The short-term effects of electrosurgical ablation on proinflammatory mediator production by intervertebral disc cells in tissue culture.
BACKGROUND
Percutaneous discectomy can be performed by a variety of methods. One method, electrosurgical ablation, has been shown in a chronic animal model to alter the expression of inflammatory cytokines in degenerated discs.


OBJECTIVE
To determine whether electrosurgical ablation has an acute direct effect on proinflammatory mediator production by disc cells.


METHODS
A short-term in vitro study using normal and interleukin (IL)-1alpha stimulated porcine disc cells cultured in alginate gel to evaluate the biochemical effects of electrosurgical ablation.


METHODS
Porcine annulus and nucleus cells were embedded into alginate gels and cultured using control culture media or IL-1alpha-treated media for 6 days before ablation treatment. Treated gels were ablated by using a radiofrequency-based electrosurgical device for 5 seconds and cultured an additional 3 or 6 days. IL-1beta, IL-6, IL-8, tumor necrosis factor alpha (TNF-alpha), prostaglandin E2 (PGE2), nitric oxide (NO), and heat shock protein-70 (Hsp70) levels in culture medium were measured. Levels were normalized to DNA and compared between ablated and shams.


RESULTS
For normal annulus cells, there were no significant changes in cytokine levels between ablation and sham groups. For normal nucleus cells, ablation produced significantly greater levels of IL-8 at 3 days and 6 days, Hsp70 at 3 days but not 6 days, and NO at 6 days. PGE2 was also increased at 3 days and 6 days but not significantly. For IL-1-stimulated annulus cells, IL-6 and NO in the ablation group were decreased at 3 days relative to the control group. However, IL-6, IL-8, PGE2, and Hsp70 were significantly increased in the 6-day ablation group. For degenerated nucleus cells, IL-6, IL-8, and TNF-alpha were significantly decreased in the ablation group at both 3 days and 6 days. Ablation resulted in reduced PGE2 at 3 days but not 6 and reduced Hsp70 and NO at 6 days.


CONCLUSIONS
The results show that electrosurgical ablation has an acute direct effect on proinflammatory mediator production by disc cells. The effect produced depends on disc cell phenotype, the mediator, and time. These direct biologic effects may be a mechanism of pain relief after percutaneous discectomy using electrosurgical ablation. However, the measured responses are limited to the short-term (1 week), and the existence of a prolonged effect remains to be determined.
Rhyu
Kee-Won
KW
Department of Orthopaedic Surgery, University of California at San Francisco, 2100 Webster Street, Suite 110, San Francisco, CA 94115, USA.
Walsh
Andrew J L
AJ
O'Neill
Conor W
CW
Bradford
David S
DS
Lotz
Jeffrey C
JC
D000818:Animals; D017115:Catheter Ablation; D002478:Cells, Cultured; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D015232:Dinoprostone / Q000096:biosynthesis; D004598:Electrosurgery / Q000379:methods; D050884:HSP72 Heat-Shock Proteins / Q000096:biosynthesis; D018836:Inflammation Mediators / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053582:Interleukin-1alpha / Q000494:pharmacology; D007403:Intervertebral Disc / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000601:surgery*; D013552:Swine; D013997:Time Factors
D016207:Cytokines; D050884:HSP72 Heat-Shock Proteins; D018836:Inflammation Mediators; D053582:Interleukin-1alpha; D015232:Dinoprostone