A Comparison of Bone Marrow Derived and Adipose Derived Stem Cells in Point of Care Goat Non-Instrumented Posterolateral Intertransverse Spinal Fusion Daria Brigitte Neidre, Ph.D. The University of Texas at Austin, May, 2010 Supervisor: Roger P. Farrar Concentrated bone marrow containing mesenchymal stem cells (BMSCs) in combination with osteoconductive scaffolds has been used in orthopaedics to replace the need for iliac crest bone grafts. Autologous BMSC volume is limited, but adipose tissue represents a large reservoir of stem cells; adipose derived stem cells (ADSCs). To test these cells, a large animal model using goats was selected due to their similarities to humans in loading conditions of the spine, trabecular bone structure of the vertebrae, and their common use in testing orthopaedic therapies as a clinically relevant model. The aim of this study is to characterize cell surface markers of the isolated cells through flow cytometry, compare goat BMSCs and ADSCs using multilineage differentiation into the osteogenic and adipogenic lineages, and utilize them in a “Point-of-Care” non-instrumented posterolateral lumbar spinal fusion. Both BMSCs and ADSCs were confirmed as stem cells through lack of expression of markers CD34, CD45, CD90, and CD105, which is supported by literature. Both cell types also differentiated into both the adipogenic and osteogenic lineages. Although we had positive in vitro results, we had limited in vivo results. There were no differences between BMSCs, ADSCs and control implantation in identifiable spinal fusion at 3 or 6 months through radiographs or CT scans. Additionally, there were no differences between groups at 6 months in biomechanical testing, histology and microradiographs. Although our in vivo results were lacking in demonstrating fusion at 6 months, this study is the first of it’s kind to investigate a large animal model comparison of BMSCs and ADSCs in spinal fusion and demonstrated that “Point-of-Care” stem cells derived from either bone marrow or adipose tissue demonstrated the potential for bone formation. The in vivo results suggests that this model can be used for stem cell research in orthopaedics, but further research needs to be performed to determine their use, proper scaffold and potential osteoinductive materials needed for solid fusion results in the in vivo model. / text