title: Sequential synthesis of cartilage and bone marker proteins during transdifferentiation of mouse Meckel's cartilage chondrocytes in vitro.
abstract: Meckel's cartilage cells cultured in vitro undergo phenotypic transformation toward osteogenic cells. We examined whether these cells synthesize type X collagen and bone morphogenetic protein-2 (BMP-2). We also examined the results of Alcian blue staining and the expression of type I and type II collagen, osteocalcin and chondroitin sulfate proteoglycan (CSPG) during this transdifferentiation. Meckel's chondrocytes, isolated from day-17 mouse embryos, were inoculated at 1 x 10(4)/penicylinder and cultured in alpha-MEM for periods up to 4 weeks. Alcian blue staining and immunostaining of type II collagen and CSPG confirmed that, after cell culture for 2 weeks, the cartilaginous phenotype was expressed most intensely. Later in culture, chondrocytes underwent modification through the synthesis of bone-type proteins; nodule-forming small round cells showed ALPase activity and were immunoreactive for type I collagen and osteocalcin. Immunoreactivity for type X collagen was detected in the small round cells at the top of the nodules prior to calcification of the matrix, as well as in large hypertrophic cells. BMP-2 was also expressed first in similar small round cells after 3 weeks in culture, and it subsequently extended along the extracellular matrix in the calcified nodules. These results indicate that small round cells that are differentiating toward osteocyte-like cells from Meckel's chondrocytes express type X collagen and BMP-2 sequentially.
authors.affiliation: Department of Oral Anatomy, School of Dentistry, Iwate Medical University, Morioka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ishizeki
authors.forename: Y
authors.initials: Y
authors.lastname: Hiraki
authors.forename: M
authors.initials: M
authors.lastname: Kubo
authors.forename: T
authors.initials: T
authors.lastname: Nawa
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002356:Cartilage / Q000196:embryology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism; D003094:Collagen / Q000378:metabolism*; D007150:Immunohistochemistry; D008334:Mandible / Q000196:embryology*; D051379:Mice; D008854:Microscopy, Electron; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis; D013997:Time Factors; D016212:Transforming Growth Factor beta
chemical_list: C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D011508:Chondroitin Sulfate Proteoglycans; D016212:Transforming Growth Factor beta; D015675:Osteocalcin; D003094:Collagen