AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Airway-by-Airway Imaging of Particles Deposited in Animal Lungs
CHRISTOPHER WALLIS, DongYoub Lee, Annalisa Smullin, Anthony Wexler, University of California Davis
Abstract Number: 369 Working Group: Health Related Aerosols
Abstract Laboratory animals are widely used as models for exploring both adverse and beneficial health effects caused by inhalation of suspended particles. Administering therapeutic drugs by inhalation offers advantages such as avoidance of first pass metabolism, faster absorption, low cost, and patient convenience. Knowledge of where particles have deposited is an important factor in understanding the effects of this type of administration. Similarly, such knowledge also aids studies of harmful effects from exposure to suspended particles through occupational exposure, air pollution, or smoke. Mapping deposition throughout the airways of laboratory animals is crucial since the location often determines subsequent transport and the health effects elicited. There are few methods for identifying the exact pattern of deposition once the drug or particle enters the airways.
Here we present a newly developed method for simultaneously imaging airways and deposited particles in three dimensions with high resolution. Inhalation exposure to fluorescent particles is performed and the lungs are then inflated and flash frozen. Silicone casting material mixed with fluorescent dye of a different color is injected into the frozen lung to support and color the lumen. The lung is then embedded in ice and mounted in an Imaging Cryomicrotome. This instrument is used to serially section the sample while capturing fluorescent images of the block face at each slice. Optical excitation and emission bands are chosen to separately image the deposited particles and fill material. Slicing unfixed lung tissue presents a challenge, even when frozen. A fine water mist is employed intermittently throughout the slicing process to further support the tissue. We present our preliminary results, including three dimensional reconstruction of both the conducting airways and deposited particles, as well as numerical analysis of deposition in individual airway segments.