Background Low back pain has emerged as a widespread disease often caused by intervertebral disc degeneration.This study aimed to establish an in vitro cell culture model of rhesus monkey lumbar intervertebral discs and to investigate the effect of combined connective tissue growth factor （CTGF） and tissue inhibitor of metalloprotease-1（TIMP-1） expression mediated by adeno-associated virus （AAV） on collagen type Ⅱ and proteoglycan levels.The purpose of these investigations was to explore potential methods for relieving the degeneration of lumbar intervertebral disc cells.Methods Rhesus monkey lumbar intervertebral disc nucleus pulposus cells （NPCs） were isolated by enzyme digestion,cultured, and transduced with rAAV2-CTGF-IRES-TIMP-1, rAAV2-CTGF, or rAAV2-TIMP-1 at a multiplicity of infection （MOl） of 106.The expression of collagen type Ⅱ and proteoglycan was measured using RT-PCR and Western blotting.The synthetic rate of proteoglycan was measured using 35S incorporation.Results Rhesus monkey lumbar intervertebral disc NPCs were transduced with rAAV2-CTGF-IRES-TIMP-1,rAAV2-CTGF, and rAAV2-TIMP-1 and the transduced genes were expressed and detected.Compared to the control,CTGF promoted the synthesis of collagen type Ⅱ and proteoglycan.TIMP-1 showed an enhancing effect on the expression of proteoglycan but no effect on collagen type Ⅱ.Expression of both genes in rhesus monkey lumbar intervertebral disc NPCs significantly enhances the synthesis of proteoglycan and collagen type Ⅱ.Conclusions Single gene transduction of CTGF or TIMP-1 can enhanced synthesis of proteoglycan.CTGF expression can also enhance collagen type Ⅱ protein synthesis.Combined transduction of both CTGF and TIMP1 can significantly promote the expression of proteoglycan and collagen type Ⅱ to levels greater than transduction of a single gene alone.Our study provides a good basis for multi-gene therapy to treat lumbar intervertebral disc degeneration.
Background Intervertebral disc degeneration is the main cause of low back pain. The purpose of this study was to explore potential methods for reversing the degeneration of lumbar intervertebral discs by transplantation of gene-modified nucleus pulposus cells into rabbit degenerative lumbar intervertebral discs after transfecting rabbit nucleus pulposus cells with adeno-associated virus 2 （AAV2）-mediated connective tissue growth factor （CTGF） and tissue inhibitor of metalloproteinases 1 （TIMP1） genes in vitro. Methods Computer tomography （CT）-guided percutaneous annulus fibrosus injury was performed to build degenerative lumbar intervertebral disc models in 60 New Zealand white rabbits, rAAV2-CTGF-IRES-TIMPI-transfected rabbit nucleus pulposus cells were transplanted into degenerative lumbar intervertebral discs （transplantation group）, phosphate-buffered saline （PBS） was injected into degenerative lumbar intervertebral discs （degeneration control group） and normal lumbar intervertebral discs served as a blank control group. After 6, 10 and 14 weeks, the disc height index （DHI） and signal intensity in intervertebral discs were observed by X-ray and magnetic resonance imaging （MRI） analysis The expression of CTGF and TIMP1 in nucleus pulposus tissue was determined by Western blotting analysis, the synthesis efficiency of proteoglycan was determined by a 35S-sulfate incorporation assay, and the mRNA expression of type II collagen and proteoglycan was detected by RT-PCR. Results MRI confirmed that degenerative intervertebral discs appeared two weeks after percutaneous puncture. Transgenic nucleus pulposus cell transplantation could retard the rapid deterioration of the DHI. MRI indicated that degenerative intervertebral discs were relieved in the transplantation group compared with the degeneration control group. The expression of collagen II mRNA and proteoglycan mRNA was significantly higher in the transplantation group and the blank control group compared with the degeneration
