INCORPORATION OF BROMODEOXYURIDINE AS A METHOD TO QUANTIFY CELL-PROLIFERATION IN BRONCHIOLAR-ALVEOLAR DUCT REGIONS OF ASBESTOS-EXPOSED MICE

Inhalation of asbestos fibers results in progressive interstitial pulmonary fibrosis in the bronchiolar-alveolar regions of humans and experimental animals. The fibrogenic lesions were described previously by morphometry in a rodent model of asbestos-induced pulmonary fibrosis in our laboratory. Our prior studies also showed that incorporation of tritiated thymidine (H-3-TdR) into nuclei of epithelial and interstitial cells of bronchiolar-alveolar regions correlates with this histopathologic response. The study presented here describes the early proliferative response in the bronchiolar-alveolar regions in mice after a brief exposure to chrysotile asbestos. Mice exposed to asbestos had significantly increased incorporation of bromodeoxyuridine (BrdU) in interstitial and epithelial cells of first alveolar duct bifurcations and terminal bronchioles at 48 h after exposure. The BrdU incorporation was similar at 24 h after exposure. This study confirms that BrdU provides information on asbestos-induced cell proliferation similar to that of H-3-TdR, but the technology is far safer and less time-consuming.