Elastin and fibrillin mRNA and protein levels in the ontogeny of normal human aorta.

Elastin associated microfibrils (EAMF) are ubiquitous connective tissue structures that are believed to provide tensile strength and flexibility to numerous tissues. In this study the ontogeny of EAMF in normal human aorta was examined using immunohistochemical analysis of fibrillin, an EAMF component, and mRNA levels of fibrillin and elastin. Specimens of infra-renal aorta from ages 11 months to 44 years were obtained following organ procurement. Decreasing amounts, as judged by computer digitized image analysis, of immunoreactive fibrillin when compared to elastin auto-fluorescence were observed in aortic sections with increasing age. Elastase treatment would un-mask the anti-fibrillin reactive epitope reinforcing the suggestion that EAMF act as a "scaffold" for elastin deposition. Northern and dot blot hybridizations demonstrated a decrease in relative fibrillin message levels with increasing age. The abundance of fibrillin in relation to elastin may suggest a role for EAMF independent of their association with elastin.