title: The use of fluorescence-labeled mesenchymal stem cells in poly(lactide-co-glycolide)/hydroxyapatite/collagen hybrid graft as a bone substitute for posterolateral spinal fusion.
abstract: BACKGROUND
  Posterolateral spinal fusion is used to treat patients with degenerative spinal disorders. In this study, we investigated the effectiveness of a mesenchymal stem cell (MSC)/hydroxyapatite/type I collagen hybrid graft for posterolateral spinal fusion in a rabbit model.
  
  
  METHODS
  In vitro study, the hybrid graft was cultured in complete or osteogenic medium for 7 days and 14 days and examined by scanning electron microscopy. The alkaline phosphatase activity of the MSCs was assessed and the expression of osteogenic gene was determined by reverse transcription polymerase chain reaction. In vivo investigation, spinal fusion was examined using radiography, manual palpation, computed tomography, torsional loading tests, and histologic analysis. Furthermore, using a PKH fluorescence labeling system, we examined whether the newly formed bone was derived from the transplanted MSCs.
  
  
  RESULTS
  Our data suggested that the MSCs differentiated into osteoblasts and produced extracellular matrix in the hybrid graft. Increased alkaline phosphatase activity was noted and mRNA of Cbfa-1 and osteopontin were detected. Radiographs and computed tomography images showed a continuous bone bridge and a satisfactory fusion mass incorporated into the transverse processes. The results of manual palpation and biomechanical data did not significantly differ between the two groups. Histologic examination of both groups revealed the presence of cartilage and endochondral ossification in the gaps between the grafted fragments. In situ tracing of the PKH 67-labeled MSCs indicated that the transplanted MSCs were partly responsible for the new bone formation.
  
  
  CONCLUSIONS
  The hybrid graft could be effectively used to achieve posterolateral spinal fusion.
authors.affiliation: Department of Orthopedics, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Jau-Wen
authors.initials: JW
authors.lastname: Huang
authors.forename: Song-Shu
authors.initials: SS
authors.lastname: Lin
authors.forename: Lih-Huei
authors.initials: LH
authors.lastname: Chen
authors.forename: Shih-Jung
authors.initials: SJ
authors.lastname: Liu
authors.forename: Chi-Chien
authors.initials: CC
authors.lastname: Niu
authors.forename: Li-Jen
authors.initials: LJ
authors.lastname: Yuan
authors.forename: Chi-Chuan
authors.initials: CC
authors.lastname: Wu
authors.forename: Wen-Jer
authors.initials: WJ
authors.lastname: Chen
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D016026:Bone Marrow Transplantation; D018786:Bone Substitutes; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000494:pharmacology*; D017886:Durapatite / Q000494:pharmacology*; D005453:Fluorescence; D017102:Fracture Healing / Q000187:drug effects; D019344:Lactic Acid / Q000494:pharmacology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology / Q000601:surgery; D045164:Mesenchymal Stem Cell Transplantation; D008855:Microscopy, Electron, Scanning; D009930:Organic Chemicals / Q000494:pharmacology; D016348:Osseointegration / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects; D010173:Palpation; D011100:Polyglycolic Acid / Q000494:pharmacology*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013123:Spinal Fusion / Q000379:methods*; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing
chemical_list: D018786:Bone Substitutes; D009930:Organic Chemicals; C451241:PKH67; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D003094:Collagen; D017886:Durapatite; D000469:Alkaline Phosphatase