title: Spinal fusion using adipose stem cells seeded on a radiolucent cage filler: a feasibility study of a single surgical procedure in goats.
abstract: OBJECTIVE
  To assess the feasibility of a one-step surgical concept, employing adipose stem cells (ASCs) and a novel degradable radiolucent cage filler (poly-L-lactide-co-caprolactone; PLCL), within polyetheretherketone cages in a stand-alone caprine spinal fusion model.
  
  
  METHODS
  A double-level fusion study was performed in 36 goats. Four cage filler groups were defined: (i) acellular PLCL, (ii) PLCL + SVF (freshly harvested stromal vascular fraction highly enriched in ASCs); (iii) PLCL + ASCs (cultured to homogeneity); and (iv) autologous iliac crest bone graft (ABG). Fusion was assessed after 3 and 6 months by radiography, micro-CT, biomechanics, and biochemical analysis of tissue formed inside the cage after 6 months.
  
  
  RESULTS
  No adverse effects were observed in all groups. After 3 months, similar and low fusion rates were found. Segmental stability did not differ between groups in all tested directions. Micro-CT imaging revealed significantly higher amounts of mineralized tissue in the ABG group compared to all others. After 6 months, interbody fusion rates were: PLCL 53%, SVF 30%, ASC 43% and ABG 63%. A trend towards higher mineralized tissue content was found for the ABG group. Biochemical and biomechanical analyses revealed equal maturity of collagen cross-links and similar segmental stability between all groups.
  
  
  CONCLUSIONS
  This study demonstrates the technical feasibility and safety of the one-step surgical procedure for spinal fusion for the first time. The radiolucent PLCL scaffold allowed in vivo monitoring of bone formation using plain radiography. Addition of stem cells to the PLCL scaffolds did not result in adverse effects, but did not enhance the rate and number of interbody fusions under the current conditions. A trend towards superior results with ABG was found. Further research is warranted to optimize the spinal fusion model for proper evaluation of both PLCL and stem cell therapy.
authors.affiliation: Department of Orthopaedic Surgery, VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands, rjkroeze@yahoo.com.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kroeze
authors.forename: Theo H
authors.initials: TH
authors.lastname: Smit
authors.forename: Pieter P
authors.initials: PP
authors.lastname: Vergroesen
authors.forename: Ruud A
authors.initials: RA
authors.lastname: Bank
authors.forename: Reinout
authors.initials: R
authors.lastname: Stoop
authors.forename: Bert
authors.initials: B
authors.lastname: van Rietbergen
authors.forename: Barend J
authors.initials: BJ
authors.lastname: van Royen
authors.forename: Marco N
authors.initials: MN
authors.lastname: Helder
mesh_terms: D020341:Absorbable Implants; D000273:Adipose Tissue / Q000166:cytology*; D000818:Animals; D005240:Feasibility Studies; D006041:Goats; D007085:Ilium / Q000637:transplantation; D008159:Lumbar Vertebrae / Q000601:surgery; D023421:Models, Animal; D016348:Osseointegration; D011091:Polyesters; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D033581:Stem Cell Transplantation; D017154:Stromal Cells / Q000637:transplantation; D023822:Tissue Engineering
chemical_list: D011091:Polyesters; C033616:poly(lactide)