ABSTRACT
Intervertebral discs (IVDs) have poor nutrient diffusion, because the nucleus pulposus (NP) lacks direct vascular supply and likely generates adenosine triphosphate by anaerobic glycolysis. Regulation of glycolysis is mediated by hypoxia-inducible factor-1α (HIF-1α), a transcription factor that responds to local oxygen tension. Constitutively active HIF-1α (CA HIF-1α) was created by point mutation and determined the protective role of HIF-1α in IVD degeneration. Under fluoroscopy, rat caudal IVD segments were stabbed by a needle puncture, and pcDNA3- HIF-1α wild-type (WT) or pcDNA3-CA HIF-1α was transfected into NP cell lines. The constitutive activity of CA HIF-1α was analyzed using a luciferase assay after cell lysis. Next, IVD tissue samples were retrieved from five patients with degenerative lumbar spinal stenosis at the time of surgery, and NP cells were cultured. NP cells were transfected with CA HIF-1α, and relevant gene expression was measured. HIF-1α protein levels in the nucleus were significantly higher, and transcriptional activity was 10.3-fold higher in NP cells with CA HIF-1α than in those with HIF-1α WT. Gene transfer of CA HIF-1α into NP cells enhanced the expression of Glut-1, Glut-3, aggrecan, type II collagen, and Sox9. Moreover, CA HIF-1α reduced the apoptosis of NP cells induced by the Fas ligand. The HIF-1α and collagen 2 expression levels were notably increased in the NP cells of the CA HIF-1α transfected segments in histology and immunohistochemistry study. Collectively, these results suggest that activation of HIF-1α signaling pathway may play a protective role against IVD degeneration and could be used as a future therapeutic agent.
Subject(s)
Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Intervertebral Disc Degeneration/prevention & control , Animals , Cell Line , Collagen Type II/metabolism , Gene Expression/genetics , Gene Expression Regulation/genetics , Glycolysis , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/pharmacology , Intervertebral Disc/pathology , Male , Nucleus Pulposus/metabolism , Rats , Rats, Sprague-Dawley , Signal Transduction/physiologyABSTRACT
Hyperextension injury in the thoracic spine is uncommon with only a few cases documented in the literature. The mechanism of these injuries is hyperextension combined with axial or shearing force. These types of injuries are associated with a high risk of dural tears and paraplegia. A 91-year-old female presented with acute back pain from a hyperextension injury in thoracic spine with no neurological deficit. Lumbar magnetic resonance imaging showed a intervertebral disc rupture. On day 20 of hospitalization, the herniated intervertebral disc compressed the spinal cord with incomplete paraplegia. Hyperextension injuries involving the three columns are very unstable and we recommend surgical treatment as soon as possible, not only because of the initial trauma, but a ruptured disc herniation can damage the spinal cord.
