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Osteogenic differentiation of human mesenchymal stem cells in mineralized alginate matrices.

Westhrin M, Xie M, Olderøy MØ, Sikorski P, Strand BL, Standal T - PLoS ONE (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Kristian Gerhard Jebsen Center for Myeloma Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.

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.

No MeSH data available.


Related in: MedlinePlus

SEM micrographs of collagen fibrils in beads cultured in osteogenic medium.(A, C) low and high magnification of the space close to a cell producing collagen in ALP modified beads (ALP+). Mineral crystals similar to those shown in Fig. 2 are indicated by *; (B, D) low and high magnification micrographs of the space close to a cell producing collagen in unmineralized beads. Images were collected at 21 days post encapsulation.
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pone.0120374.g004: SEM micrographs of collagen fibrils in beads cultured in osteogenic medium.(A, C) low and high magnification of the space close to a cell producing collagen in ALP modified beads (ALP+). Mineral crystals similar to those shown in Fig. 2 are indicated by *; (B, D) low and high magnification micrographs of the space close to a cell producing collagen in unmineralized beads. Images were collected at 21 days post encapsulation.

Mentions: To investigate whether the cells influenced the material properties during the culture period by e.g. secreting matrix proteins, beads from all 4 sample groups and cells from traditional culture plate (2D) samples were examined by SEM after 21days of culture. SEM microscopy revealed that cells in both ALP-modified (Fig. 4A and C) and unmodified alginate beads (Fig. 4B and D) cultured in osteogenic medium produce significant amounts of well organized, fibrillar collagen, which seemed to be located in the pericellular space between the cell surface and the alginate matrix (Fig. 4). The fibrils had diameters in the range of 100 nm and showed periodicity of 60–70 nm along the fibril axis typical for collagen type I (Fig. 4C and D). [24–26]. We did not observe collagen fibrils in beads cultured in growth medium (data not shown) suggesting that the 3D environment itself was not sufficient to promote collagen production. In the sample cultured in osteogenic medium on traditional culture plate (2D) no collagen fibrils was observed neither, but this could be due to it being washed away during media change or due to sample preparation for SEM (data not shown).


Osteogenic differentiation of human mesenchymal stem cells in mineralized alginate matrices.

Westhrin M, Xie M, Olderøy MØ, Sikorski P, Strand BL, Standal T - PLoS ONE (2015)

SEM micrographs of collagen fibrils in beads cultured in osteogenic medium.(A, C) low and high magnification of the space close to a cell producing collagen in ALP modified beads (ALP+). Mineral crystals similar to those shown in Fig. 2 are indicated by *; (B, D) low and high magnification micrographs of the space close to a cell producing collagen in unmineralized beads. Images were collected at 21 days post encapsulation.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358956&req=5

pone.0120374.g004: SEM micrographs of collagen fibrils in beads cultured in osteogenic medium.(A, C) low and high magnification of the space close to a cell producing collagen in ALP modified beads (ALP+). Mineral crystals similar to those shown in Fig. 2 are indicated by *; (B, D) low and high magnification micrographs of the space close to a cell producing collagen in unmineralized beads. Images were collected at 21 days post encapsulation.
Mentions: To investigate whether the cells influenced the material properties during the culture period by e.g. secreting matrix proteins, beads from all 4 sample groups and cells from traditional culture plate (2D) samples were examined by SEM after 21days of culture. SEM microscopy revealed that cells in both ALP-modified (Fig. 4A and C) and unmodified alginate beads (Fig. 4B and D) cultured in osteogenic medium produce significant amounts of well organized, fibrillar collagen, which seemed to be located in the pericellular space between the cell surface and the alginate matrix (Fig. 4). The fibrils had diameters in the range of 100 nm and showed periodicity of 60–70 nm along the fibril axis typical for collagen type I (Fig. 4C and D). [24–26]. We did not observe collagen fibrils in beads cultured in growth medium (data not shown) suggesting that the 3D environment itself was not sufficient to promote collagen production. In the sample cultured in osteogenic medium on traditional culture plate (2D) no collagen fibrils was observed neither, but this could be due to it being washed away during media change or due to sample preparation for SEM (data not shown).

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Kristian Gerhard Jebsen Center for Myeloma Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.

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.

No MeSH data available.


Related in: MedlinePlus