Abstract: AIM: To observe the effect of small molecule drug kartogenin (KGN) on promoting extracellular matrix secretion in endplate cartilage, and explore its protective role in the endplate cartilage or intervertebral disc degeneration. METHODS: Established an in vitro organ culture model of rat intervertebral disc, punctured the annulus and cultured in vitro. The rats were divided into three groups: control group, degeneration group and KGN treated group. The change of histomorphology in intervertebral disc tissue was assessed by HE staining, the extracellular matrix of endplate cartilage was observed by safranin O-fast green staining. The expressions of type Ⅱ collagen, proteoglycans and SOX-9 in the three groups were detected by Real time-PCR. The expressions of typeⅡCollagen and SOX-9 protein were measured by western blot.RESULTS: HE staining indicated that the nucleus disappeared and the endplate cartilage tended to thin in the degeneration group, and the disc structure is more complete after KGN treated; safranin O- fast green staining showed that the secretion of extracellular matrix were increased in the KGN treated group. Realtime-PCR showed type Ⅱcollagen, aggrecan, and SOX-9 mRNA levels were significantly reduced in the degeneration group, and the cartilage-related gene increased after KGN treated; Western blot results showed similar changes. CONCLUSION: Small molecule drug KGN can promote the extracellular matrix secretion in the endplate cartilage in order to protect the endplate cartilage and intervertebral disc degeneration.

Key words: intervertebral disc, endplate chondrocytes, degeneration, kartogenin