title: In vitro mineralization of human mesenchymal stem cells on three-dimensional type I collagen versus PLGA scaffolds: a comparative analysis.
abstract: BACKGROUND
  Development of a tissue engineered bone graft requires efficient bioactivity screening of biomaterials in clinically relevant three-dimensional systems. The authors analyzed the relative osteogenic potential of two three-dimensional biomaterials--type I collagen and poly(L-lactide-co-glycolide) (PLGA)--to support in vitro mineralization of human mesenchymal stem cells.
  
  
  METHODS
  Human mesenchymal stem cells were seeded onto three-dimensional PLGA or type I collagen scaffolds; incubated in osteogenic media; and harvested at 1, 4, and 7 days. Messenger RNA expression was analyzed using quantitative real-time reverse-transcriptase polymerase chain reaction for osteogenic (i.e., alkaline phosphatase, osteocalcin, bone sialoprotein, Runx2/core binding factor α-1) and angiogenic (i.e., vascular endothelial growth factor and interleukin-8) markers. Alkaline phosphatase enzyme activity was measured at 4 and 7 days. Mineralization was detected by alizarin red staining and micro-computed tomographic imaging at 8 and 12 weeks. Mineral composition was analyzed by solid-phase nuclear magnetic resonance spectroscopy.
  
  
  RESULTS
  Early osteogenic and angiogenic markers, and alkaline phosphatase enzyme activity, were up-regulated on PLGA versus collagen scaffolds. However, long-term mineralization endpoints favored type I collagen. By 8 weeks, human mesenchymal stem cells on collagen exhibited significantly higher mineral density by micro-computed tomographic and alizarin red staining than PLGA scaffolds. Both biomaterials deposited calcium hydroxyapatite as determined by nuclear magnetic resonance spectroscopy.
  
  
  CONCLUSIONS
  The authors' findings suggest that despite early PLGA induction of osteogenic gene expression, long-term mineralization occurs earlier and to a greater extent on type I collagen, highlighting collagen as a potential bone tissue engineering scaffold in the human mesenchymal stem cell niche. When screening the relative osteoinductive profiles of three-dimensional bone tissue engineering scaffolds in vitro, the authors recommend including long-term endpoints of osteogenesis.
authors: Los Angeles and Torrance, Calif.; and Bronx, N.Y. From the Plastic Surgery Laboratory and the Research Service, Veterans Affairs Greater Los Angeles Healthcare System; the Division of Plastic and Reconstructive Surgery, Department of Surgery, and the Department of Medicine, David Geffen School of Medicine at the University of California, Los Angeles; Albert Einstein College of Medicine; and the Department of Surgery, Harbor-UCLA Medical Center.
authors: Erwin A
authors: EA
authors: Kruger
authors: Daniel D
authors: DD
authors: Im
authors: David S
authors: DS
authors: Bischoff
authors: Clifford T
authors: CT
authors: Pereira
authors: Weibiao
authors: W
authors: Huang
authors: George H
authors: GH
authors: Rudkin
authors: Dean T
authors: DT
authors: Yamaguchi
authors: Timothy A
authors: TA
authors: Miller
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