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01.08.2011 | Research article | Ausgabe 4/2011 Open Access

Arthritis Research & Therapy 4/2011

The efficacy of Link N as a mediator of repair in a rabbit model of intervertebral disc degeneration

Arthritis Research & Therapy > Ausgabe 4/2011
Fackson Mwale, Koichi Masuda, Rajeswari Pichika, Laura M Epure, Tomoaki Yoshikawa, Aseem Hemmad, Peter J Roughley, John Antoniou
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​ar3423) contains supplementary material, which is available to authorized users.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

FM conceived this study and wrote the manuscript. KM participated in the design of the study and performed the surgery. LME performed the biochemical analysis and statistical analysis, and was involved in preparation of the manuscript. RP, TY and AH performed data acquisition and statistical analysis. PJR participated in the design of the study and interpretation of the data, and revised the manuscript. JA made substantial contributions to the study design and revised the manuscript. All authors read and approved the final manuscript.



Intervertebral disc (IVD) degeneration is associated with proteolytic degradation of the extracellular matrix, and its repair requires both the production of extracellular matrix and the downregulation of proteinase activity. These properties are associated with several growth factors. However, the use of growth factors in clinical practice is limited by their high cost. This cost can be circumvented using synthetic peptides, such as Link N, which can stimulate the synthesis of proteoglycan and collagen by IVD cells in vitro. The purpose of the present study was to evaluate the effect of Link N in vivo in a rabbit model of IVD degeneration.


New Zealand white rabbits received annular puncture in two lumbar discs. Two weeks after puncture, both punctured discs of each rabbit were injected with either Link N or saline. After 2 weeks, nine rabbits were euthanized and the annulus fibrosus (AF) and nucleus pulposus (NP) of Link N-injected and saline-injected IVDs were removed and used to prepare total RNA. Following reverse transcription, quantitative PCR was performed for aggrecan, COL2A1, COL1A1, ADAMTS-4, ADAMTS-5 and MMP-3. After 12 weeks, 19 rabbits were euthanized and the injected IVDs were removed for biochemical and histological analysis. Proteinase K digests were analyzed for DNA and sulfated glycosaminoglycan content. Disc height was monitored radiographically biweekly.


Following needle puncture, disc height decreased by about 25% over 2 weeks, and was partially restored by Link N injection. Puncture of the IVD resulted in a trend towards decreased proteoglycan content in both the NP and AF, and a trend towards partial restoration following Link N injection, although under the time course used this did not achieve statistical significance. Link N did not alter the DNA content of the discs. Link N injection led to a significant increase in aggrecan gene expression and a significant decrease in proteinase gene expression in both the NP and AF, when compared with saline alone.


When administered to the degenerate disc in vivo, Link N stimulated aggrecan gene expression and downregulated metalloproteinase expression, and there was a trend towards increased proteoglycan content of the disc, in both the NP and AF. These are features needed for any agent designed to stimulate disc repair. In principle, therefore, Link N supplementation could be an option for treating disc degeneration.
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