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Analysis of cartilage maturation using micromass cultures of primary chondrocytes
Author(s) -
Kameda Takashi,
Koike Chika,
Saitoh Kanako,
Kuroiwa Atsushi,
Iba Hideo
Publication year - 2000
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1046/j.1440-169x.2000.00508.x
Subject(s) - noggin , bone morphogenetic protein , microbiology and biotechnology , chondrogenesis , cartilage , bone morphogenetic protein 2 , chemistry , biology , gene , stem cell , anatomy , in vitro , biochemistry
A micromass culture (MM‐C) system of primary immature chondrocytes for functional analysis of soluble factors involved in the maturation step of cartilage was previously developed. Ectopically expressed BMP‐2 was shown to induce the expression of the Ihh and Noggin genes. Here it is demonstrated that, upon longer culture, secreted bone morphogenetic protein‐2 (BMP‐2) further promotes the maturation step as judged by the induction of type X collagen and BMP ‐6 expression, which are known to be detectable in the later phase of cartilage maturation. Induction of all of these genes by secreted BMP‐2 was not inhibited by ectopic expression of parathyroid hormone‐related peptide (PTHrP) induced by retrovirus vector infection, although the same virus vector showed strong inhibitory effects on the expression of type X collagen gene or alkaline phosphatase activity in mature chondrocytes. These results suggest that the maturation‐promoting activity exhibited by BMP‐2 is dominant over the suppressive effect of PTHrP in immature chondrocytes. When the BMP ‐6 gene was introduced into the same virus vector as that used for BMP‐2, it induced the same sets of genes ( Ihh, Noggin , type X collagen and endogenous BMP‐6) as BMP‐2 did. These results also suggest that BMP‐6 would autonomously maintain and/or promote a later stage of chondrocytic maturation.