Hyperoncotic enhancement of fetal pulmonary growth after tracheal occlusion: an alveolar and capillary morphometric analysis

Albumin as an adjunct to tracheal occlusion in fetal rats with congenital diaphragmatic hernia: a placebo-controlled study

OBJECTIVE

We sought to investigate effects of intratracheal albumin injection prior to tracheal occlusion (TO) on lung proliferation in fetal rats with nitrofen-induced congenital diaphragmatic hernia.

STUDY DESIGN

On embryonic day 19, nitrofen-exposed fetuses underwent TO, TO and 50 microL of either intratracheal albumin 20% or saline, or remained untouched. Main outcome at embryonic day 21.5 was expression of the proliferation marker Ki-67. Secondary outcomes were lung-to-bodyweight ratio (LBWR), tropoelastin expression, density and spatial distribution of elastin, pulmonary/alveolar morphometry, and fetal survival.

RESULTS

TO increased Ki-67 messenger RNA and LBWR. Albumin further increased LBWR and density of Ki-67-positive cells but also fetal mortality. TO with or without adjuncts induced elastin deposits at the tips of arising secondary crests, increased air space size, and decreased septal thickness.

CONCLUSION

TO had effects on lung proliferation and advanced the morphologic appearance. Addition of albumin increased density of proliferating cells and LBWR, yet at the expense of additional fetal loss.

Congenital diaphragmatic hernia: a modern day approach

Centralization of all complicated congenital diaphragmatic hernias (CDH) was organized in Germany from 1998, collecting 325 consecutive patients with striking increasing survival rates. This series report 244 patients from 2002 to 2007. Today, large defects are detected early in pregnancy by ultrasound and magnetic resonance imaging (MRI). In extracorporeal membrane oxygenation (ECMO) patients, prenatal lung head ratio (LHR) was 1.2 (median) at the 34th week of gestation or less than 25 ml lung tissue in MRI. This means that all patients below LHR of 1.4 should be transferred prenatally in a tertiary center. High risk group for survival was defined as LHR below 0.9, ie, 10 ml in MRI planimetry. Inborn patients show better results than outborns. In algorithm therapy, gentle ventilation plays an important role in preventing damage to the lung tissue and avoiding long term ventilation. When PaCO(2) was more than 75 mmHg, ventilation was changed to high frequency oscillatory ventilation (HFOV). Indication for ECMO was seen in preductal PaO(2) less than 50 mmHg over 2-4 h or less than 40 mmHg over 2 h. ECMO related risks included intracerebral bleeding (9%), intrapulmonary bleeding (14%), and convulsions (16%). Surgically, a longitudinal midline incision for exposure of the defect, the duodenal kinking, and probably for abdominal patching was perfect. A cone formed goretex patch provided more abdominal space and reduced abundant intrathoracical cavity. No drain was used. Postoperative complications were described. Overall survival in 244 consecutive patients was 86.5% for all patients born alive. All those who needed ECMO survived in 71%, underlining ECMO as a treatment of last choice. Follow-up for quality of life after CDH is described.

Stem cells in amniotic fluid as new tools to study human genetic diseases

In future, the characterization and isolation of different human stem cells will allow the detailed molecular investigation of cell differentiation processes and the establishment of new therapeutic concepts for a wide variety of diseases. Since the first successful isolation and cultivation of human embryonic stem cells about 10 years ago, their usage for research and therapy has been constrained by complex ethical consideration as well as by the risk of malignant development of undifferentiated embryonic stem cells after transplantation into the patient's body. Adult stem cells are ethically acceptable and harbor a low risk of tumor development. However, their differentiation potential and their proliferative capacity are limited. About 4 years ago, the discovery of amniotic fluid stem cells, expressing Oct-4, a specific marker of pluripotent stem cells, and harboring a high proliferative capacity and multilineage differentiation potential, initiated a new and promising stem cell research field. In between, amniotic fluid stem cells have been demonstrated to harbor the potential to differentiate into cells of all three embryonic germlayers. These stem cells do not form tumors in vivo and do not raise the ethical concerns associated with human embryonic stem cells. Further investigations will reveal whether amniotic fluid stem cells really represent an intermediate cell type with advantages over both, adult stem cells and embryonic stem cells. The approach to generate clonal amniotic fluid stem cell lines as new tools to investigate molecular and cell biological consequences of human natural occurring disease causing mutations is discussed.

Vitamin A deficiency (VAD), teratogenic, and surgical models of congenital diaphragmatic hernia (CDH)

Congenital diaphragmatic hernia (CDH) is a congenital malformation that occurs with a frequency of 0.08 to 0.45 per 1,000 births. Children with CDH are born with the abdominal contents herniated through the diaphragm and exhibit an associated pulmonary hypoplasia which is frequently accompanied by severe morbidity and mortality. Although the etiology of CDH is largely unknown, considerable progress has been made in understanding its molecular mechanisms through the usage of genetic, teratogenic, and surgical models. The following review focuses on the teratogenic and surgical models of CDH and the possible molecular mechanisms of nitrofen (a diphenyl ether, formerly used as an herbicide) in both induction of CDH and pulmonary hypoplasia. In addition, the mechanisms of other compounds including several anti-inflammatory agents that have been linked to CDH will be discussed. Furthermore, this review will also explore the importance of vitamin A in lung and diaphragm development and the possible mechanisms of teratogen interference in vitamin A homeostasis. Continued exploration of these models will bring forth a clearer understanding of CDH and its molecular underpinnings, which will ultimately facilitate development of therapeutic strategies.

Prenatal intervention for congenital diaphragmatic hernia

Advances in prenatal ultrasound have revealed the poor natural history of fetal congenital diaphragmatic hernia (CDH) and its hidden mortality during gestation and immediately after birth. Attempts to improve this poor outcome led to the development of prenatal surgical intervention for severe CDH by Harrison and his colleagues at the University of California San Francisco. Prenatal surgical intervention for CDH has seen four phases: open fetal surgical repair, open surgical tracheal occlusion, endoscopic external tracheal occlusion, and endoscopic endoluminal tracheal occlusion. After extensive work in the laboratory, prenatal intervention has been applied in humans since 1984. With the most recent techniques, maternal risk is significantly reduced as is the incidence of preterm labor. In the meantime, the survival rate of fetuses with CDH without fetal intervention has improved mainly due to the minimization of iatrogenic lung injury by gentle ventilation, first described in 1985. However, the morbidity of the survivors with severe CDH remains high. Prenatal intervention for CDH will be justified if improvement in survival or morbidity can be demonstrated when compared to planned delivery and postnatal management with gentle ventilation strategy.