title: High Field Sodium MRI Assessment of Stem Cell Chondrogenesis in a Tissue-Engineered Matrix.
abstract: The development of non-invasive assessment techniques in vitro and in vivo is essential for monitoring and evaluating the growth of engineered cartilage tissues. Magnetic resonance imaging (MRI) is the leading non-invasive imaging modality used for assessing engineered cartilage. Typical MRI uses water proton relaxation times (T1 and T2) and apparent diffusion coefficient (ADC) to assess tissue growth. These techniques, while excellent in providing the first assurance of tissue growth, are unspecific to monitor the progress of engineered cartilage extracellular matrix components. In the current article, we present high field (11.7 T, (1)H freq. = 500 MHz) sodium MRI assessment of tissue-engineered cartilage at the early stage of tissue growth in vitro. We observed the chondrogenesis of human bone marrow derived stromal cells seeded in a gradient polymer-hydrogel matrix made out of poly(85 lactide-co-15 glycolide)--PuraMatrix™ for 4 weeks. We calculated the sodium concentration in the engineered constructs using a model of sodium MRI voxels that takes into account scaffold volume, cell density and amount of glycosaminoglycan (GAG). The sodium concentration was then converted to the fixed charge density (FCD) and compared with FCD derived from biochemical GAG analysis. Despite the small amount of GAG present in the engineered constructs, the sodium MRI derived FCD is found to be correlated (Pearson correlation coefficient R = 0.79) with the FCD derived from biochemical analysis. We conclude that sodium MRI could prove to be an invaluable tool in assessing engineered cartilage quantitatively during the repair or regeneration of cartilage defects.
authors.affiliation: Department of Bioengineering, University of Illinois at Chicago, 835 S. Wolcott St., W 110C, Chicago, IL, 60612, USA.
authors.forename: Shreyan
authors.initials: S
authors.lastname: Majumdar
authors.affiliation: Department of Bioengineering, University of Illinois at Chicago, 835 S. Wolcott St., W 110C, Chicago, IL, 60612, USA.
authors.forename: Padmabharathi
authors.initials: P
authors.lastname: Pothirajan
authors.affiliation: Orthopaedic Surgery and Department of Biomedical Engineering, University of Connecticut, Farmington, CT, 06030, USA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Dorcemus
authors.affiliation: Orthopaedic Surgery and Department of Biomedical Engineering, University of Connecticut, Farmington, CT, 06030, USA.
authors.forename: Syam
authors.initials: S
authors.lastname: Nukavarapu
authors.affiliation: Department of Bioengineering, University of Illinois at Chicago, 835 S. Wolcott St., W 110C, Chicago, IL, 60612, USA. mkotecha@uic.edu.
authors.forename: Mrignayani
authors.initials: M
authors.lastname: Kotecha
mesh_terms: D001861:Bone Regeneration; D002356:Cartilage / Q000254:growth & development*; D020219:Chondrogenesis; D004247:DNA / Q000032:analysis; D006025:Glycosaminoglycans / Q000032:analysis; D006801:Humans; D008279:Magnetic Resonance Imaging; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D012964:Sodium; D023822:Tissue Engineering; D054457:Tissue Scaffolds; D055114:X-Ray Microtomography
chemical_list: D006025:Glycosaminoglycans; D004247:DNA; D012964:Sodium
keywords: Bone marrow derived human mesenchymal stem cells; Cartilage tissue engineering; Fixed charge density; Polymer-hydrogel gradient scaffolds; Proteoglycans; Sodium MRI