Caspase 3 as a therapeutic target for regulation of intervertebral disc degeneration in rabbits.

OBJECTIVE Although the etiology of intervertebral disc degeneration is poorly understood, one possible approach for its regulation is apoptosis inhibition. This study was undertaken to investigate the antiapoptotic effects of caspase 3 in intervertebral disc degeneration in rabbits. METHODS We investigated the effects of caspase 3 small interfering RNA (siRNA) on rabbit nucleus pulposus cells in a serum-starved medium. The effects of direct injection of Alexa Fluor 555-labeled caspase 3 siRNA into the intervertebral disc were also determined in vivo using the rabbit anular needle puncture model. RESULTS Rabbit nucleus pulposus cells transfected with caspase 3 siRNA showed a significant decrease in serum-starved apoptotic cells. After local injection of caspase 3 siRNA into intervertebral discs, red fluorescence was observed in the nucleus pulposus upon treatment with Alexa Fluor 555-labeled caspase 3 siRNA. Caspase 3 messenger RNA and protein were down-regulated in the caspase 3 siRNA group. Magnetic resonance imaging and histologic evaluation showed that degenerative changes were significantly suppressed in the caspase 3 siRNA group 4 and 8 weeks after injection. Quantification of TUNEL staining showed that the caspase 3 siRNA group had significantly fewer apoptotic nucleus pulposus cells than the control siRNA group. CONCLUSION Our findings indicate that caspase 3 knockdown in rabbit intervertebral disc cells is effective in preventing apoptotic cell death, thus regulating intervertebral disc degeneration.