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 pulm onary fibrosis in the bronchiolar-alveolar regions of humans and exper imental animals. The fibrogenic lesions were described previously by m orphometry in a rodent model of asbestos-induced pulmonary fibrosis in our laboratory. Our prior studies also showed that incorporation of t ritiated thymidine (H-3-TdR) into nuclei of epithelial and interstitia l cells of bronchiolar-alveolar regions correlates with this histopath ologic response. The study presented here describes the early prolifer ative response in the bronchiolar-alveolar regions in mice after a bri ef exposure to chrysotile asbestos. Mice exposed to asbestos had signi ficantly increased incorporation of bromodeoxyuridine (BrdU) in inters titial and epithelial cells of first alveolar duct bifurcations and te rminal 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.