AO Spine Reference Centre & Institute of Health & Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. Traumatic spinal cord injury (SCI) is a devastating condition with no curative therapy. Pro-inflammatory therapy has been suggested recently to try and reduce the inhibitory glial scar and promote neural regeneration and healing. The aim of this study is to investigate the potential of sustained delivery of angiogenic/pro-inflammatory growth factors to reduce the secondary degeneration after spinal cord injury. Adult male Wistar Kyoto rats (200-300g; 12-16weeks old) were subjected to cord hemisections via a T10 laminectomy. Animals were randomised to treatment or control groups after the spinal cord injury had been induced. Treatment consisted of implantation of a mini-osmotic pump capable of delivering 5 micrograms vascular endothelial growth factor (VEGF) and 5 micrograms platelet-derived growth factor (PDGF), via a catheter, to the site of the lesion, over 7 days(n=6). Control animals were subjected to either cord lesion only (n=6) or lesion plus mini-pump delivering PBS (phosphate-buffered saline) solution (n=6). Rats were sacrificed at one month and the spinal cords were harvested and examined by immunohistology, using anti-neurofilament-200 and anti-Glial Acidic Fibrillary Acidic Protein (GFAP) antibodies. RESULTS: Active treatment spinal cords showed a higher level with aboration of the axonal filament through the defect and more dense neurofilament-200 staining at the lesion site compared to both control groups. The treatment also showed the elevated presence of activated microglia in the lesion, whilst distal to the lesion the microglia and astrocytes retained an unreactive phenotype. Pro-inflammatory therapy in the rat spinal cord-injury model showed favourable histological findings after sustained delivery of PDGF and VEGF

Mesenchymal stem-cell based therapies have been proposed as novel treatments for intervertebral disc degeneration, a prevalent and disabling condition associated with back pain. The development of these treatment strategies, however, has been hindered by the incomplete understanding of the human nucleus pulposus phenotype and by an inaccurate interpretation and translation of animal to human research. This review summarises recent work characterising the nucleus pulposus phenotype in different animal models and in humans and integrates their findings with the anatomical and physiological differences between these species. Understanding this phenotype is paramount to guarantee that implanted cells restore the native functions of the intervertebral disc.

Cite this article: Bone Joint Res 2013;2:169–78.