A MURINE OSTEOBLAST CELL-LINE (MC3T3) PRODUCES A SOLUBLE ELASTOGENIC COMPOUND

Elastofibromas are localized proliferations of mesenchymal cells that produce an exuberant amount of elastin-rich extracellular matrix. Rece ntly periosteal fibroblasts have been proposed to be the proliferating cell. The hypothesis has been tested that osteocytes or osteoblasts c ontribute to the formation of elastofibromas by secreting a compound(s ) that enhances elastin production. Media conditioned by murine calvar ial osteoblasts (MC3T3) increased tropoelastin synthesis in bovine lig amentum nuchae fibroblasts. Addition of MC3T3-conditioned medium to bo vine ligamentum nuchae fibroblast cultures produced a two-fold increas e in tropoelastin RNA. The maximal increase in tropoelastin RNA was be tween 16 and 24 h; tropoelastin mRNA had returned to control values by 40 h. A similar increase in tropoelastin protein production was detec ted. The soluble elastogenic compound was neither interleukin-l (IL-1) nor IL-6. These results support the hypothesis that an interaction be tween bone and perosteum may be involved in the formation of elastofib romas.