H. Inoue et al., CHANGES IN PHENOTYPIC GENE-EXPRESSION IN RAT MANDIBULAR CONDYLAR CARTILAGE CELLS DURING LONG-TERM CULTURE, Journal of bone and mineral research, 10(11), 1995, pp. 1691-1697
Gene expression patterns have been investigated in prolonged cultures
of rat mandibular condylar cartilage (MCC) cells to examine the possib
ility of culture-induced phenotypic changes, MCC cells were isolated f
rom newborn rats and grown in the presence of 10% fetal bovine serum (
FBS) and basic fibroblast growth factor (bFGF). MCC cells were passage
d and cultured in the presence of 10% FBS and bFGF until confluent. Af
ter confluence, the medium was changed to that supplemented with 10% F
BS, ascorbate, and beta-glycerophosphate (day 1). Mineralization and g
ene expression of MCC cells have been investigated. Mineralization, vi
sualized by staining with Alizarin red, was observed to begin at day 1
3 in culture, and increased up to day 22 in culture, which was the len
gth of this study. Type II collagen and aggrecan mRNAs were highly exp
ressed at the start of culture (day 1-4) and decreased in a time-depen
dent manner. Type I collagen, alkaline phosphatase, and osteopontin mR
NAs expressed biphasic patterns that peaked at the start of culture an
d the beginning of mineralization (day 13-16), Osteonectin mRNA was ex
pressed throughout the culture period. Osteocalcin mRNA was expressed
before the beginning of mineralization peaking at day 7. These observa
tions suggest that the gene expression patterns of MCC cells can be ca
tegorized into two different periods in prolonged culture: maturation
(day 1-10) and mineralization (day 13-22). The cell culture system of
MCC represents a new model system in which the differentiation of embr
yonic MCC cells can be examined.