title: The use of cultured bone marrow cells in type I collagen gel and porous hydroxyapatite for posterolateral lumbar spine fusion.
abstract: METHODS
  Posterolateral lumbar transverse process fusion was completed using the cultured bone marrow cells in type I collagen gel and porous hydroxyapatite.
  
  
  OBJECTIVE
  To compare the efficacy of cultured bone marrow cells with that of bone morphogenetic protein (BMP) as a graft alternative to autologous bone for posterolateral spine fusion.
  
  
  BACKGROUND
  The clinical application of BMP for spinal fusion may be limited by high dose and cost. Recently, mesenchymal stem cells have been studied in various fields because of their capability to differentiate into various cells, including those in the osteogenic lineage.
  
  
  METHODS
  Thirty adult rabbits were used. Each underwent single-level, bilateral, posterolateral intertransverse process fusions at L4-L5. The animals were divided into 4 groups, each according to the material implanted: (1) autologous bone (autograft, n = 9); (2) porous hydroxyapatite (HA) particles and type I collagen sheet with 100 microg rhBMP-2 (BMP-HA, n = 7); (3) bone marrow cells (1 x 10(6) cells/mL, low-marrow-HA, n = 7); and (4) bone marrow cells (1 x 10(8) cells/mL, high-marrow-HA, n = 7). Before implantation for groups 3 and 4, fresh bone marrow cells from the iliac crest of each animal were cultured in a standard medium for 2 weeks. For one additional week, the marrow cells were cultured in 10(-8) M dexamethasone, type I collagen gel, and HA. Animals were euthanized 6 weeks after surgery. Spinal fusions were evaluated by radiograph, manual palpation, and histology.
  
  
  RESULTS
  The fusion rates were 4 of 7 in the autograft group, 7 of 7 in the BMP-HA group, 0 of 7 in the low-marrow-HA group, and 5 of 7 in the high-marrow-HA group. The histology in the BMP-HA and high-marrow-HA groups showed that grafted HA fragments were connected with mature new bone. The pores of HA fragments were filled up with bone matrix. In the low-marrow-HA group, fibrous tissue was predominant in the grafted fragments.
  
  
  CONCLUSIONS
  This study shows that the cultured bone marrow cells can act as a substitute for autograft or BMP in spine fusion. The current formulation may yield improved fusion success and better quality of fusion bone as compared to autograft.
authors.affiliation: Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan. minamide@wakayama-med.ac.jp
authors.forename: Akihito
authors.initials: A
authors.lastname: Minamide
authors.forename: Munehito
authors.initials: M
authors.lastname: Yoshida
authors.forename: Mamoru
authors.initials: M
authors.lastname: Kawakami
authors.forename: Satoru
authors.initials: S
authors.lastname: Yamasaki
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Kojima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hashizume
authors.forename: Scott D
authors.initials: SD
authors.lastname: Boden
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation / Q000379:methods*; D018786:Bone Substitutes / Q000008:administration & dosage*; D002478:Cells, Cultured; D024042:Collagen Type I; D017886:Durapatite; D005782:Gels; D020007:Implants, Experimental; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D023421:Models, Animal; D016348:Osseointegration; D010012:Osteogenesis; D011817:Rabbits; D011859:Radiography; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods
chemical_list: D018786:Bone Substitutes; D024042:Collagen Type I; D005782:Gels; D017886:Durapatite