Transplantation of goat bone marrow stromal cells to the degenerating intervertebral disc in a goat disc-injury model

Study Design. In vivo, randomized, controlled study in the goat intervertebral disc (IVD) injury model. Objective. To define the effects of allogeneic bone marrow-derived stromal cell injected into the degenerating goat IVDs. Summary of Background Data. Transplantation of bone marrow stromal cells to the degenerating disc has been suggested as a means to correct the biologic incompetence of the disc. However, large animal models with IVDs similar in shape and size to those of humans are needed to define the efficacy and safety of this approach. Methods. Goat IVD degeneration was induced by stabbing with a number 15 blade. One month after disc injury, the injured discs were randomly selected to receive goat bone marrow-derived stromal cell (suspended in hydrogel), saline (control), or hydrogel (control) injections. At 3 and 6 months after stem cell transplantation, goats were killed and the IVD were examined for biochemical content and tissue morphology. Magnetic resonance images at 3- and 6-month time points were also examined. Results. The goat large animal model shows early degenerative changes following disc injury. Degenerating IVDs injected with bone marrow stromal cells showed significantly increased proteoglycan accumulation within their nucleus pulposus region. However, collagen content, magnetic resonance imaginggrade, and histology did not show statistically significant differences between the cell-treated and control IVDs. Conclusion. Following transplantation of bone marrow stromal cells, nucleus pulposus tissue contained more proteoglycan than control discs. Although this result was promising, the rate and severity of degeneration in this goat disc injury were modest, suggesting that a more severe injury and a larger sample size is indicated for future studies to better define the utility of cell therapies in this model.