title: Biomechanical and Endplate Effects on Nutrient Transport in the Intervertebral Disc.
abstract: BACKGROUND
  Physical data are lacking on nutrient transport in human intervertebral discs (IVDs), which support regeneration. Our objective was to study nutrient transport in porcine IVDs to determine the effects of biomechanical and physiological factors.
  
  
  METHODS
  In vitro testing of whole porcine IVDs was performed under different loading conditions. Fifty cervical, thoracic, and lumbar discs with attached end plates were removed from 4 Yorkshire pigs (90-150 lbs). Discs were placed in Safranin O or Fast Green FCF histological stains in diffusion or diurnal compression-tested groups. The end plate was studied by the use of polyurethane to block it. Traction was studied with a mechanical testing frame. Discs were cut transversely and photographed. Images were analyzed for depth of annulus fibrosus (AF) stained. The nucleus pulposus (NP) was assigned a staining score.
  
  
  RESULTS
  Results showed no difference in AF staining between the 2 stains (P = 0.60). The depth of AF staining did not increase (P = 0.60) due to convection or disc height change via diurnal loading. The NP in all open end plate samples was stained completely by day 3. NP staining was decreased in blocked end plate samples (P = 0.07) and AF staining was significantly less in traction samples than in diffusion-only samples (P = 0.04).
  
  
  CONCLUSIONS
  This method showed that most small molecule nutrient transport occurs via the end plate. Compressive load was a negligible benefit or hindrance to transport. Traction hindered transport in the short term. This method can be used to study strategies for increasing nutrient transport in IVDs.
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
authors.forename: Morgan B
authors.initials: MB
authors.lastname: Giers
authors.affiliation: School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona, USA.
authors.forename: Bryce T
authors.initials: BT
authors.lastname: Munter
authors.affiliation: School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona, USA.
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Eyster
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
authors.forename: George D
authors.initials: GD
authors.lastname: Ide
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA; School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona, USA.
authors.forename: Anna G U S
authors.initials: AGUS
authors.lastname: Newcomb
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Lehrman
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA; Department of Neurosurgery, Irkutsk Scientific Center of Surgery and Traumatology, Irkutsk, Russia; Department of Neurosurgery, Irkutsk State University, Irkutsk, Russia.
authors.forename: Evgenii
authors.initials: E
authors.lastname: Belykh
authors.affiliation: Department of Neurosurgery, Irkutsk Scientific Center of Surgery and Traumatology, Irkutsk, Russia.
authors.forename: Vadim A
authors.initials: VA
authors.lastname: Byvaltsev
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Kelly
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Preul
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA. Electronic address: Neuropub@dignityhealth.org.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Theodore
mesh_terms: D000818:Animals; D000070616:Annulus Fibrosus / Q000378:metabolism / Q000502:physiology; D001692:Biological Transport / Q000502:physiology*; D001696:Biomechanical Phenomena; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000378:metabolism* / Q000502:physiology; D000070614:Nucleus Pulposus / Q000378:metabolism / Q000502:physiology; D012038:Regeneration / Q000502:physiology; D013314:Stress, Mechanical; D034421:Sus scrofa; D013552:Swine
chemical_list: D005947:Glucose
keywords: Annulus fibrosus; Biomechanics; Calcification; Cell function; Extracellular matrix; Intervertebral disc; Nucleus pulposus; Nutrient transport; Regeneration; Spine