Histological and immunohistochemical study of the bronchial stump with flap coverage in an animal model

The purpose of our study was to evaluate the healing process of the bronchial stump after pneumonectomy reinforced with different pedicled flaps in an animal model. The specimens were analyzed by means of histology and immunohistochemistry.

We have considered 45 New Zealand White male rabbits that underwent a left pneumonectomy under general anesthesia. Nine animals had no bronchial coverage and represented the controls. The other 36 rabbits were divided into three groups of 12 and had bronchial coverage with either diaphragmatic, intercostal or pericardial flaps. The histological examinations were performed on the animals sacrificed 7, 14 and 30 days after surgery. Immunohistochemical analyses were done on the specimens on postoperative day 7 and 14. On postoperative day 7, the specimens were examined for expression of proliferating cell nuclear antibody (PCNA) expression. On postoperative day 14, neoangiogenesis was measured by CD31 expression. The measurements of antibody expression were done with a computer-assisted morphometric count and analyzed with the t test.

On postoperative day 14, standard histology showed more evident neoangiogenesis in the bronchial stump specimens covered with intercostal and diaphragmatic flaps compared to pericardial flaps and controls. The immunohistochemical evaluation of PCNA by morphometric computer-assisted analysis did not show any statistically significant differences among the groups. The CD31 morphometric count revealed a higher and statistically significant antibody expression in muscular flaps compared to pericardial flaps and controls.

Our study showed that bronchial coverage with a pedicled muscular flaps promotes the production of new vessels and gives the possibilities to optimize the healing process of a bronchial stump after pneumonectomy.