title: Physiologic load-bearing characteristics of autografts, allografts, and polymer-based scaffolds in a critical sized segmental defect of long bone: an experimental study.
abstract: BACKGROUND
  To address the challenge of treating critical sized intercalary defects, we hypothesized that under physiologic cyclic loading, autografts, allografts, and scaffolds loaded with and without human mesenchymal stem cells (hMSCs) would have different biomechanical characteristics.
  
  
  METHODS
  Using a rat femoral defect model, 46 rats were assigned to four groups, ie, autograft (n = 12), allograft (n = 10), scaffold (n = 13), and scaffold with hMSCs (n = 11). The scaffold groups used a 5 mm segment of scaffold composed of 80% poly-ε-caprolactone and 20% hydroxyapatite. Rats were sacrificed 4 months postoperatively, and the repairs were assessed radiographically and biomechanically.
  
  
  RESULTS
  Autograft and allograft groups exhibited the most bridging callus, while the scaffold/hMSCs group had more callus than the scaffold repairs. Although signs of radiographic healing did not accurately reflect restoration of mechanical properties, addition of hMSCs on the scaffold enhanced bone formation. The scaffold alone group had significantly lower elastic and viscous stiffness and higher phase angles than other repairs and the contralateral controls. Addition of hMSCs increased the elastic and viscous stiffness of the repair, while decreasing the phase angle.
  
  
  CONCLUSIONS
  Further comparative analysis is needed to optimize clinical use of scaffolds and hMSCs for critical sized defect repairs. However, our results suggest that addition of hMSCs to scaffolds enhances mechanical simulation of native host bone.
authors: Center for Orthopaedic Research, Columbia University Medical Center, New York, NY 10032, USA.
authors: L F
authors: LF
authors: Amorosa
authors: C H
authors: CH
authors: Lee
authors: A B
authors: AB
authors: Aydemir
authors: S
authors: S
authors: Nizami
authors: A
authors: A
authors: Hsu
authors: N R
authors: NR
authors: Patel
authors: T R
authors: TR
authors: Gardner
authors: A
authors: A
authors: Navalgund
authors: D-G
authors: DG
authors: Kim
authors: S H
authors: SH
authors: Park
authors: J J
authors: JJ
authors: Mao
authors: F Y
authors: FY
authors: Lee
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D018786:Bone Substitutes / Q000737:chemistry; D017886:Durapatite / Q000737:chemistry; D005260:Female; D005264:Femoral Fractures / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D005269:Femur / Q000293:injuries / Q000473:pathology / Q000502:physiology; D017102:Fracture Healing / Q000502:physiology*; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000502:physiology; D011091:Polyesters / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D023822:Tissue Engineering / Q000295:instrumentation* / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry; D014180:Transplantation / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D018786:Bone Substitutes; D011091:Polyesters; C016240:polycaprolactone; D017886:Durapatite
keywords: fracture healing; human mesenchymal stem cells; scaffolds; tissue engineering
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