title: Multi-modal imaging for assessment of tissue-engineered bone in a critical-sized calvarial defect mouse model.
abstract: Tissue-engineered bone (TEB) analysis in vivo relies heavily on tissue histological and end-point evaluations requiring the sacrifice of animals at specific time points. Due to differences in animal response to implanted tissues, the conventional analytical methods to evaluate TEB can introduce data inconsistencies. Additionally, the conventional methods increase the number of animals required to provide an acceptable statistical power for hypothesis testing. Alternatively, our non-invasive optical imaging allows for the longitudinal analysis of regenerating tissue, where each animal acts as its own control, thus reducing overall animal numbers. In our 6 month feasibility study, TEB, consisting of a silk protein scaffold with or without differentiated mesenchymal stem cells, was implanted in a critical-sized calvarial defect mouse model. Osteogenesis of the TEB was monitored through signal variation, using magnetic resonance imaging (MRI) and near-infrared (NIR) optical imaging with IRDye® 800CW BoneTagTM(800CW BT, a bone-specific marker used to label osteogenically differentiated mesenchymal stem cells and mineralization). Histological endpoint measurements and computed tomography (CT) were used to confirm imaging findings. Anatomical MRI revealed decreased signal intensity, indicating mineralization, in the TEB compared to the control (i.e. silk scaffold only) at various growth stages. NIR optical imaging results demonstrated a signal intensity increase of the TEB compared to control. Interpretation of the imaging results were confirmed by histological analysis. Specifically, haematoxylin and eosin staining revealing de novo bone in TEB showed that 80% of the defect was covered by TEB, while only 40% was covered for the control. Taken together, these results demonstrate the potential of multi-modal non-invasive imaging to visualize and quantify TEB for the assessment of regenerative medicine strategies. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Wartella
authors.affiliation: Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA.
authors.forename: V
authors.initials: V
authors.lastname: Khalilzad-Sharghi
authors.affiliation: Department of Pharmacy Practice, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Kelso
authors.affiliation: LI-COR Biosciences, Biology Research and Development, Lincoln, NE, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Kovar
authors.affiliation: Department of Biomedical Engineering, Tufts University, Medford, MA, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Kaplan
authors.affiliation: School of Engineering and Computer Science, University of the Pacific, Stockton, CA, USA.
authors.forename: H
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA.
authors.forename: S F
authors.initials: SF
authors.lastname: Othman
mesh_terms: D000818:Animals; D018786:Bone Substitutes; D004195:Disease Models, Animal; D006801:Humans; D008279:Magnetic Resonance Imaging; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D051379:Mice; D061848:Optical Imaging; D010012:Osteogenesis; D012886:Skull / Q000000981:diagnostic imaging / Q000293:injuries; D023822:Tissue Engineering; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D018786:Bone Substitutes
keywords: IRDye 800CW BoneTag; calvarial defect model; magnetic resonance imaging (MRI); near-infrared optical imaging; tissue-engineered bone (TEB)