Results

1. Department of Orthopaedic Surgery and Rehabilitation Medicine SUNY Downstate Medical Center, 450 Clarkson Ave Brooklyn, NY 11203 Introduction Influences of the Vertebral Endplate Microvasculature on the Development of Degenerative Disc Diseases: A Preliminary Study F. Xavier MD MS, S. Hossain BS, R. Rousseau, D. Chatterjee MD, G. Feuer MS, W. Hayes MS, and S. Saha PhD The vertebral cartilage endplate represents the main flow path to and from the nucleus pulposus[6,7]. The capillaries end in loops at the vertebral trabecular-endplate junction[8]. Senescence of the avascular nucleus with decreased transport of nutrients is thought to lead to degenerative disc diseases (DDD) and LBP. However, no study has explored the role of the microvessels’ structure in the development of DDD. We therefore investigated the correlation between cartilage endplate microvasculature and the level of DDD. Abstract Materials & Methods Discussion References Results Acknowledgments An average of 70% of all Americans will suffer from one episode of low back pain (LBP) in their lifetime[1]. Senescence of the avascular nucleus pulposus with decreased transport of nutrients is thought to lead to degenerative disc diseases (DDD) and low back pain[2-5]. We investigated the relationship between aging, cartilage endplate microvasculature, and the level of disc degeneration. Lumbar discs with adjacent endplates were harvested from three fresh young bovine and three embalmed human cadaveric spines. After tissue processing, histology, and staining, microscopic features of endplate vascular channels were visualized under light microscopy and measured using ImageJ. Our preliminary data showed a 15% decrease in the vascular channel count at the interface between subchondral bone and cartilage endplate from the bovine to the elderly human specimens. Moreover, we observed a 67% increase in endplate thickness and a 70% decrease in cross sectional vascular area in the human subjects. Keywords: Low back pain, Degenerative disc disease, Microvessels, Cartilage endplate, disc nutrition Figure 2. Sagittal view of the central region from a decalcified bovine lumbar vertebral endplate (Thickness: 70 microns; Magnification: 10X). Lumbar IVDs with adjacent endplates were harvested from three fresh young bovine (obtained from a local meat market) and three embalmed human [average age: 85 y.o.] cadaveric spines (donated by the Anatomy Lab at SUNY Downstate) [Fig. 1]. Specimens were stored at -20º C. Radiographs of whole spines was done before tissue processing [Fig. 4]. Histologic slides were prepared after fixation, decalcification, and cryosection [Fig. 2-4]. Staining was done with hematoxylin, safranin O, and fast green. Microscopic features of the endplate vascular channels were visualized under light microscopy and measured using ImageJ software. Figure 3. Sagittal view of the central region from a decalcified bovine lumbar vertebral endplate (Thickness: 70 microns; Magnification: 10X). An average of 10 vascular buds terminate at the cartilage endplate. Staining with hematoxylin, safranin O, and fast green reveals the fine histologic features. Figure 4. Lateral human lumbar spine radiograph showing the L4-L5 disc with adjacent vertebrae (left). The box indicates the portion used for the histological study. Sagittal view (right) of the central region of the L5 superior endplate (Thickness: 60 microns; Magnification: 10X). Note the increase in endplate thickness without vascular channels crossing it. We acknowledge the contributions of Drs. E. Ledet, R. Guilbert, S. Marquez, and J. Libien. None of the authors has received any outside financial support related to the subject of this investigation. Figure 1. Sagittal view of L4-L5 and L5-S1 discs from an embalmed human cadaveric spine (a). Axial (b) and sagittal (c) views of lumbar bovine discs. 1. Aaos. Burden of Musculoskeletal Diseases in the United States: Prevalence, Societal and Economic Cost. Amer Academy of Orthopaedic, 2008. 2. Urban JPG, Holm S, Maroudas A, and Nachemson A. "Nutrition of the intervertebral disc: effect of fluid flow on solute transport." Clinical orthopaedics and related research 170 (1982): 296-302. 3. Carreon LY, Ito T, Yamada M, Uchiyama S, and Takahashi HE. “Neovascularization induced by anulus and its inhi-bition by cartilage endplate. Its role in disc absorption.” Spine 22 (1997):1429–1434; discussion 1446–1427. 4. Ozaki S, Muro T, Ito S, Mizushima M. “Neovascu-larization of the outermost area of herniated lumbar inter-vertebral discs.” J OrthopSci 4 (1999):286–292. 5. Pai RR, D’sa B, Raghuveer CV, and Kamath A. “Neo-vascularization of nucleus pulposus. A diagnostic feature of intervertebral disc prolapse.” Spine 24 (1999):739–741. 6. Ogata K and Whiteside L. "Nutritional pathways of the intervertebral disc: an experimental study using hydrogen washout technique.“ Spine 6.3 (1981): 211-216. 7. Holm S, Maroudas A, Urban JPG, Selstam G, and Nachemson A. "Nutrition of the intervertebral disc: solute transport and metabolism."Connective tissue research 8, no. 2 (1981): 101-119. • 8. Crock HV and Goldwasser M. "Anatomic studies of the circulation in the region of the vertebral end-plate in adult Greyhound dogs." Spine 9, no. 7 (1984): 702-706. • 9. Alini M, Eisenstein SM, Ito K, Little C, Kettler A, Masuda K, and Wilke HJ."Are animal models useful for studying human disc disorders/degeneration?." European Spine Journal 17, no. 1 (2008): 2-19. These preliminary data showed a 15% decrease in the number of microvessels at the interface subchondral bone and cartilage endplate between young bovine and elderly human specimens. Moreover, we observed a 67% increase in endplate thickness and a 70% decrease in cross sectional vascular area in the human subjects. Animal models have been used over the years to study the human spine biomechanics. However, one needs to consider the biological and structural differences among species[9]. Our preliminary study compared the endplate microstructure of fresh bovine and embalmed human cadaveric vertebrae. These changes in endplate thickness and vascular surface area could play a synergistic role in limiting the nucleus pulposus nutrition leading to DDD in adult humans. We are currently collecting data from lumbar endplates from 20 different human cadaveric spines. Correlations between the above microvasculature parameters, vertebral bone morphometric characteristics, biomechanical properties, and patients’ history will be assessed.