OBJECTIVETo investigate the role of transforming growth factor (TGF)-beta1 in degeneration of the ligamentum flavum in the lumbar spine.

METHODSThe degenerative ligamentum flavum was obtained during surgery from 8 patients with lumbar spinal stenosis (mean age 58.6 years), and 8 young patients (mean age 24.2 years) with acute lumbar disc herniation were included as normal controls. The thickness of the ligamentum flavum was measured on preoperative magnetic resonance images, and the mRNA expressions of type-I collagen and TGF-beta1 in the ligamentum flavum were detected using reverse transcriptase-polymerase chain reaction. The protein expression and localization of TGF-beta1 were investigated by Western blotting and immunohistochemical staining, respectively.

RESULTSThe thickness of the ligamentum flavum were 4.70-/+0.40 mm in the degenerative group and 2.50-/+0.36 mm in the control group, showing significant difference between the two groups (P<0.001). The type-I collagen mRNA expression in the degenerative group was significantly higher than that in the control group (P=0.007). The mRNA and protein expressions of TGF-beta1 were significantly higher in the degenerative group than in the control group (P=0.008 and 0.004, respectively). Immunohistochemistry showed that TGF protein was localized in the fibroblasts within the ligamentum flavum.

CONCLUSIONDegenerative ligamentum flavum shows hypertrophy and fibrosis, and TGF-beta1 overexpression may be associated with in the development and progression of ligamentum flavum degeneration in the lumbar spine.

Adult ; Aged ; Female ; Humans ; Hypertrophy ; pathology ; Intervertebral Disc Degeneration ; metabolism ; pathology ; Ligamentum Flavum ; metabolism ; pathology ; Lumbar Vertebrae ; Magnetic Resonance Imaging ; Male ; Middle Aged ; RNA, Messenger ; genetics ; metabolism ; Spinal Stenosis ; metabolism ; pathology ; Transforming Growth Factor beta1 ; genetics ; metabolism ; Young Adult

OBJECTIVETo investigate the role of platelet-derived growth factor-BB (PDGF-BB) in the degeneration of the hypertrophied ligamentum flavum (LF) in the lumbar spine.

METHODSSurgical specimens of degenerative hypertrophied LF were obtained from 11 patients with lumbar spinal stenosis (LSS, mean age 57.8 years), with those from 10 age-matched patients with lumbar disc herniation (LDH, mean age 53.5 years) as the normal controls. The thickness of the LF was measured preoperatively by axial T1-weighted magnetic resonance imaging (MRI) at the facet joint level. Immunohistochemistry was employed to determine the expression of PDGF β and PDGF-BB in the LF. The mRNA and protein expressions of PDGF-BB in the LF were detected using real-time PCR and Western blotting, respectively.

RESULTSThe thickness of the LF was 5.30±1.12 mm in the degenerative group and 2.80±1.53 mm in the control group, showing a significant difference between the two groups (P<0.001). PDGF-β and PDGF-BB were positive in the fibroblasts in hypertrophied LF. The mRNA and protein expressions of PDGF-BB were significantly higher in the degenerative group than in the control group (P=0.013 and 0.023, respectively).

CONCLUSIONThe high expression of PDGF-BB in the hypertrophied LF suggests its important role in the development of hypertrophy of LF in lumbar spinal canal stenosis.

Adult ; Aged ; Female ; Humans ; Hypertrophy ; metabolism ; Intervertebral Disc Degeneration ; metabolism ; pathology ; Ligamentum Flavum ; metabolism ; pathology ; Lumbar Vertebrae ; Male ; Middle Aged ; Proto-Oncogene Proteins c-sis ; metabolism ; Spinal Stenosis ; metabolism ; pathology

BACKGROUND: One of the characteristics of spinal stenosis is elastin degradation and fibrosis of the extracellular matrix of the ligamentum flavum. However, there have been no investigations to determine which biochemical factors cause these histologic changes. So we performed the current study to investigate the hypothesis that matrix metalloproteinases (MMPs), which possess the ability to cause extracellular matrix remodeling, may play a role as a mediator for this malady in the ligamentum flavum. METHODS: The ligamentum flavum specimens were surgically obtained from thirty patients with spinal stenosis, as well as from 30 control patients with a disc herniation. The extents of ligamentum flavum elastin degradation and fibrosis were graded (grade 0-4) with performing hematoxylin-eosin staining and Masson's trichrome staining, respectively. The localization of MMP-2 (gelatinase), MMP-3 (stromelysin) and MMP-13 (collagenase) within the ligamentum flavum tissue was determined by immunohistochemistry. The expressions of the active forms of MMP-2, MMP-3 and MMP-13 were determined by western blot analysis, and the blots were quantified using an imaging densitometer. The histologic and biochemical results were compared between the two conditions. RESULTS: Elastin degradation and fibrosis of the ligamentum flavum were significantly more severe in the spinal stenosis samples than that in the disc herniation samples (3.14 +/- 0.50 vs. 0.55 +/- 0.60, p < 0.001; 3.10 +/- 0.57 vs. 0.76 +/- 0.52, p < 0.001, respectively). The expressions of the active form of MMPs were identified in all the ligamentum flavums of the spinal stenosis and disc herniation patients. The expressions of active MMP-2 and MMP-13 were significantly higher in the spinal stenosis samples than that in the disc herniation samples (both p < 0.05). The expression of active MMP-3 was slightly higher in the spinal stenosis samples than that in the disc herniation samples, but the difference was not statistically significant (p = 0.131). MMP-2, -3, and -13 were positively stained on the ligamentum flavum fibroblasts. CONCLUSIONS: The current results suggest that the increased expression of active MMPs by the ligamentum flavum fibroblasts might be related to the elastin degradation and fibrosis of the ligamentum flavum in the patients who suffer with lumbar spinal stenosis.
Aged ; Blotting, Western ; Elastin/*metabolism ; Extracellular Matrix/metabolism/pathology ; Female ; Fibrosis ; Humans ; Immunohistochemistry ; Ligamentum Flavum/*metabolism/pathology ; *Lumbar Vertebrae ; Male ; Matrix Metalloproteinase 13/metabolism ; Matrix Metalloproteinase 2/metabolism ; Matrix Metalloproteinase 3/metabolism ; Matrix Metalloproteinases/*metabolism ; Middle Aged ; Spinal Stenosis/*metabolism/pathology