Autologous intervertebral disc cell implantation -: A model using Psammomys obesus, the sand rat

Study Design. Work presented here used a small animal model to illustrate the feasibility of autologous disc cell implantation. Objectives. To develop a small animal model for autologous disc cell implantation. Summary of the Background Data. The use of autologous disc cells in the potential treatment of disc degeneration offers attractive possibilities for novel therapies. Results are presented on the use of the sand rat (Psammomy obesus); a small rodent that spontaneously develops disc degeneration during aging, in experimental studies in which cells were harvested from a lumbar intervertebral disc, expanded in monolayer tissue culture, labeled with agents that allow subsequent immunolocalization of these cells, and implanted a second disc site of of the donor animal. Methods. Tissue culture disc surgery, histology, and immunocytochemistry were used. Cells were either engrafted in a bioresorbable carrier tested for cell compatibility or injected into the recipient disc. Results were assessed with radiographic examination of the implantation site and with histology and immunocytochemistry. Conclusion. Data from 15 animals were obtained with engraftment resident in the animal for up to 33 weeks. Immunocytologic identification of engrafted cells showed that they integrated into the disc and were surrounded by normal matrix at time points up to 8 months postengraftment. Engrafted cells exhibited either a spindle-shaped morphology in the annulus or a rounded chondrocyte-like morphology in the nucleus. Although technically challenging, the authors' experience showed that autologous disc cell implantation can be successful and that the sand rat is a valuable model for autologous disc cell studies.