Feasibility of using a human nucleus pulposus cell line as a cell source in cell transplantation therapy for intervertebral disc degeneration.

STUDY DESIGN: Assessment of the potential use of an immortalized human nucleus pulposus cell line as an alternative cell source in cell transplantation therapy for intervertebral disc degeneration.

OBJECTIVES: To evaluate the effect of transplanting the human nucleus pulposus cell line into a disc degeneration model in rabbits and to define whether it is capable of becoming an alternative cell source for cell transplantation therapy for disc degeneration.

SUMMARY OF BACKGROUND DATA: Interest in cell transplantation therapy for disc degeneration has been growing for several years, and a range of different cell types have been examined as possible donor cells. In addition, the establishment of a novel cell line that possesses some of the major characteristics of a normal human nucleus pulposus cells has been reported.

METHODS: Human nucleus pulposus cell line was established, and cells were transplanted into a rabbit disc degeneration model. At 4, 8, and 24 weeks after transplantation, inhibition of intervertebral disc degeneration was assessed by examining the disc height, macroscopic appearance, histologic findings, and immunohistochemistry. In addition, aggrecan, versican, and Type II collagen gene expression in the nucleus pulposus were measured semiquantitatively at the mRNA level. Furthermore, the survival of transplanted cells was examined using immunohistochemistry for Simian Virus 40 T antigen, and the presence of graft-versus-host reaction was assessed by immunohistochemistry for CD4 and CD58.

RESULTS: The disc height was significantly greater in the transplanted group than in the degenerative group's disc from 4 weeks' posttransplantation. Macroscopically, the nucleus pulposus was absent and there was loss of disc height in the degenerative group at 24 weeks after transplantation, whereas the nucleus pulposus was preserved in the transplanted group. Histologic examination showed that the structure of the inner anulus fibrosus was significantly preserved in the transplanted group, and the boundary between the nucleus and anulus could be clearly visualized. Expression of mRNAs of the nucleus pulposus matrix, aggrecan, and Type II collagen was significantly greater in the transplanted group than in the degenerative group. This indicates that transplantation of human nucleus pulposus cell line helped to preserve the matrix of the nucleus pulposus. Thus, transplantation of a human nucleus pulposus cell line was shown to delay disc degeneration in this rabbit model.

CONCLUSION: The human nucleus pulposus cell line may become an alternative cell source for cell transplantation therapy of intervertebral disc degeneration.