BMP-2 induction and TGF-beta 1 modulation of rat periosteal cell chondrogenesis.
Periosteum contains osteochondral progenitor cells that can differentiate into osteoblasts and chondrocytes during normal bone growth and fracture healing. TGF-beta 1 and BMP-2 have been implicated in the regulation of the chondrogenic differentiation of these cells, but their roles are not fully defined. This study was undertaken to investigate the chondrogenic effects of TGF-beta 1 and BMP-2 on rat periosteum-derived cells during in vitro chondrogenesis in a three-dimensional aggregate culture. RT-PCR analyses for gene expression of cartilage-specific matrix proteins revealed that treatment with BMP-2 alone and combined treatment with TGF-beta 1 and BMP-2 induced time-dependent mRNA expression of aggrecan core protein and type II collagen. At later times in culture, the aggregates treated with BMP-2 exhibited expression of type X collagen and osteocalcin mRNA, which are markers of chondrocyte hypertrophy. Aggregates incubated with both TGF-beta 1 and BMP-2 showed no such expression. Treatment with TGF-beta 1 alone did not lead to the expression of type II or X collagen mRNA, indicating that this factor itself did not independently induce chondrogenesis in rat periosteal cells. These data were consistent with histological and immunohistochemical results. After 14 days in culture, BMP-2-treated aggregates consisted of many hypertrophic chondrocytes within a metachromatic matrix, which was immunoreactive with anti-type II and type X collagen antibodies. In contrast, at 14 days, TGF-beta 1 + BMP-2-treated aggregates did not contain any morphologically identifiable hypertrophic chondrocytes and their abundant extracellular matrix was not immunoreactive to the anti-type X collagen antibody. Expression of BMPR-IA, TGF-beta RI, and TGF-beta RII receptors was detected at all times in each culture condition, indicating that the distinct responses of aggregates to BMP-2, TGF-beta 1 and TGF-beta 1 + BMP-2 were not due to overt differences in receptor expression. Collectively, our results suggest that BMP-2 induces neochondrogenesis of rat periosteum-derived cells, and that TGF-beta 1 modulates the terminal differentiation in BMP-2 induced chondrogenesis.
Skeletal Research Center and the Department of Biology, Case Western Reserve University, Cleveland, Ohio 44106, USA. hanada_keigo@kaken.co.jp
K
K
Hanada
L A
LA
Solchaga
A I
AI
Caplan
T M
TM
Hering
V M
VM
Goldberg
J U
JU
Yoo
B
B
Johnstone
D030201:Activin Receptors, Type I; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis* / Q000378:metabolism; D002454:Cell Differentiation; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism; D003094:Collagen / Q000096:biosynthesis; D018076:DNA, Complementary / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D015675:Osteocalcin / Q000096:biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1
C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D015675:Osteocalcin; D012313:RNA; D003094:Collagen; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; C000625843:Tgfbr1 protein, rat