title: Effects of chondrogenic and osteogenic regulatory factors on composite constructs grown using human mesenchymal stem cells, silk scaffolds and bioreactors.
abstract: Human mesenchymal stem cells (hMSCs) isolated from bone marrow aspirates were cultured on silk scaffolds in rotating bioreactors for three weeks with either chondrogenic or osteogenic medium supplements to engineer cartilage- or bone-like tissue constructs. Osteochondral composites formed from these cartilage and bone constructs were cultured for an additional three weeks in culture medium that was supplemented with chondrogenic factors, supplemented with osteogenic factors or unsupplemented. Progression of cartilage and bone formation and the integration between the two regions were assessed by medical imaging (magnetic resonance imaging and micro-computerized tomography imaging), and by biochemical, histological and mechanical assays. During composite culture (three to six weeks), bone-like tissue formation progressed in all three media to a markedly larger extent than cartilage-like tissue formation. The integration of the constructs was most enhanced in composites cultured in chondrogenic medium. The results suggest that tissue composites with well-mineralized regions and substantially less developed cartilage regions can be generated in vitro by culturing hMSCs on silk scaffolds in bioreactors, that hMSCs have markedly higher capacity for producing engineered bone than engineered cartilage, and that chondrogenic factors play major roles at early stages of bone formation by hMSCs and in the integration of the two tissue constructs into a tissue composite.
authors.affiliation: Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Augst
authors.forename: Darja
authors.initials: D
authors.lastname: Marolt
authors.forename: Lisa E
authors.initials: LE
authors.lastname: Freed
authors.forename: Charu
authors.initials: C
authors.lastname: Vepari
authors.forename: Lorenz
authors.initials: L
authors.lastname: Meinel
authors.forename: Michelle
authors.initials: M
authors.lastname: Farley
authors.forename: Robert
authors.initials: R
authors.lastname: Fajardo
authors.forename: Nipun
authors.initials: N
authors.lastname: Patel
authors.forename: Martha
authors.initials: M
authors.lastname: Gray
authors.forename: David L
authors.initials: DL
authors.lastname: Kaplan
authors.forename: Gordana
authors.initials: G
authors.lastname: Vunjak-Novakovic
mesh_terms: D000704:Analysis of Variance; D001205:Ascorbic Acid / Q000031:analogs & derivatives; D019149:Bioreactors; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D018929:Cell Culture Techniques / Q000379:methods*; D020219:Chondrogenesis / Q000502:physiology*; D003907:Dexamethasone; D005994:Glycerophosphates; D006801:Humans; D007150:Immunohistochemistry; D007328:Insulin; D008279:Magnetic Resonance Imaging; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D010012:Osteogenesis / Q000502:physiology*; D047011:Silk / Q000378:metabolism*; D023822:Tissue Engineering / Q000379:methods*; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D005994:Glycerophosphates; D007328:Insulin; D047011:Silk; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; C011669:ascorbate-2-phosphate; D003907:Dexamethasone; D001205:Ascorbic Acid; C031463:beta-glycerophosphoric acid