Long hypoplasia in CDH, effects of tracheal occlusion on type 2 cell mutual

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 11671767
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Pediatric surgery
• Research Institution: Tokyo University
• Principal Investigator: KITANO Yoshihiro University of Tokyo Faculty of Med Assista, 医学部・附属病院, 助手 (30261994)
• Co-Investigator(Kenkyū-buntansha): KOZUMA Shiro University of Tokyo Faculty of Med Associate Pr, 医学部・附属病院, 助教授 (10272569) ; KOHEI Hashizume University of Tokyo Faculty of Med Profess, 医学部・附属病院, 教授 (50180815)
• Project Period (FY): 1999 – 2000
• Keywords: congenital diaphragmatic hernia / fetal surgery / surfactant / tracheel occlusion

Research Abstract

To determine the timing when fetal lung development starts to be affected by the presence of congenital diaphragmatic hernia (CDH), 100 milligram of Nitrofen was administered to a time-dated pregnant rat to induce left sided CDH in the fetuses. The fetuses were harvested on 18, 19, 20, and 21.5 days gestation and the wet weight, dry weight, and histology of the fetal lungs were compared between the fetuses with left-sided CDH and the controls without CDH.There was no difference between the two groups on day 18 and 19 in either wet or dry lung weight. On day 20, only lung wet weight was significantly decreased in the fetuses with CDH.On day 21.5, both wet and dry lung weights were significantly decreased in the CDH fetuses. Although the diaphragmatic defect in the rat model of CDH occurs when the fetal lung is in the early pseudoglandular stage, it was not until the late canalicular stage when lung weight and histology was first affected by the presence of CDH.
To determine the effects o f fetal tracheal occlusion (TO) on type 2 cell proliferation and maturation, TO was performed on 4-5 randomly chosen fetuses of time-dated pregnant Sprague-Dawley rats on fetal day 19. We recently reported significant lung growth in this model [J Pediatr Surg 33(12) : 1741-1744,1998]. Fetuses were sacrificed on 21.5 days gestation for comparison of type 2 cells and surfactant proteins using Western blotting, immunohistochemistry, and transmission electron microscopy. There were no significant differences in SP-A and SP-B levels by Western-blotting of lung homogenates from TO and Control lungs. This was confirmed by immunohistochemistry using antibodies for SP-A, B, and NPro-SP-C, which showed similar staining intensity of type 2 cells in both the TO and Control lungs. Further electron microscopic studies revealed similar numbers of intracellular mature lamellar bodies and glycogen lakes per type 2 cell. The number of type 2 cells per alveolus was smaller in the TO group. We conclude that TO had minimal effects on proliferation or differentiation of type 2 cells in fetal rats. Developmental stage at and duration of TO are likely to be crucial factors in balancing the effects of TO on lung growth versus maturation.