Cloning of TPA-inducible early (TIE) genes by differential hybridization using TPA-nonresponsive variant of mouse 3T3-L1 cells

Use of isolated mature osteoblasts in abundance acts as desired-shaped bone regeneration in combination with a modified poly-DL-lactic-co-glycolic acid (PLGA)-collagen sponge

Controlled regeneration of bone or cartilage has recently begun to facilitate a host of novel clinical treatments. An osteoblast line, which we isolated is able to form new bone matrix in vivo within 2 days and exhibits a mature osteoblast phenotype both in vitro and in vivo. Using these cells, we show that cuboidal bones can be generated into a predesigned shaped-bone with high-density bone trabeculae when used in combination with a modified poly-DL-lactic-co-glycolic acid (PLGA)-collagen sponge. PLGA coated with collagen gel serves as a good scaffold for osteoblasts. These results indicate that mature osteoblasts, in combination with a scaffold such as PLGA-collagen sponge, show promise for use in a custom-shaped bone regeneration tool for both basic research into osteogenesis and for development of therapeutic applications.

Phorbol-ester-mediated expression of the collagen type I pro-alpha 2 gene in mouse 3T3-L1 cells and its absence in a phorbol 12-myristate 13-acetate-non-responsive variant

We have previously isolated a phorbol 12-myristate 13-acetate (PMA)-non-responsive variant line (VT-1) from mouse 3T3-L1 cells [Shimizu, Fujiki, Sugimura & Shimizu (1986) Cancer Res. 46, 4027-4031]. Differential hybridization of cDNAs obtained from PMA-treated 3T3-L1 and VT-1 cells resulted in the isolation of a number of unique cDNA clones, including one with a high degree of sequence similarity to the type I pro-alpha 2 collagen gene (COL1A2) [Amagai, Inokuchi, Nishikawa, Shimizu & Shimizu (1989) Somat. Cell Mol. Genet. 15, 153-158]. Here we examined the expression of type I collagen pro-alpha 2 [pro-alpha 2(I)] mRNA and production of type I collagen in these two cell lines. In quiescent cells, the pro-alpha 2(I) steady-state mRNA levels were four times greater in 3T3-L1 cells than in VT-1 cells. PMA addition caused the steady-state levels of pro-alpha 2(I) mRNA to be six times greater in 3T3-L1 cells than in VT-1 cells, with a maximum at 30-60 min. The pro-alpha 2(I) protein levels in the extracellular matrix or culture media of 3T3-L1 cells were substantially elevated by PMA treatment, but no significant increase was detected in VT-1 cells. The correlation of collagen expression with a PMA-mediated mitogenic response suggests a new role for collagen as an early component of mitogenic signal transduction.