A new culture system to study the metabolism of the intervertebral disc in vitro.

STUDY DESIGN

This study determined whether entrapment of a rabbit intervertebral disc in alginate gel helped to promote the retention of normal metabolic activities by the nucleus pulposus and anulus fibrosus in tissue culture.

OBJECTIVES

To establish an in vitro culture system to study the metabolism of the intervertebral disc as a whole integral organ.

SUMMARY OF BACKGROUND DATA

In vitro studies of the metabolism of intervertebral discs have been scarce because of the difficulties involved in maintaining the integrity of the tissues, especially that of the nucleus pulposus, in culture medium.

METHODS

Rabbit intervertebral discs were embedded in alginate gel and maintained in culture for as long as 1 month. At weekly intervals, experiments were performed to measure the rate of proteoglycan synthesis and to characterize proteoglycans newly synthesized by cells in the anulus fibrosus and nucleus pulposus. In addition, at these same time intervals, the contents of sulfated proteoglycans, antigenic keratan sulfate, hyaluronan, and collagen in these two intervertebral disc tissues were measured to evaluate tissue integrity. Intervertebral discs cultured in medium alone were used as controls and analyzed in parallel.

RESULTS

The anulus fibrosus and nucleus pulposus of intervertebral discs cultured in alginate gel sustained a higher rate of proteoglycan synthesis and maintained a higher content of extracellular matrix components than the respective controls at all times.

CONCLUSIONS

This new alginate tissue culture system should prove useful for studying the metabolism of whole intervertebral discs.