Tissue-engineered stomach: a preliminary report of a versatile in vivo model with therapeutic potential

Background/Purpose: Microgastria and postgastrectomy morbidities are substantial. The authors hypothesized a functional living tissue-engineered stomach could function as a replacement alternative.Methods: Stomach organoid units, mesenchymal cores surrounded by epithelia, were isolated from neonatal and adult rats and transplanted paratopically on biodegradable polymer tubes, which were implanted in syngeneic hosts, varying the inclusion of stomach regions. Four weeks later, tissue-engineered stomach (TES) was either harvested or anastomosed. GFP labeling was performed before implantation. Histology and immunohistochemical detection of the antigensgastrin and actin smooth muscle were performed.Results: Ninety-eight percent of all animals generated TES, including TES formation from adult tissue. Immunohistochemistry for α-actin smooth muscle and gastrin confirms the presence of a smooth muscle layer and a well-developed gastric epithelium containing all the elements of the native rat stomach including gastric pits and squamous layers, varying by included regions at harvest. TES architecture was maintained in anastomosis: GFP-labeled TES maintained signal in anastomosis, proving the donor origin of the TES.Conclusions: TES resembles native stomach and maintains robust histology in anastomosis, a new versatile model for the study of gastric physiology and possible therapy.     

Dorsoventral patterning in oesophageal atresia with tracheo-oesophageal fistula: Evidence from a new mouse model

Background/Purpose: The well-established Adriamycin rat model of oesophageal atresia (OA) and tracheo-oesophageal fistula (TOF) complements recently described mouse genetic models in which loss of function mutations in foregut patterning genes, such as Nkx2.1 (Ttf 1), lead to OA/TOF. The authors aimed to integrate the 2 systems by adapting the Adriamycin model to the mouse to study molecular aspects of tracheo-oesophageal development. Methods: Pregnant CBA/Ca mice were injected intraperitoneally with 4 mg/kg of Adriamycin on embryonic days 7.5 and 8.5. Embryos and fetuses of various gestational ages were subjected to morphologic or histologic examination. Sections were stained with H [amp ] E or processed for immunohistochemistry using an antibody specific for Nkx2.1. Results: Tracheo-oesophageal malformations were observed in 47% of Adriamycin-treated embryos. Early foregut development was similar in Adriamycin-exposed and control embryos but, by E11.5, many treated embryos had an undivided oesophago-trachea, which gave rise to the lung buds and a fistula to the stomach. The fistula originated from the dorsal aspect of the undivided tube and was negative for Nkx2.1, or showed only transient Nkx2.1 expression, compared to the strongly positive bronchi ventrally. Conclusions: The Adriamycin model of OA is adaptable to the mouse. In the absence of tracheo-oesophageal separation, the dorsal fistula retains its nonrespiratory commitment suggesting that dorsoventral patterning of foregut development is undisturbed by Adriamycin exposure.     

Impaired esophageal reactivity in adriamycin-induced rat esophageal atresia: an in vitro study

PURPOSE: The aim of this study was to investigate the reactivity of lower esophageal smooth muscle in the Adriamycin-induced esophageal atresia (EA) rat model. METHODS: The fetuses were divided into 3 groups. The control group was exposed to saline. The second group comprised fetuses that were exposed to Adriamycin but in whom EA did not develop. The third group comprised of fetuses that were exposed to Adriamycin and EA was observed. The reactivity of distal esophageal strips was studied in organ chambers. RESULTS: The tension was similar in all groups precontracted with carbachol for the study of relaxation to serotonin. Relaxation of lower esophageal strips to serotonin was comparably unaffected in the control and Adriamycin-no EA groups, whereas it was significantly inhibited in the EA group with decreased E(max) and pD(2) values. Contractile responses of esophageal smooth muscle to carbachol or 80 mmol/L KCl and relaxant responses to papaverine were similar in all groups. No change in agonist potency was observed among the groups. CONCLUSIONS: Our study showed impairment of serotonin-receptor-mediated relaxation; but not of cholinoceptor-mediated contraction of the lower esophageal smooth muscle in the EA. Thus, impaired relaxant responses may be, at least in part, a contributing factor in the esophageal dismotility seen in EA.     

Alterations in smooth muscle contractile and cytoskeleton proteins and interstitial cells of Cajal in megacystis microcolon intestinal hypoperistalsis syndrome

Background/Purpose: Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is characterized by decreased or absent peristalsis. Gastrointestinal motility depends on the enteric nervous system, smooth muscle cells (SMCs), and the interstitial cells of Cajal (ICCs). Contractile and cytoskeleton proteinase are important structural and functional components of SMCs. The aim of study was to examine the expression of contractile and cytoskeleton proteins in SMCs and distribution of ICCs in MMIHS bowel. Methods: Full-thickness bowel specimens were obtained from 4 infants with MMIHS and 4 controls. Specimens were processed as whole-mount preparations and frozen and paraffin sections. Combined staining of NADPH-d histochemistry/c-kit immunohistochemistry, single and double immunohistochemistry using [alpha ]-smooth muscle actin ([alpha ]-SMA), calponin (CALP), caldesmon (CALD), desmin (DES), protein gene product 9.5 (PGP 9.5) and c-kit antibodies were performed and examined using light and confocal scanning microscopy. Results: [alpha ]-SMA, CALP, CALD, and DES immunoreactivity were reduced markedly in MMIHS bowel compared with controls. Combined NADPH/c-kit staining showed dense network of ICCs around myenteric plexus in MMIHS bowel. In contrast, the intramuscular ICCs either were absent or reduced in MMIHS bowel. Conclusions: Marked reduction of contractile and cytoskeleton proteins in SMCs combined with reduced expression of intramuscular ICCs in the gut may be responsible for the motility dysfunction in MMIHS. J Pedriatr Surg 38:749-755. [copy ] 2003 Elsevier Inc. All rights reserved.     

Tissue-engineered urinary bladder wall using PLGA mesh-collagen hybrid scaffolds: a comparison study of collagen sponge and gel as a scaffold

Purpose: Tissue engineering of the urinary bladder using autologous cells and biodegradable scaffold is a promising method for augmentation. The authors developed 2 hybrid scaffolds by combining poly (DL-lactic-co-glycolic acid; PLGA) mesh for mechanical strength with collagen sponge or gel suitable for cell seeding. The aim of this study was to compare collagen as a scaffold between collagen sponge and gel and to construct a tissue-engineered urinary bladder wall utilizing these hybrid scaffolds.Methods: The PLGA mesh-collagen hybrid scaffolds were prepared by introducing collagen sponge or gel into the PLGA knitted mesh. Urothelial and smooth muscle cells were obtained from porcine urinary bladder wall and were cultured in their respective media. The cells were seeded on these hybrid scaffolds. These constructs were analyzed morphologically and immunohistochemically.Results: The urothelial layer was generated 3 dimensionally by culturing urothelial cells with PLGA mesh and collagen sponge. The smooth muscle layer was constructed by culturing smooth muscle cells with PLGA mesh and collagen gel. And a novel tissue-engineered urinary bladder wall was constructed laminating the urothelial and smooth muscle layers.Conclusions: Ex vivo construction of urinary bladder wall using hybrid scaffolds prepared by combining PLGA mesh with collagen sponge or gel was successful. This tissue-engineered urinary bladder wall allows easy handling and may become a promising tool for bladder augmentation.     

Effect of L-NAME on decreased ileal muscle contractility induced by peritonitis in rats

Background/Purpose: It is now well established that intestinal inflammation is associated with disturbed contractility. The aim of this study was to determine the effects of peritonitis on longitudinal ileum smooth muscle responses to KCl, carbachol and substance P (SP) and to examine the role of nitric oxide (NO) and N_omega-nitro-L-arginine methylester (L-NAME) on ileal contractility in this peritonitis model. Methods: Peritonitis was induced by cecal ligation and puncture (CLP) in 20 rats. While 10 of these received 1 mL distilled water as placebo, the other 10 received 5 mg/kg (subcutaneously) L-NAME before the operation. Another group of 10 rats underwent a sham operation. Twenty-four hours after the operation, the rats were killed, and their ileum was excised. Ileum segments were placed in longitudinal direction in a 10-mL organ bath; concentration-response relationship for KCl, carbachol, and SP were obtained by adding the reagent cumulatively to the bath. Results: The KCl-, carbachol-, and SP-induced contractions were decreased markedly, with no change in the pD₂ values in the peritonitis group compared with controls. Peritonitis-induced changes in the contractile responses were restored significantly by in vivo L-NAME pretreatment. Conclusions: The model of CLP-induced peritonitis in rats showed that KCl-induced nonreceptor-mediated, carbachol- and SP-induced receptor-mediated contractions are significantly decreased by inflammation in the longitudinal ileum muscle. Increased synthesis of NO may be responsible for these decreases in contractile responses because they were restored significantly by in vivo L-NAME injection. Inhibition of NOS with L-NAME injection may afford a new therapeutic approach to the treatment of gastrointestinal stasis in septic patients. J Pediatr Surg 37:901-905.     

Single umbilical artery and the VATER-animal model

Background/Purpose: Vascular disruption is recognized as a cause of congenital malformations. The authors analyzed the significance of single umbilical artery (SUA) in the Adriamycin-animal model to find out if it was associated with organ malformations.Methods: Pregnant SD rats were injected with Adriamycin intraperitoneally at a dose of 2 mg/kg on days 6 through 9 of gestation. Serial transverse sections of full-term fetuses were analyzed by light microscopy. Embryos also were removed on different gestational days during organogenesis, and serial transverse histologic sections were examined and compared with suitable controls.Results: In experimental embryos (n = 47), presence of a SUA resulted from either persistence of the primitive umbilical arteries that joined each other ventral to the hind gut to give rise to one umbilical artery or from secondary atrophy of one of the definitive umbilical arteries. Malformations such as intestinal atresia were associated with anomalous fusion between the dorsal aorta and the persistent primitive umbilical arteries.Conclusions: SUA is a prominent feature of the Adriamycin-animal model. No obvious association was found between malformations and SUA that resulted from atrophy of one of the definitive umbilical arteries; however, it was associated with anomalies such as intestinal atresia when it resulted from persistence of the primitive umbilical arteries.     

Enteric duplications presenting as antenatally detected abdominal cysts: is delayed resection appropriate?

Purpose: The aim of this study was to evaluate delayed elective resection of antenatally detected enteric duplication cysts.Methods: A retrospective casenote study of intraabdominal cysts detected antenatally between January 1991 and January 2002 found 37 fetuses with cysts. Twelve were enteric duplications. Two were duodenal, 1 was an 85-cm tubular jejunoileal duplication, and 9 were ileocecal. Asymptomatic cysts were followed with serial ultrasound scars and resected electively over 14 months.Results: Three neonates had small bowel obstruction demanding laparotomy: 1 of the 2 infants with duodenal duplication cysts, 1 infant with an ileocecal duplication, and the infant with the tubular duplication. One with an ileocecal duplication became symptomatic at 2 months and underwent a laparotomy. Seven had their duplications resected electively between 6 weeks and 14 months, and the other is still being followed. Four of the 7 asymptomatic duplications electively resected contained gastric mucosa.Conclusions: Intraabdominal enteric duplication cysts are increasingly likely to be detected antenatally. The majority are likely to remain asymptomatic for several months at least, after which a resection can be planned. The prevalence of gastric mucosa suggests that they should not be left indefinitely. Laparoscopically assisted resection of ileocecal duplications is safe and effective.     

Notochord anomalies in the adriamycin rat model: A morphologic and molecular basis for the VACTERL association

Background/Purpose: The Adriamycin rat model (ARM) is a reliable model of the VACTERL association. The notochord is structurally abnormal in the region of the foregut, midgut, and hindgut in the ARM. The authors hypothesised that notochord anomalies allow ectopic expression of molecular signals in the developing embryo and thus lead to VACTERL malformations. This study was designed to investigate this hypothesis. Methods: Adriamycin (1.75 mg/kg) was administered intraperitoneally to pregnant rats on days 7, 8, and 9 of gestation. Control animals were given saline. Embryos were recovered on gestational days 10.5 to 14 at [frac12]-day intervals and at full term. The first group of embryos were embedded in resin, and sagittal sections stained with Toluidine blue were studied for morphologic abnormalities. The second group of embryos were examined using in situ hybridization for the expression of Sonic Hedgehog (Shh), a patterning gene implicated in the etiology of the VACTERL association. Results: Twenty-seven of the 28 (96.4%) full-term embryos showed VACTERL anomalies. Forty-five of the 50 (90%) experimental embryos (gestational days 10.5 to 14) showed notochord abnormalities. Abnormal ventral branches from the notochord toward the gut were a commonly observed abnormality. These were seen to impinge on the developing foregut, midgut, dorsal aorta, and kidney. In situ hybridization for Shh showed that these branches from the notochord expressed Shh in 66.6% of experimental embryos. This abnormal Shh expression was not seen in the control embryos. Conclusions: Adriamycin diffusely induces altered notochord morphology in the rat embryo. The abnormal notochord morphology may allow ectopic expression of Sonic Hedgehog, and, thus, contribute to the malformations found in the VACTERL association. J Pediatr Surg 38:469-473.     

Quality of life after gastric transposition for oesophageal atresia

Background/Purpose: A small proportion of infants born with oesophageal atresia in which the gap between the 2 ends of the oesophagus is too great for an end-to-end anastomosis will require oesophageal replacement. Since 1981 the author's procedure of choice for oesophageal replacement has been gastric transposition. The long-term functional outcome appears to be satisfactory, but the quality of life of these patients has not been investigated formally. This report assesses the health-related quality of life (QOL) of 2 groups of patients born with oesophageal atresia who have undergone gastric transposition. Methods: The study group comprised 28 patients aged 2 to 22 years who resided in England. Group 1 (n = 13), comprised patients who had undergone cervical oesophagostomy and gastrostomy without attempt at oesophageal anastomosis; group 2 (n = 15), comprised patients who had undergone previous attempts at reconstruction or replacement. QOL was assessed using modified versions of the Gastrointestinal Quality Of Life Index (GIQLI). Results: QOL scores based on patients' responses showed no significant differences between the groups (124 v 119). However, the disease-specific symptom scores showed that patients in group 1 experienced fewer symptoms compared with those in group 2. Additionally, based on parental responses, patients in group 1 had higher QOL scores than those in group 2. QOL scores for patients aged 2 to 4 years (n = 5) did not differ between the groups (81 v 92, not significant). Conclusions: The quality of life for patients with oesophageal atresia undergoing gastric transposition was generally unimpaired by any side effects of gastric transposition. Patients undergoing gastric transposition as a primary procedure experienced fewer disease-specific symptoms in the medium term compared with patients who had undergone previous unsuccessful attempts at reconstruction or replacement of their oesophagus. J Pediatr Surg 38:53-57.     

Outcomes in esophageal atresia and tracheoesophageal fistula

Background/Purpose: The purpose of this analysis was to investigate outcomes in newborns with esophageal atresia (EA) or tracheoesophageal fistula (TEF) with respect to prognostic classifications and complications.Methods: Charts of all 144 infants with EA/TEF treated at British Columbia Children’s Hospital (BCCH) from 1984 to 2000 were reviewed. Patient demographics, frequency of associated anomalies, and details of management and outcomes were examined.Results: Applying the Waterston prognostic classification to our patient population, survival rate was 100% for class A, 100% for class B, and 80% for class C. The Montreal classification survival rate was 92% for class I and 71% for class II (P = .08). Using the Spitz classification, survival rate was 99% for type I, 84% for type II, and 43% for type III (P < .05). The Bremen classification survival rate was 95% “without complications” and 71% “with complications.” Complications included stricture (52%), gastroesophageal reflux (31%), anastomotic leakage (8%), recurrent fistula (8%), and pneumonia (6%). Seventeen patients underwent fundoplication for gastroesophageal reflux, 16 pre-1992 and one post-1992.Conclusions: Comparing the major prognostic classifications, the Spitz classification scheme was found to be most applicable. In our institution, the trend in management of gastroesophageal reflux after repair of EA/TEF has moved away from fundoplication toward medical management.     

Deficient motor innervation of the sphincter mechanism in fetal rats with anorectal malformation: a quantitative study by fluorogold retrograde tracing

Background/purpose: Deficiency of motoneuron innervation to the sphincter mechanism has been described in patients with anorectal malformation. Whether this event is primary or secondary remains unclear.Methods: The authors quantified the motoneuron innervation of the sphincter mechanism by Fluorogold (FG) retrograde tracing experiment in fetal rats with anorectal malformation. Anorectal malformation was induced in rat fetuses by ethylenethiourea (ETU). Serial longitudinal sections encompassing the whole width of lumbosacral spinal cord were examined. The number of FG-labelled motoneurons were scored and compared between male fetuses with or without malformation in the ETU-fed group and normal controls.Results: The number of FG-labelled motoneurons in the fetuses without defect, with imperforate anus (IA), with neural tube anomalies (NTA), with combined IA and NTA, and normal controls were determined to be (mean ± SEM) 109.13 ± 37.88, 55.05 ± 25.85, 48.20 ± 30.34, 54.43 ± 28.55, and 135.22 ± 28.78, respectively. FG-labelled motoneurons in the fetuses with IA, NTA, and combined IA and NTA are significantly fewer than that in fetuses without defects (P < .05) and in normal controls (P < .005).Conclusions: These findings suggest that defective motoneuron innervation to the sphincter mechanism is a primary anomaly that coexists with the alimentary tract anomaly in anorectal malformation during fetal development. The intrinsic neural deficiency is an important factor likely to contribute to poor postoperative anorectal function despite surgical correction of anorectal malformation.     

Pulmonary effects of in utero tracheal occlusion are dependent on gestational age in a rabbit model of diaphragmatic hernia

Purpose: The authors investigated the effect of gestational age on lung development and maturation after in utero tracheal occlusion (TO) in a rabbit model of congenital diaphragmatic hernia (CDH). Methods: In 46 fetal rabbits, CDH was created at 23 days' gestational age (GA; term, 31 days), corresponding to the pseudoglandular phase of lung development. A second intervention was performed at either 26, 27, or 28 days on 6 fetuses in each GA group. At that time, either TO (CDH + TO), or a sham operation (CDH + sham) was performed. Nonoperated littermates served as internal normal controls (CTR). All fetuses were delivered by cesarean section at 30 days GA to assess lung response by lung-to-body-weight ratio, pulmonary morphometry, and the density of type II pneumocytes. Results: After TO, the lungs were significantly larger than in CDH animals; their weight was proportional to the duration of TO. Pulmonary morphometry in TO fetuses was comparable with that of controls. The density of type II cells was inversely related to the gestational age at which TO was performed, with normal values with TO at GA at 28 days. Conclusion: Timing of TO is critical to subsequent pulmonary development: early in gestation TO leads to pulmonary overgrowth and type II pneumocyte depletion, whereas normal values are obtained when TO is delayed till 28 of 32 days.     

Optimal timing of prenatal treatment of obstructive uropathy in the fetal lamb

Purpose: It was still unclear how urinary tract obstruction alters normal nephrogenesis and leads to renal dysplasia. The authors created an obstructive uropathy model in fetal lambs and reviewed the pathology of the obstructed kidney to determine the optimal timing for decompression of the obstruction.Methods: Obstructive uropathy was created in fetal lambs at 60 days’ gestation by ligating the urethra and urachus. They were delivered 20 to 31 days later by cesarian section. The kidneys were processed for histologic examination.Results: Thirty-four 60-day lambs were operated on. Dysplastic changes were noted in 25 fetuses, and 24 fetuses had cysts in the nephrogenic zone. The cystic components in multicystic dysplastic kidneys (MCDK) are mainly in the proximal tubules.Conclusions: In utero urinary tract obstruction causes reduction of numbers of functioning nephrons and produces cysts in the nephrogenic zone and in the deeper cortex. These cysts and dilated proximal tubules suppress new nephron formation. Twenty days after obstruction, there were early features of dysplasia, but the nephrogenic zones still were present. Early shunting may salvage renal function.     

Meconium dependence of bowel damage in gastroschisis

Background/Purpose: Increasing evidence of physiologic in utero defecation supports the hypothesis that bowel damage in gastroschisis may be meconium dependent. In this study, the author investigated the role of meconium on parameters of bowel damage in a fetal rat model of gastroschisis. Methods: Pregnant rats underwent laparotomy at 18 1/2 days gestational age (GA). There were 4 experimental groups of 11 fetuses each; the G_M group consisted of fetuses with isolated gastroschisis and was considered to have moderate meconium contamination of the amniotic fluid (MCAF); the G_L group consisted of fetuses with gastroschisis and anal ligation, performed to prevent MCAF; the G_H group consisted of fetuses with gastroschisis and colon perforation, performed to increase MCAF; and the Sham group consisted of sham operated controls. All fetuses were harvested by cesarean section at 21 1/2 days GA, and the fetal intestine was assessed for peel, intestinal length, intestinal weight per unit length, and histologic appearance. Results: The authors achieved the following fetal survival rates: G_M group, 91% (10 of 11); G_L group, 78% (7 of 9, the ligation was not successful in 2 fetuses); G_H group, 82% (9 of 11). Sham group, 100% (11 of 11). Intestinal length was decreased in fetuses with gastroschisis, and this reduction was related directly to the grade of MCAF (Sham, 18.4 [plusmn] 0.6; G_L, 11.5 [plusmn] 0.5; G_M, 10.2 [plusmn] 0.6; G_H, 9.1 [plusmn] 0.6 cm; P [lt ] .01). In contrast, intestinal weight per unit length increased in fetuses with gastroschisis, and this increase was related directly to the grade of MCAF (Sham, 7.8 [plusmn] 0.5; G_L, 9.4 [plusmn] 0.5; G_M, 11.3 [plusmn] 0.5; G_H, 16.9 [plusmn] 0.7 mg/cm; P [lt ] .01). In comparison with the G_M group, the degree of peel coverage and bowel adherence were increased markedly in the G_H group, whereas the fetuses of the G_L group had neither peel nor bowel adherence. Conclusions: All bowel damage parameters were affected by MCAF supporting the hypothesis that bowel damage in gastroschisis is at least partially dependent on meconium exposure. Further research is required to clarify other factors that contribute to bowel damage and to identify risk factors that may allow prenatal identification of severely affected fetuses.     

Effects of amnio-allantoic fluid exchange on bowel contractility in chick embryos with gastroschisis

Background/Purpose: Intestinal damage in patients with gastroschisis is characterized by bowel wall thickening, intestinal dilatation, mesenteric shortening, and a fibrous peel. The prevention of intestinal damage in gastroschisis by amnio-allantoic fluid (AAF) exchange has been reported using histologic and macroscopic evaluation of intestines, but the effects of this treatment on bowel contractility have not been investigated. The current study was performed to determine the effect of AAF exchange on the intestinal contractility in chick embryos with gastroschisis. Methods: Thirteen-day-old fertilized chick eggs were used. Gastroschisis was created through amnio-allantoic cavity. There were 3 study groups: control group, gastroschisis-only group, and gastroschisis-plus-exchange group. The bowels were evaluated by an in vitro muscle strip technique, and the response was expressed as a percentage of the maximum acetylcholine evoked contraction (E_max) in each tissue obtained. Additionally, parasympathetic ganglion cells per 10 plexus at the intestinal wall were counted. Differences between groups were analyzed by analysis of variance (ANOVA) followed by Tukey-Kramer. Probabilities of less than 5% were considered significant. Results: The intestines were thickened and covered by fibrous peel in the gastroschisis-only group when compared with the control group and the gastroschisis exchange group morphologically. There was a statistically significant decrease in contractility in the gastroschisis-only group compared with the control group (P [lt ] .05). It exerted 42.03 [plusmn] 46.73% contraction of control group's E_max. This decrease in contractility was significantly reversed in the exchange group (P [lt ] .05; E_max value of gastroschisis plus exchange group was 71.45 [plusmn] 23.54% of control group's E_max). Although the number of ganglia per 10 plexus was 76.7 [plusmn] 4.3 in the control group, it was measured 28% less in the gastroschisis-only group (P [lt ] .05). There was no significant difference between the ganglion numbers of control and exchange groups. Conclusions: Prenatal AAF exchange treatment prevents decreased bowel contractility in gastroschisis. Gastroschisis does not affect intestinal ganglia morphology, but the number of ganglion cells decreases. AAF exchange prevents these functional and morphologic adverse effects of disease. By these findings the expectancy of a better clinical result in gastroschisis with intrauterine pretreatment by amniotic fluid exchange increases.     

Positive intrapulmonary oncotic pressure enhances short-term lung growth acceleration after fetal tracheal occlusion

Purpose: This study was aimed at determining whether positive oncotic pressure induced in the fetal lung liquid could safely maximize accelerated lung growth after tracheal occlusion. Methods: Fetal lambs (n = 21) were divided into 4 groups: group I (n = 5) consisted of sham-operated controls; group II (n = 5) underwent simple tracheal occlusion (TO); group III (n = 5) received TO and 60 mL of saline injected into the trachea; and group IV (n = 6) underwent TO and intratracheal infusion of 60 mL of iso-osmotic, 6% Dextran 70. All fetuses were delivered near term, at a mean of 15.9 [plusmn] 1 days postoperatively. Their lungs were studied by standard morphometric techniques, and the basic chemical profile of the lung liquid was analyzed. Statistical comparisons were by 1-way analysis of variance (ANOVA) and post-hoc analyses by the Bonferroni correction for multiple comparisons, with P values less than .05 considered significant. Results: The lung volume-to-body-weight ratio (LV:BW) was significantly different among groups. Pairwise comparisons of LV:BW showed that it was higher in group IV than in all other groups, but there was no difference between groups II and III. Airspace fraction was not significantly different among groups, and histologic appearance was normal in all lung samples. There were no differences in lung liquid osmolarity, pH level, and electrolyte concentrations. Conclusion: Positive intrapulmonary oncotic pressure by an isosmotic agent boosts short-term lung growth acceleration after fetal tracheal occlusion with no evidence of cell damage. J Pediatr Surg 37:1007-1010.