Effect of Nutrient Concentration and OP-1 on the Metabolism of Intervertebral Disc: In Vitro Organ Culture Study

Using the in vitro organ culture system with endplate, 24 lumbar intervertebral discs from New Zealand rabbits were cultured over 21 days in different concentrations of fetal bovine serum (5%, 10%, and 20% FBS). 4 of the specimens cultured in 5% FBS were injected with 0.2 mg OP-1 at 7 days. At 21 days, discs were dissected from endplate and annulus fibrosus (AF) and nucleus pulposus (NP) were separated, and DNA and proteoglycan (PG) content were measured. We found that NP tissue is very sensitive to nutrient supply, wheras AF is not dependent on nutrition. In addition, OP-1 appears to protect NP tissue from undergoing degeneration from poor disc nutrition.