA. Furthermore, EGF receptor competitive test in human epithelial cancer A431 cell line showed that EGF-IL18 fusion protein can specifically bind with EGFR by competing with native EGF protein. These suggest that this rationally designed protein can be further developed as novel tumor therapeutics.

[Radiobiological effect of 131I radiolabeled recombinant human epidermal growth factor on nude mice with human breast cancer]

The radiobiological effect of 131I radiolabeled recombinant human epidermal growth factor (131I-rhEGF) on nude mice with human breast cancer was assessed in this study. The tissue mainly uptaking 131I-rhEGF was found by tissue distribution assay in mice. The radiation breakdown of the tissue greatly collecting 131I-rhEGF was examined by biochemical test and biopsy in nude mice with human breast cancer. The tissue distribution assay of 131I-rhEGF in mice showed that 131I-rhEGF greatly accumulated in kidney, liver, spleen and blood. The biochemical test and biopsy revealed that 131I -rhEGF injected twice (dosing once is analogous to 14.58 GBq in a person with 50 kg, once every 14 days) had an effective killing effect on tumor but had no effect of radiation breakdown on kidney, liver,spleen and blood-cell forming tissue in mice with human breast cancer. Therefore, 131I-rhEGF is a drug unharmful to normal tissues in the course of the receptor-mediated target radiotherapy for breast cancer.

Heparin-binding EGF-like growth factor (HB-EGF) and necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a common and devastating gastrointestinal disease that occurs predominantly in premature infants. Despite various advances in management, the mortality of this disease remains high. During the last decade, studies from our laboratory have shown that heparin-binding epidermal growth factor-like growth factor (HB-EGF), a member of the epidermal growth factor (EGF) family, can protect intestinal epithelial cells (IEC) from various forms of injury in vitro. Furthermore, we have used both an intestinal I/R injury model in adult rats, and a neonatal rat pup model of NEC, to show that HB-EGF can protect the intestines from injury. On administration of HB-EGF in the neonatal rat model, the incidence of NEC is reduced from 65% to 27.3% (P < 0.05), and the histological injury score is decreased from 2 to 1.1 (P < 0.05). In addition, the survival rate is increased from 25% to 63.6% and the survival time extended from 59 hours to 73 hours (P < 0.05). In addition, using human specimens from newborns undergoing bowel resection for NEC, we found that the expression of endogenous HB-EGF mRNA in normal areas of the intestine at the resection margins was higher than that of the intestine afflicted with acute NEC. Endogenous HB-EGF may be involved in epithelial cell repair, proliferation, and regeneration during recovery from injury. Exogenous administration of HB-EGF potentiates recovery from intestinal injury in vitro and in vivo. Taken together, these results support a potential therapeutic role for HB-EGF in the treatment of NEC in the future.

A pilot study of the use of epidermal growth factor in pediatric short bowel syndrome

BACKGROUND

This study examined the effects of enterally administered epidermal growth factor (EGF) on nutrient absorption and tolerance of enteral feeds in pediatric patients with short bowel syndrome (SBS).

METHODS

Patients identified with severe SBS (<25% bowel length predicted for age) were prospectively enrolled in treatment using human recombinant EGF (1-53); 100 microg/kg per day given mixed with enteral feeds and patients were treated for 6 weeks. End points followed were patient weight, tolerance of enteral feeds, nutrient absorption, and intestinal permeability as determined using carbohydrate probes and hematologic values for liver function parameters.

RESULTS

Five patients were treated with EGF; all showed a significant improvement in carbohydrate absorption (3-0 methylglucose): absorption 24.7% +/- 9.7% pretreatment vs 34.1% +/- 13.8% posttreatment and improved tolerance of enteral feeds (enteral energy as % of total energy, 25% +/- 28% pretreatment vs 36% +/- 24% posttreatment; mean +/- SD; P < .05 by Wilcoxon's signed rank test). Epidermal growth factor treatment was not associated with significant changes in intestinal permeability, the rate of weight gain, or liver function tests. During the treatment phase, no patients developed episodes of sepsis; however, within 2 weeks of discontinuation of EGF treatment, 3 patients developed septic episodes. No adverse effects of EGF administration were noted.

CONCLUSIONS

These results suggest that enteral treatment with EGF in pediatric SBS improves nutrient absorption, increases tolerance with enteral feeds, and may improve the infection rate. Further studies exploring treatment strategies including the timing and duration of EGF administration are indicated.

Adenovirus-Mediated Gene Transfer of Heparin-Binding Epidermal Growth Factor-Like Growth Factor Enhances Neurogenesis and Angiogenesis After Focal Cerebral Ischemia in Rats

Background and Purpose— Recent studies have demonstrated that neurotrophic factors promote neurogenesis after cerebral ischemia. However, it remains unknown whether administration of genes encoding those factors could promote neural regeneration in the striatum and functional recovery. Here, we examined the efficacy of intraventricular injection of a recombinant adenovirus-expressing heparin-binding epidermal growth factor-like growth factor (HB-EGF) on neurogenesis, angiogenesis, and functional outcome after focal cerebral ischemia.

Methods— Transient focal ischemia was induced by middle cerebral artery occlusion (MCAO) for 80 minutes with a nylon filament in Wistar rats. Three days after MCAO, either adenovirus-expressing HB-EGF (Ad-HB-EGF) or Ad-LacZ, the control vector, was injected into the lateral ventricle on the ischemic side. Bromodeoxyuridine (BrdU) was injected intraperitoneally twice daily on the sixth and seventh days. On the eighth or 28th day after MCAO, we evaluated infarct volume, neurogenesis, and angiogenesis histologically. Neurological outcome was serially evaluated by the rotarod test after MCAO.

Results— There was no significant difference in infarct volume between the 2 groups. Treatment with Ad-HB-EGF significantly increased the number of BrdU-positive cells in the subventricular zone on the 8th day. In addition, on the 28th day, BrdU-positive cells differentiated into mature neurons in the striatum on the ischemic side but seldom the cells given Ad-LacZ. Enhancement of angiogenesis at the peri-infarct striatum was also observed on the eighth day in Ad-HB-EGF–treated rats. Treatment with Ad-HB-EGF significantly enhanced functional recovery after MCAO.

Conclusions— Our data suggest that gene therapy using Ad-HB-EGF contributes to functional recovery after ischemic stroke by promoting neurogenesis and angiogenesis.

Interstitial diphtheria toxin-epidermal growth factor fusion protein therapy produces regressions of subcutaneous human glioblastoma multiforme tumors in athymic nude mice

PURPOSE

The novel fusion protein, DAB389EGF, composed of the catalytic and translocation domains of diphtheria toxin (DAB389) fused with a His-Ala linker to human epidermal growth factor (EGF) was tested for antiglioma efficacy in an in vivo model of human glioma.

EXPERIMENTAL DESIGN

Female athymic nude mice (ages 4-6 weeks) were inoculated s.c. with 10 million U87MG human glioma cells in the right flank. When tumor volumes reached approximately 100 mm3 (approximately 6-8 days), i.t. injections of saline, DAB389IL2, or DAB389EGF 1, 3, 5 or 10 microg in 50 microL were given every other day for three to six doses. Animals were monitored twice daily and tumor measurements were made by calipers.

RESULTS

The maximal tolerated dose (MTD) of DAB389EGF was 3 microg every other day. Above the MTD, animals experienced loss of activity, reduced oral intake, and dehydration. Blood chemistries confirmed elevated blood urea nitrogen, creatinine, aspartate transaminase, and alanine transaminase. Histopathology revealed renal tubular necrosis. At the MTD, tumor regression was seen in all animals. Relapses occurred in 4 of 16 (25%) of animals after 1 month. These tumors contained EGF receptor, were sensitive in vitro to DAB389EGF, and responded to a second course of i.t. DAB389EGF.

CONCLUSIONS

DAB389EGF fusion protein shows in vivo antiglioma efficacy in a s.c. tumor model and warrants further preclinical testing in an i.c. tumor model for eventual treatment of patients with recurrent or refractory EGF receptor-positive glioblastoma multiforme.

[Experimental study of targeting therapy of breast cancer with 131I-labeled epidermal growth factor]

OBJECTIVE

To investigate the effectiveness of (131)I-epidermal growth factor (EGF) on the proliferation of a heterologous graft in nude mice bearing human breast infiltrating duct carcinoma.

METHODS

EGF/HAS was labeled with (131)I by chloramines-T method. Human breast cancer xenografts with positive EGFR expression were established in nude mice. The nude mice were injected with normal saline, Epirubicin Hydrochloride, (131)I-EGF, (131)I-HAS, (131)I intravenously and (131)I-EGF intratumoral administration respectively. The tumor growth inhibition rate was determined by measurement of tumor volume. Different examinations were carried out.

RESULTS

There was remarkable significant difference of tumor volumes at 26th day among (131)I-EGF trial groups, (131)I, (131)I-HAS, and the negative control group. The tumor growth inhibition rate of (131)I-EGF trial groups was 82.0%, 80.7% respectively. Compared with the negative control group, the (131)I-EGF trial groups remarkably suppressed the growth of tumor (P < 0.05). Irreversible destruction of tissues in (131)I-EGF groups was observed under light and electron microscope. There was no evidence of hepatotoxicity, renal toxicity and myelotoxicity in nude mice bearing human breast cancer given (131)I-EGF over a 4-wk observation period.

CONCLUSION

(131)I-EGF has obvious antitumor effects on a heterologous graft in nude mice bearing human breast infiltrating duct carcinoma, with little obvious side effects.

Medical therapy for ulcerative colitis: the state of the art and beyond

Ulcerative colitis (UC) is an idiopathic inflammatory condition of the large intestine. Recent advances in our understanding of the pathogenesis of UC have led to the development of novel treatments for this often debilitating condition. Aside from aminosalicylates and corticosteroids, drugs that have been used for decades in the treatment of UC, biologic agents, in addition to medications targeting specific effector mechanisms involved in the inflammatory cascade, have been used in patients with UC with varying degrees of success. Clinicians have never had as many therapeutic options for UC as they do today. Herein we review the variety of treatment options, both standard and investigational, that are available for patients with UC.

[Growth factors and wound healing: review and prospect in recent ten years]

OBJECTIVE

To review the current condition of growth factors and their application to clinical treatment of acute and chronic wounds.

METHODS

Data from the literature and Medline were analyzed according to their different uses in acute and chronic wounds. Their potential side-effects were studied.

RESULTS

All data showed that wound healing time in acute and chronic wounds was accelerated and wound healing quality was improved after treatment with growth factors. No side-effect was observed.

CONCLUSION

The efficacy and safety of growth factors in improving wound healing were confirmed. However, some reconsideration about potential problems of growth factors must be made to apply them clinically in the future.

The use of recombinant human epidermal growth factor (rhEGF) in a gentleman with drug-induced Steven Johnson syndrome

A case of drug-induced Steven Johnson syndrome in a gentleman is reported. Its course of treatment with rhEGF was compared to conventional treatment in historical control.

Topical disposition of two strengths of a 125I-rhEGF jelly in rat skin wounds

Growth factors have proved to be an effective therapeutic strategy. However, some controversies have arisen concerning their efficacy in topical wound treatments. Stabilization of epidermal growth factors at the wound site and long-lasting receptor occupancy are important factors for wound repair. This study evaluated the cumulative profiles of two jellies containing 10 or 20 microg of 125I-rhEGF per gram of jelly, in a rat full-thickness skin lesion model. The prolonged time-courses at the wound sites for both strengths compared with saline solutions previously evaluated using a similar skin lesion model are reported. It seems that these two topical formulations that provide more sustained amounts of 125I-rhEGF over the period of sampling, would probably achieve the required wound healing response in terms of cell proliferation, collagen deposition and protein synthesis. Further studies need to be developed in order to elucidate whether such an in vivo disposition pattern is consistent with an earlier and stronger promotion of wound healing events.

Wound healing: the role of growth factors

Wound healing is a complex biological process that requires cellular interactions between a variety of cells, including fibroblasts, myofibroblasts, smooth muscle cells, endothelial cells, keratinocytes and immune cells. These interactions are mediated by numerous factors such as growth factors, hormones, blood components and second messengers. Several growth factors that are released at the wound site are presumed to be necessary for wound healing. These include epidermal growth factor (EGF), fibroblast growth factor (FGF), insulin-like growth factor (IGF), keratinocyte growth factor (KGF), platelet-derived growth factor (PDGF), transforming growth factor (TGF) and vascular endothelial growth factor (VEGF). The clinical use of growth factors to stimulate the healing of wounds is currently being investigated. Several growth factors, including PDGF, FGF-2, IGF and KGF, have been used in clinical trials, and PDGF is currently approved for use in human medicine.

Effect of epidermal growth factor infusion on fetal rabbit intrauterine growth retardation and small intestinal development

BACKGROUND/PURPOSE

Intrauterine growth retardation (IUGR) infants have impaired gastrointestinal function with resultant feeding difficulties and predisposition to necrotizing enterocolitis. Supplemented amniotic fluid swallowed by the developing fetus is a potential prenatal treatment for IUGR. Rabbits have naturally occurring IUGR fetuses based on uterine position. To determine intestinal response to epidermal growth factor (EGF) infusion, this rabbit model of IUGR was studied.

METHODS

Eight pregnant rabbits underwent placement of intraamniotic catheters into 2 normal and 2 IUGR fetuses per mother on gestational day 24 of a 31-day gestation. Miniosmotic pumps infused either EGF (about 300 microg/kg/d) or control solution forming 4 study groups (EGF-Favored [Fav] v. Cont-Fav; EGF-IUGR v. Cont-IUGR). On gestational day 31, the fetal gastrointestinal tracts were harvested for analysis. Intestinal epithelial cell proliferation was studied by 5-bromo-2-deoxyuridine (BrdU) incorporation, villus heights were measured, and EGF mRNA was measured by reverse transcriptase polymerase chain reaction (RT-PCR). Statistical analysis was performed using Students' t test.

RESULTS

Fetal survival rate was 87%. EGF-IUGR fetal weights were increased compared with Cont-IUGR fetuses. EGF infusion significantly increased IUGR fetal small intestinal villus height and BrdU-positive small intestinal (SI) crypt cells, all approaching Cont-Fav levels. EGF mRNA was expressed throughout the gastrointestinal tract.

CONCLUSIONS

Supplemental amniotic EGF normalizes fetal weight and intestinal proliferation in the IUGR fetal rabbit. The inclusion of EGF in supplemental amniotic feeding solutions is supported.