MC3T3-E1-conditioned medium-induced mineralization by clonal rat dental pulp cells

• Published in: Matrix biology 2001-09, Vol.20 (5), p.347-355
• Main Authors: Ueno, Akemichi, Kitase, Yukiko, Moriyama, Keiji, Inoue, Hideo
• Format: Article
• Language: English
• Subjects: Alkaline Phosphatase - drug effects; Animals; Bone Morphogenetic Proteins - metabolism; Cell Line - cytology; Clone Cells; Coculture Techniques; Conditioned medium; Culture Media, Conditioned - metabolism; Culture Media, Conditioned - pharmacology; Dental Pulp - cytology; Dental Pulp - drug effects; Dental Pulp - metabolism; Dental Pulp Calcification - metabolism; Dental pulp cells; Extracellular Matrix Proteins - metabolism; MC3T3-E1 preosteoblasts; Mice; Mineralization; Osteoblasts - cytology; Osteoblasts - metabolism; Rats; Rats, Wistar; RNA, Messenger - drug effects; RNA, Messenger - metabolism; Transforming Growth Factor beta - metabolism
• ISSN: 0945-053X; 1569-1802
• DOI: 10.1016/S0945-053X(01)00141-X

Dental pulp is thought to participate in supplementary mineralization, such as reparative dentin and pulp stones, but no direct proof of this has been reported. To study this process at a molecular level, we investigated the matrix mineralization of dental pulp using a clonal cell line (RPC-C2A) derived from rat incisor dental pulp. Mineralized nodules in extracellular matrix were formed by RPC-C2A cells cultured in the presence of conditioned medium (CM) from confluent osteoblastic MC3T3-E1 cells. These nodules were stained by the von Kossa method and with alizarin red S and quantified by the measurement of acid-soluble calcium deposition. This CM was most effective when collected 3–6 days after confluency and added at 50% to the culture medium. The CM-treated RPC-C2A cells showed high alkaline phosphatase activity, a high mRNA level of osteocalcin and decreases in the mRNA levels of osteopontin and osteonectin, but undetectable levels of mRNA of dentin sialophosphoprotein by Northern blot analyses. A pan-specific anti-transforming growth factor (TGF)-β antibody and a soluble form of receptor for bone morphogenetic protein (BMP)-2/-4 did not neutralize the CM-induced mineralization. These results suggest that some soluble factor(s) other than TGF-β or BMP-2/-4 in the CM from MC3T3-E1 cells cause differentiation of RPC-C2A cells to osteoblast-like cells.