Objectives: The novel micro-optical coherence tomography (µOCT) imaging technique provides cross-sectional images of the airway epithelium at a resolution of ∼1μm, sufficient to directly visualize and quantify microanatomic parameters (airway surface liquid (ASL) & periciliary liquid (PCL) depth, ciliary beat frequency (CBF), and mucociliary transport rate). We would like to demonstrate μOCT applied to sinonasal airway epithelium, both in cultures and tissue ex vivo, providing a new tool to interrogate the functional microanatomy of sinonasal epithelia.
Methods: Measurements of functional microanatomic parameters in primary human sinonasal epithelial (HSNE) cells and ex vivo rabbit sinus tissue were performed using μOCT, a high-speed and high-resolution microscopic reflectance imaging modality. HSNE cell cultures were subjected to hypoxic environment for 12hrs to induce acquired CFTR dysfunction. Rabbit’s middle meatus was blocked to create acute and chronic sinusitis. ASL, PCL, and CBF were evaluated.
Results: Hypoxia diminished all markers of mucociliary clearance (MCC) on µOCT, including ASL (5.0+/-0.4 vs 9.0+/-0.9 µm; p<0.01), PCL (2.5+/-0.1 vs 4.8+/-0.3 µm; p<0.01), and CBF (8.7+/-0.3 vs 10.2+/-0.3 Hz; p<0.01). Sinus epithelia from both acute and chronic sinusitis rabbits demonstrated significantly lower PCL depth (Acute=3.45+/-0.1 µm, Chronic=3.27+/-0.06 µm) compared to controls (control=6.74+/-0.4 µm) (p<0.0001). CBF was significantly diminished in chronic sinusitis compared to controls (control=7.4+/-0.34 vs Chronic=6.35+/-0.15 Hz, p=0.007).
Conclusions: The high resolution of μOCT allows many functional parameters to be measured simultaneously and directly, enabling comprehensive study of the MCC apparatus. This imaging method represents a technological leap forward in the assessment of acquired defects in the MCC apparatus.
