Abstract
Aims: Recent advances in our understanding of intervertebral disc biology have led to develop novel treatments for intervertebral disc degeneration (IDD). With the ability to provide sustained delivery of a potentially therapeutic agent, gene therapy has shown much promise in regard to the treatment of IDD. The aims of this study are (part 1) to test efficacy in delaying course of IDD by intrediscal injection of adenoviral vectors carrying human BMP-2 and (part 2) to describe the application of an inducible system in order to modulate transgene expression.
Methods: (Part 1) IDD was induced in 13 NZW rabbits by anterolateral stab. Three weeks post-stab, saline with or without virus was injected directly into stabbed lumbar discs. Group 1 (n=8) received Ad/hBMP-2 while group 2 (n=5) received saline only. Rabbits were followed longitudinally with MRIs and X-rays preoperatively for up to 12 weeks post-stab. ELISAs were done to confirm BMP-2 production. (Part 2) Human nucleus pulposus cells (NPC) were transduced with an adenoviral vector that expresses GFP under the control of a tetracycline (Ad/GFPtet). Cells were cultutred with and without tetracycline. Transgene expression was assessed by detecting GFP signal with both the FACS and the fluorescent microscope.
Results: (Part 1) By 12 weeks, the saline-injected discs had lost 49% of their MRI Index, in contrast to only a 25% decrease for the Ad/hBMP-2 treated discs. X-rays demonstrated no obvious bony intervertebral fusion in either group. ELISAs confirmed vigorous hBMP-2 production 3 weeks after therapeutic gene transfer. (Part 2) NPC expressed GFP after transduction. GFP positivity was not observed two days after administration of tetracycline. The cells expressed GFP again three days after removal of tetracycline.
Discussion: The results of this study demonstrate the efficacy of vector-mediated BMP-2 gene transfer to alter the course of IDD in a reproducible animal model, as well as the potential to control transgene expression, improving safety.
The abstracts were prepared by incoming Professor Elena Brach del Prever. Correspondence should be addressed to IORS – President office, Dipartimento di Traumatologia, Ortopedia e Mediciana del Lavoro, Centro Traumatologico Ortopedico - Via Zuretti, 29 I-10135 Torino, Italy.
