title: Magnetic Resonance Imaging of Human Tissue-Engineered Adipose Substitutes.
abstract: Adipose tissue (AT) substitutes are being developed to answer the strong demand in reconstructive surgery. To facilitate the validation of their functional performance in vivo, and to avoid resorting to excessive number of animals, it is crucial at this stage to develop biomedical imaging methodologies, enabling the follow-up of reconstructed AT substitutes. Until now, biomedical imaging of AT substitutes has scarcely been reported in the literature. Therefore, the optimal parameters enabling good resolution, appropriate contrast, and graft delineation, as well as blood perfusion validation, must be studied and reported. In this study, human adipose substitutes produced from adipose-derived stem/stromal cells using the self-assembly approach of tissue engineering were implanted into athymic mice. The fate of the reconstructed AT substitutes implanted in vivo was successfully followed by magnetic resonance imaging (MRI), which is the imaging modality of choice for visualizing soft ATs. T1-weighted images allowed clear delineation of the grafts, followed by volume integration. The magnetic resonance (MR) signal of reconstructed AT was studied in vitro by proton nuclear magnetic resonance ((1)H-NMR). This confirmed the presence of a strong triglyceride peak of short longitudinal proton relaxation time (T1) values (200 ± 53 ms) in reconstructed AT substitutes (total T1=813 ± 76 ms), which establishes a clear signal difference between adjacent muscle, connective tissue, and native fat (total T1 ~300 ms). Graft volume retention was followed up to 6 weeks after implantation, revealing a gradual resorption rate averaging at 44% of initial substitute's volume. In addition, vascular perfusion measured by dynamic contrast-enhanced-MRI confirmed the graft's vascularization postimplantation (14 and 21 days after grafting). Histological analysis of the grafted tissues revealed the persistence of numerous adipocytes without evidence of cysts or tissue necrosis. This study describes the in vivo grafting of human adipose substitutes devoid of exogenous matrix components, and for the first time, the optimal parameters necessary to achieve efficient MRI visualization of grafted tissue-engineered adipose substitutes.
authors.affiliation: 1 Division of Regenerative Medicine, CHU de Québec Research Centre , Québec, Canada .|2 Département de Chirurgie, Centre de Recherche en Organogenèse Expérimentale de l'Université Laval/LOEX , Québec, Canada .
authors.forename: Maryse
authors.initials: M
authors.lastname: Proulx
authors.affiliation: 1 Division of Regenerative Medicine, CHU de Québec Research Centre , Québec, Canada .|2 Département de Chirurgie, Centre de Recherche en Organogenèse Expérimentale de l'Université Laval/LOEX , Québec, Canada .
authors.forename: Kim
authors.initials: K
authors.lastname: Aubin
authors.affiliation: 1 Division of Regenerative Medicine, CHU de Québec Research Centre , Québec, Canada .
authors.forename: Jean
authors.initials: J
authors.lastname: Lagueux
authors.affiliation: 3 Département de Chimie, Université Laval , Québec, Canada .
authors.forename: Pierre
authors.initials: P
authors.lastname: Audet
authors.affiliation: 3 Département de Chimie, Université Laval , Québec, Canada .|4 Centre de Recherche sur les Matériaux Avancés (CERMA), Université Laval , Québec, Canada .|5 Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Université Laval , Québec, Canada .
authors.forename: Michèle
authors.initials: M
authors.lastname: Auger
authors.affiliation: 1 Division of Regenerative Medicine, CHU de Québec Research Centre , Québec, Canada .|4 Centre de Recherche sur les Matériaux Avancés (CERMA), Université Laval , Québec, Canada .|6 Département de Génie des Mines, de la Métallurgie et des Matériaux, Université Laval , Québec, Canada .
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Fortin
authors.affiliation: 1 Division of Regenerative Medicine, CHU de Québec Research Centre , Québec, Canada .|2 Département de Chirurgie, Centre de Recherche en Organogenèse Expérimentale de l'Université Laval/LOEX , Québec, Canada .
authors.forename: Julie
authors.initials: J
authors.lastname: Fradette
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D000818:Animals; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008819:Mice, Nude; D066244:Proton Magnetic Resonance Spectroscopy; D023822:Tissue Engineering