Proliferation potential of human lumbar disc after herniation

To investigate the regenerative potential of human disc tissue, the disc samples were obtained during surgery from 24 adult patients with first lumbar prolapses and from 14 patients with recurrent lumbar prolapses. Preoperative magnetic resonance imaging (MRI) confirmed prolapse and disc degeneration in all cases. The proliferation activity of the sampled connective tissue cells was studied with the immunohistochemical expression of Ki-67(MIB-1) antigen. The antigen was positive in 6 of 24 (25%) specimens from first prolapse and in none of the 14 specimens from the recurrent prolapse. The amount of proliferative cells did not correlate to the degree of disc degeneration in MRI. Our results indicate that connective tissue cells in adult degenerative disc may show proliferation activity after the first herniation and thus regenerative potential. The enhanced matrix proliferation may not be a significant reason for recurrent prolapses because none of the recurrent disc specimen showed proliferation activity.