Notochordal cells influence gene expression of inflammatory mediators of annulus fibrosus cells in proinflammatory cytokines stimulation.
OBJECTIVE
Notochordal cells in the intervertebral disc interact with nucleus pulposus (NP) cells and support the maintenance of disc homeostasis by regulation of matrix production. However, the influence of notochordal cells has not been evaluated in the annulus fibrosus (AF), which is the primary pain generator in the disc. We hypothesized that the notochordal cell has the capacity to modulate inflammatory mediators secreted by AF cells secondary to stimulation.


METHODS
Notochordal and AF cells were isolated from adult New Zealand white rabbits. AF pellets were cultured with notochordal cell clusters or in notochordal cell-conditioned media (NCCM) for 24 or 48 hours with proinflammatory cytokines at varying concentrations. Gene expression in AF pellets were assayed for nitric oxide synthase (iNOS), cyclo-oxygenase (COX)-2, and interleukin (IL)-6 by real time reverse transcriptase polymerase chain reaction (RT-PCR).


RESULTS
AF pellet in NCCM significantly decreased the iNOS and COX-2 messenger ribonucleic acid (mRNA) levels compared to AF pellets alone and AF pellets with notochordal cells (p < 0.05). AF pellet resulted in dose-dependent iNOS and COX-2 expression in response to IL-1beta, stimulation, demonstrating that 1 ng/ml for 24 hours yielded a maximal response. AF pellet in NCCM significantly decreased the expression of iNOS and COX-2 in response to 1ng/ml IL-1beta, stimulation at 24 hours (p < 0.05). There was no difference in IL-6 expression compared to AF pellets alone or AF pellets with notochordal cell clusters.


CONCLUSIONS
We conclude that soluble factors from notochordal cells mitigate the gene expression of inflammatory mediators in stimulated AF, as expected after annular injury, suggesting that notochordal cells could serve as a novel therapeutic approach in symptomatic disc development.
Moon
Hong Joo
HJ
Department of Neurosurgery, College of Medicine, Korea University, Seoul, Korea.
Joe
Hoon
H
Kwon
Taek Hyun
TH
Choi
Hye-Kyoung
HK
Park
Youn Kwan
YK
Kim
Joo Han
JH