BACKGROUND:Statins can promote the mRNA expression of bone morphogenetic protein 2, aggrecan and type II col agen in intervertebral disc cel s, and they also can reverse the phenotype of dedifferentiated nucleus pulposus cel s to slow disc degeneration process. OBJECTIVE:To review the research progress of simvastatin modulating the biological characteristics and mobilizing endogenous stem cel s for the repair of intervertebral disc degeneration. METHODS:The first author retrieved the PubMed and CNKI databases for relevant articles published before January 2016 using the key words of“disc degeneration factor, Simvastatin AND stem cel s, endogenous stem cel s AND disc degeneration”in English and Chinese, respectively. Initial y, 102 relevant articles were retrieved, but only 48 articles were included in result analysis fol owing elimination of duplicate studies.RESULTS AND CONCLUSION:By summarizing a large number of studies on the treatment of intervertebral disc degeneration worldwide, we found that simvastatin may modulate the biological characteristics and function of nucleus pulposus mesenchymal stem cel s via promoting the expression of hypoxia-inducible factor 1αfor the endogenous stem cel-based therapy of intervertebral disc degeneration.

Objective To compare the effect of different size needle gauges to the degenerative response in rat caudal discs.Methods A total of 40 Sprague Dawley (SD) rats,level 5/6,7/8 and 9/10 interverbral discs of rat caudal spine were punctured with 18 or 21 or 25-gauge needles respectively.Radiographs and magnetic resonance imaging (MRI) were obtained at 1,2,4 and 6 weeks postsurgery.At each time point,ten rats from each group were sacrificed for histological analysis.Real-time fluorescent quantitative polymerase chain reaction (qPCR) was used to examine mRNA expression level.Results Significant differences were identified in the disc height index (DHI ％) and MRI grade between 18 G and normal group,MRI grade,histological score between 21 G and normal group at 2,4,and 6 weeks postsurgery.Significant differences were also identified in the histological score and mRNA expression levels between 18 G and normal group,alcian blue stain and hypoxia inducible factor-1α (HIF-1 α) mRNA expression level between 21G and normal group at all time point postsurgery.Significant differences existed in DHI％,type Ⅱ collagen and aggrecan mRNA expression levels between 21 G and normal group,all type mRNA expression levels between 25 G and normal group at 4,6 weeks.There were significant differences in MRI grade and histological score between 25 G and normal group at 6 weeks.Significant differences existed in almost all parameters compared between 18 G and 25 G at all time point.There were significant differences in DHI％,MRI grade,histological score and HIF-1α mRNA expression levels between 18 G and 21 G at 4,6 weeks.There were significant differences in type Ⅱ collagen and aggrecan mRNA expression levels between 18 G and 21 G at all time point.Significant differences exist in DHI％ and HIF-1α mRNA expression level between 21 G and 25 G at 6 weeks.Compared with the 25 G group,the DHI％ and Pfirrmann scores and the pathological score of each time at 2,4 and 6 weeks after operation in 18 G group have significant difference (P ＜ 0.05).Conclusions The middle size needle (21G) is better to induce disc degeneration.The 2-week time point may be the better time frame to further experimental treatments.