title: Osteogenic differentiation of human mesenchymal stem cells in mineralized alginate matrices.
abstract: Mineralized biomaterials are promising for use in bone tissue engineering. Culturing osteogenic cells in such materials will potentially generate biological bone grafts that may even further augment bone healing. Here, we studied osteogenic differentiation of human mesenchymal stem cells (MSC) in an alginate hydrogel system where the cells were co-immobilized with alkaline phosphatase (ALP) for gradual mineralization of the microenvironment. MSC were embedded in unmodified alginate beads and alginate beads mineralized with ALP to generate a polymer/hydroxyapatite scaffold mimicking the composition of bone. The initial scaffold mineralization induced further mineralization of the beads with nanosized particles, and scanning electron micrographs demonstrated presence of collagen in the mineralized and unmineralized alginate beads cultured in osteogenic medium. Cells in both types of beads sustained high viability and metabolic activity for the duration of the study (21 days) as evaluated by live/dead staining and alamar blue assay. MSC in beads induced to differentiate in osteogenic direction expressed higher mRNA levels of osteoblast-specific genes (RUNX2, COL1AI, SP7, BGLAP) than MSC in traditional cell cultures. Furthermore, cells differentiated in beads expressed both sclerostin (SOST) and dental matrix protein-1 (DMP1), markers for late osteoblasts/osteocytes. In conclusion, Both ALP-modified and unmodified alginate beads provide an environment that enhance osteogenic differentiation compared with traditional 2D culture. Also, the ALP-modified alginate beads showed profound mineralization and thus have the potential to serve as a bone substitute in tissue engineering.
authors.affiliation: Kristian Gerhard Jebsen Center for Myeloma Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Marita
authors.initials: M
authors.lastname: Westhrin
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Minli
authors.initials: M
authors.lastname: Xie
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Magnus Ø
authors.initials: MØ
authors.lastname: Olderøy
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Pawel
authors.initials: P
authors.lastname: Sikorski
authors.affiliation: Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Berit L
authors.initials: BL
authors.lastname: Strand
authors.affiliation: Kristian Gerhard Jebsen Center for Myeloma Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway; Centre of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Therese
authors.initials: T
authors.lastname: Standal
mesh_terms: D000464:Alginates / Q000378:metabolism; D000704:Analysis of Variance; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology*; D020723:Glucuronic Acid / Q000378:metabolism; D006603:Hexuronic Acids / Q000378:metabolism; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D010012:Osteogenesis / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020723:Glucuronic Acid