Interactions of elastin and microfibrils in elastogenesis of human pulmonary fibroblasts in culture

The interaction of elastin and microfibrils in elastogenesis in vitro was investigated with electron microscopy and immunohistochemistry. Fetal human pulmonary fibroblasts were cultured with or without beta-aminopropionitrile (BAPN). One week after seeding, the extracellular microfibrils were loosely arranged without elastin deposition. Two and six week culture in controls, mature elastic fibers and microfibril bundles were formed. In cultures with BAPN, the microfibrils were loosely arranged, and a few microfibril bundles and no amorphous components were formed. Immunoelectron microscopy for elastin showed the reaction at the outer zones of amorphous components in controls, though the loosely-arranged microfibrils reacted diffusely in cultures with BAPN. Six week culture with BAPN, aggregated masses of elastin, which were dissociated from microfibrils, were found. In conclusion, deposition and maturation of elastin on microfibrils are necessary to form the microfibril bundles in normal elastogenesis, and vaguely outlined aggregated masses of elastin are formed under the inhibition of lysyl oxidase.