Apoptosis in various organs of preterm infants: Histopathologic study of lung, kidney, liver, and brain of ventilated infants

Apoptosis, the well-characterized form of active programmed cell death, is a physiologic phenomenon in embryonal and fetal life in developing organs. Severe hypoxia, which occurs in most preterm infants, also leads to cell de ath, which may be necrotic or apoptotic. The aim of our study was to examin e the incidence of apoptosis in various organs (such as lung, kidney, and b rain) of preterm infants who suffered from clinically proven respiratory di stress causing infantile respiratory distress syndrome (IRDS), cardiac fail ure, and periventricular leukomalacia (PVL). Twenty-four autopsy cases were studied histologically to detect the apoptotic ratio, which was performed on the basis of hematoxylin and eosin staining and validated by terminal de oxynucleotidyl transferase-mediated nick end-labeling (TUNEL) reaction. Ele vated apoptotic ratio was found in stages II, III, and IV of bronchopulmona ry dysplasia (BPD) among alveolar and bronchiolar cells. The apoptotic acti vity was very low in stage I of BPD. High apoptotic ratio was detected in h ypoxic injuries of the central nervous system (CNS) of preterm infants. Fea tures of apoptosis were present in proximal and excreting tubules of the ki dney. Significant elevation of apoptotic activity may play a role in the de velopment of BPD, ischemic brain lesions, and renal failure.