Experimental intervertebral disc degeneration induced by fibronection fragment in rabbit

English Keywords:Intervertebral disc degeneration  Animial model  Fibronection fragment  White rabbits

English Abstract:

  【Abstract】 Objectives: To investigate the feasibility of establishing an experimental animal model by using N-terminal fibronection fragment(Fn-f) which induces the pathologic hallmarks of human intervertebral disc degeneration, and to facilitate the investigations of intervertebral disc degeneration. Methods: 25μl of 1.5μmol/L Fn-f or phosphate buffered saline(PBS) was injected into the central region of isolated lumbar discs in 28 male New Zealand white rabbits of six-month-old under a percutaneous X-guided by using a microsyringe with a 30-gauge needle. Euthanasia was performed at 4-, 8-, 12-, and 16-week, and the histology and gene expression of disc tissue was tested. Results: Histology studies revealed a progressive loss of the normal architecture of the nucleus pulposus(NP) and annulus fibrosus(NF) after injecting Fn-f during 16 weeks compared with PBS injected discs. The pathological sections of the NP region in Fn-f-treated discs at the 4th week showed plenty of nuclear cells clumped loosely with uniform distribution. And rich extracellular matrix was evidenced. At the 8th week, the number of nuclear cells decreased and clustered. At the 12th and 16th week, the Fn-f injected discs showed decreased nuclear cells number and proteoglycan matrix. The NP cells became rounded and clustered. The AF region of the Fn-f-treated discs demonstrated progressive loss of the normal lamellar organization and breakage. Significantly down-regulated expression of aggrecan gene in the Fn-f-treated discs was evidenced at the 8th week, 12th week and 16th week, and the expression of type-Ⅱcollagen gene in Fn-f-treated discs was significantly down-regulated at the 12th week and 16th week compared with PBS treated control discs. Conclusions: 30 kDa of N-terminal Fn-f injection into the central region of rabbit discs results in slowly progressive intervertebral disc degeneration, which is similar to that observed in human disc degeneration and can be used for further study.