Detrimental effects of discectomy on intervertebral disc biology can be decelerated by growth factor treatment during surgery: a large animal organ culture model.

ABSTRACT

BACKGROUND CONTEXT Lumbar discectomies are common surgical interventions that treat radiculopathy by removing herniated and loose intervertebral disc (IVD) tissues. However, remaining IVD tissue can continue to degenerate resulting in long-term clinical problems. Little information is available on the effects of discectomy on IVD biology. Currently, no treatments exist that can suspend or reverse the degeneration of the remaining IVD. PURPOSE: To improve the knowledge on how discectomy procedures influence IVD physiology and to assess the potential of growth factor treatment as an augmentation during surgery. STUDY DESIGN: To determine effects of discectomy on IVDs with and without transforming growth factor beta 3 (TGFß3) augmentation using bovine IVD organ culture. METHODS: This study determined effects of discectomy with and without TGFß3 injection using 1-, 6-, and 19-day organ culture experiments. Treated IVDs were injected with 0.2 µg TGFß3 in 20 µL phosphate-buffered saline+bovine serum albumin into several locations of the discectomy site. Cell viability, gene expression, nitric oxide (NO) release, IVD height, aggrecan degradation, and proteoglycan content were determined. RESULTS: Discectomy significantly increased cell death, aggrecan degradation, and NO release in healthy IVDs. Transforming growth factor beta 3 injection treatment prevented or mitigated these effects for the 19-day culture period. CONCLUSIONS: Discectomy procedures induced cell death, catabolism, and NO production in healthy IVDs, and we conclude that post-discectomy degeneration is likely to be associated with cell death and matrix degradation. Transforming growth factor beta 3 injection augmented discectomy procedures by acting to protect IVD tissues by maintaining cell viability, limiting matrix degradation, and suppressing NO. We conclude that discectomy procedures can be improved with injectable therapies at the time of surgery although further in vivo and human studies are required.