[Establishment of an in vitro model of natural degeneration of lumbar endplate chondrocytes and expression of Sox9 therein].
OBJECTIVE
To establish an in vitro model of natural degeneration of lumbar endplate chondrocytes and explore the role and the expression change of Sox9 gene, an important gene in the differentiation and maturation of chondrocyte, in the process of natural degeneration of endplate chondrocytes.


METHODS
The lumbar vertebrae of 35 SD rats were taken out to obtain the endplates. Endplate chondrocytes were isolated by enzyme digestion and cultured so as to establish an in vitro natural degeneration model of chondrocytes. The morphological appearances and biological characteristics of the chondrocytes of different generations were observed by HE staining, immunocytochemical staining and toluidine blue et cetera; RT-PCR was used to detect the mRNA expression of Sox9 gene and type II collagen in differential generations.


RESULTS
The lumbar cartilaginous endplate chondrocytes of rat expressed collagen II, and it's phenotype and biological characteristics were similar to those of articular cartilage cells. When the cells were passaged to the forth or fifth generations they were fusiform and their proliferative speed decreased. Compared with the primary generation chondrocytes, the expression of Sox9 mRNA in the forth and fifth generation chondrocytes was markedly decreased (P < 0.05). And the mRNA expression level of type II collagen, regulated by Sox9 gene, decreased too (P < 0.05). The mRNA expression of Sox9 was positively correlated with the mRNA expression of type II collagen (r = 0.912, P < 0.05).


CONCLUSIONS
A model of natural degeneration of lumbar endplate chondrocytes has been established successfully, thus providing a good cytological basis for the study of degeneration of lumbar endplate. Sox9 gene may play a role in the process of natural degeneration of endplate chondrocytes.
Xu
Hong-Guang
HG
Department of Orthopedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu 241001, China. xuhg@medmail.com.cn
Lai
Bi-Hua
BH
Chen
Xue-Wu
XW
Jin
Song
S
Wang
Hong
H
Liu
Ping
P
Wang
Ling-Ting
LT
Huang
De-Gang
DG
Bi
Fu-Yong
FY
D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism*; D019902:Chondrocytes / Q000378:metabolism*; D024043:Collagen Type II; D004195:Disease Models, Animal; D015870:Gene Expression; D007405:Intervertebral Disc Displacement / Q000378:metabolism*; D008159:Lumbar Vertebrae; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000235:genetics*
D024043:Collagen Type II; D012333:RNA, Messenger; D055758:SOX9 Transcription Factor