P23. Reconstruction of a Tissue-Specific Extracellular Matrix for Enhancing Nucleus Pulposus Cell Proliferation and Redifferentiation Capacity Ming Pei, PhD, Fan He, BA, Scott D. Daffner, MD, John C. France, MD; West Virginia University, Morgantown, WV, USA BACKGROUND CONTEXT: Low back pain is often related to interver- tebral disc (IVD) degeneration that results from a progressive loss of pro- teoglycans and water content in the nucleus pulposus (NP). Autologous disc cell-based therapy is a promising approach for IVD regeneration. Un- fortunately, the current in vitro expansion of NP cells in monolayer results in dedifferentiation of these cells. PURPOSE: Synovium-derived stem cells (SDSCs) are a tissue-specific stem cell for cartilage-like tissue regeneration. Since NP cells are chondrocyte-like cells, it is speculated that a more tissue-specific three-dimensional (3D) microenvironment deposited by SDSCs can maintain the phenotype of seeded NP cells during ex vivo expansion instead of standard 2D culture. STUDY DESIGN/SETTING: In this study, SDSCs were used to prepare extracellular matrix (ECM). Primary NP cells were plated either on regular plastic flasks or on ECM-coated flasks for six consecutive passages. METHODS: At each passage, cell numbers were counted for proliferation rate, cell phenotype was evaluated using flow cytometry and cell differen- tiation status was assessed using real time PCR. At passages 1, 4, and 6, the expanded NP cells were centrifuged to form pellets and incubated in a chondrogenic medium. Redifferentiation capacity of the expanded NP cells was evaluated using histology, biochemistry, and real time PCR. RESULTS: Our study showed that NP cells grown on SDSC-derived ECM were smaller with a more fibroblast-like shape and grew much faster com- pared to NP cells expanded on plastic flasks. The percentage and mean fluorescent intensity (MFI) of CD90 were increased in ECM-treated NP cells despite a decrease in CD29 MFI. ECM-treated NP cells retained high- er mRNA levels of types I, II, and X collagen and aggrecan. ECM-treated NP cells also acquired a very strong redifferentiation capacity, evidenced by dramatically increased type II collagen, aggrecan and Sox9 as well as decreased type I collagen in passage 6 NP cell-pellets in the presence of serum-free chondrogenic medium. CONCLUSIONS: Our study indicates that SDSC-derived ECM can pro- vide a tissue-specific microenvironment for the rejuvenation of NP cells with a higher proliferation rate and redifferentiation capacity, which may play a role in improving an autologous disc cell-based minimally invasive therapeutic approach toward physiological reconstruction of a biologically functional disc in a clinical setting. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2010.07.299 P24. Disc Height Restoration after Transforaminal Lumbar Interbody Fusion: Is There a Correlation with Clinical Outcomes? Jennifer Kaur R. Sohal, MD 1 , Steven D. Glassman, MD 1 , Robert J. Woodruff, MD 2 , Leah Y. Carreon, MD, MSc 1 ; 1 Norton Leatherman Spine Center, Louisville, KY, USA; 2 University of Louisville School of Medicine Department of Orthopedic Surgery, Louisville, KY, USA BACKGROUND CONTEXT: One of the theoretical advantages of a transforaminal lumbar interbody fusion (TLIF) is that indirect decom- pression of the exiting nerve root, and therefore improvement of radiculop- athy, can be achieved by elevation of the disc space. The actual achievement of disc space height elevation and correlation with improve- ment in clinical outcomes after TLIF has not been evaluated. PURPOSE: To determine whether TLIF produces disc height elevation and to determine if disc height elevation is associated with improved clin- ical outcomes. STUDY DESIGN/SETTING: Retrospective review. PATIENT SAMPLE: Patients from a single spine center who underwent a single-level TLIF with a minimum two-year follow-up. OUTCOME MEASURES: Radiographic outcomes included measure- ments of segmental lumbar lordosis and anterior disc height and posterior disc height. Functional outcomes included the Oswestry Disability Index (ODI), Short Form-36 Physical Composite Summary Score (SF-36 PCS), and numeric rating scales (0–10) for back pain and leg pain. METHODS: Patients who had a single-level TLIF with a minimum two- year follow-up were identified. Using a digital caliper, pre-operative and most recent follow-up standing lateral lumbar radiographs were measured to determine segmental lumbar lordosis, anterior disc space height, and pos- terior disc space height. Paired t-tests were used to compare the pre-operative and follow-up radiographic measures and clinical outcome measures. Pa- tients were classified into whether or not they achieved minimum clinically important difference (MCID) for ODI, SF-36 PCS, back and leg pain. Inde- pendent sample t-tests were used to determine differences in radiographic measures between patients who did and did not achieve MCID. RESULTS: There were 85 patients (29 male, 56 female) with a mean age of 51611 years. There was no statistically significant difference between the pre- operative and follow-up segmental lordosis and anterior disc height. Posterior disc height was statistically significantly greater on follow-up compared to pre-operative (5.8 mm vs. 7.3 mm, p50.000). There were statistically signif- icant improvements in all outcome measures from pre-operative to follow-up. Patients who achieved MCID for ODI ($12.8 point improvement) had a statis- tically significant greater change in posterior disc height from pre-operative to follow-up compared to those who did not achieve MCID for ODI (2.4 mm vs. 0.6 mm, p50.019). Patients who achieved MCID for SF-36 PCS ($4.9 point improvement), back pain ($2 point improvement), and leg pain ($1 point im- provement) had a greater change in posterior disc height from pre-operative to follow-up compared to those who did not achieve MCID but this did not reach statistical significance. CONCLUSIONS: TLIF produces elevation of the posterior disc height, but does not change anterior disc height or produce segmental lumbar lor- dosis. Elevation of posterior disc height was greater in patients who achieved MCID compared to those that did not. This suggests that eleva- tion of posterior disc height by at least 2 mm may be important in achiev- ing good results after TLIF. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2010.07.300 P25. Xenogenic Cues for Human Mesenchymal Stem Cell Differentiation towards a Nucleus Pulposus Cell-like Phenotype Jeremy Mercuri, MS 1 , Sonny Gill, MD 2 , Agneta Simionescu, PhD 1 , Dan Simionescu, PhD 1 ; 1 Department of Bioengineering - Clemson University, Clemson, SC, USA; 2 Orthopedic Surgery - Steadman Hawkins Clinic, Frisco, CO, USA BACKGROUND CONTEXT: Tissue engineered nucleus pulposus re- placements are being developed as an early-stage therapeutic option for mitigating the progression of intervertebral disc degeneration. One key ele- ment to this strategy is finding a suitable cell source that mimics the healthy nucleus pulposus cell (NPC). Indirect contact co-culture of human mesen- chymal stem cells (hMSCs) with allogenic NPCs has been established as a promising approach for differentiating hMSCs towards an NPC-like phe- notype. Clinical realization of such a technique would require significant numbers of healthy allogenic NPCs, however the feasibility of harvesting and in-vitro expansion of adequate NPC quantities remain challenging. PURPOSE: To investigate the use of xenogenic NPCs as an alternative cell source to facilitate the differentiation of hMSCs. METHODS: Porcine NPCs were harvested and expanded in monolayer using standard cell culture conditions. Conditioned media (NPC-CM) re- moved from NPCs every 2–3 days during feeding was retained and added to fresh culture media in a 50/50 (v/v) ratio which was used to feed human adipose derived stem cells (hADSCs) in monolayer cultures. hADSCs and porcine NPCs cultured in standard cell culture conditions served as 114S Proceedings of the NASS 25th Annual Meeting / The Spine Journal 10 (2010) 1S–149S All referenced figures and tables will be available at the Annual Meeting and will be included with the post-meeting online content.