Elevated Oxygen Fraction Reduces Cilial Abundance in Explanted Human Bronchial Tissue

Abstract

The effect of hyperoxia on ciliary abundance in cultured explants of adult human bronchus was investigated. Bronchus samples were removed during surgery from patients receiving pneumonectomy or lobectomy for malignancy. Part or all of each of these samples was used for measurement of cilial abundance by scanning electron microscopy (SEM); in many cases the remainder was subdivided and cultured at 37°C in DMEM medium, maintaining an air interface at the ciliated surface of each segment. Cultured segments were exposed to normoxia or hyperoxia (95% O₂), and a segment was removed every other day for quantification of cilial abundance by SEM. There was a significant inverse relationship between smoking history and abundance (p = .017; ANOVA); mean values for nonsmokers, ex-smokers, and smokers were 98.2% (n = 6), 97.0% (n = 17), and 84.02% (n = 9), respectively. There was some loss of cilia on explant segments cultured under normoxia, but the rate of loss from segments cultured under hyperoxia was significantly greater (W test, p = .00011); rate constants (means ± SE) for cilial loss of 0.0208 ± 0.0044 day⁻¹ and 0.0880 ± 0.0179 day⁻¹ were found for explant segments exposed to 21 and 95% O₂, respectively (n = 20).

KEYWORDS:

• bronchi
• cilia
• electron microscopy
• human
• hyperoxia
• respiratory mucosa