Original Article
Synergistic effect of nanomaterials and BMP-2 signalling in inducing osteogenic differentiation of adipose tissue-derived mesenchymal stem cells

https://doi.org/10.1016/j.nano.2014.09.008Get rights and content

Abstract

The lack of complete understanding in the signalling pathways that control the osteogenic differentiation of mesenchymal stem cells hinders their clinical application in the reconstruction of large bone defects and non-union bone fractures. The aim of this study is to gain insight into the interactions of bone morphogenetic protein-2 (BMP-2) and bone biomimetic scaffolds in directing osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (ASCs) and the underlying signalling pathways involved. We demonstrated that bioactive glass nanoparticles (nBG) incorporated polycaprolactone (PCL) coating on hydroxyapatite/β-tricalcium phosphate (HA/TCP) scaffold exerted a synergistic effect with 3 days of BMP-2 treatment in promoting osteogenic gene expression levels (Runx-2, collagen I, osteopontin and bone sialoprotein) and alkaline phosphatase activity in ASCs. Furthermore, we revealed that the synergistic effect was mediated through a mechanism of activating β1-integrin and induction of Wnt-3a autocrine signalling pathways by nBG incorporated scaffold.

From the Clinical Editor

The aim of this study was to gain insight into the interactions of bone morphogenetic protein-2 and bone biomimetic scaffolds in directing osteogenic differentiation of adipose tissue-derived mesenchymal stem cells and the underlying signaling pathways involved.

Graphical abstract

Illustration of how bone structure biomimetic nBG-PCL/HA/TCP scaffolds synergize BMP-2 signalling to promote osteogenic differentiation in ASCs through a mechanism of activation β1 integrin and Wnt-3a autocrine signalings.

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Section snippets

Culturing of ASCs

ASCs (purchased from Invitrogen) were propagated until passage 4 according to the manufacturer's instructions in MesenPRO RSTM Basal Medium (Invitrogen) supplemented with 2 mM l-glutamine and MesenPRO RS Growth Supplement (Invitrogen). ASCs at passage 4 were used for all experiments.

Fabrication of HA/TCP and nBG-PCL/HA/TCP scaffolds

The method of fabricating HA/TCP and nBG-PCL/HA/TCP scaffolds have been previously described in detail.15 Briefly, calcium phosphate deficient apatite powder was prepared by an aqueous precipitation reaction and

3 days of BMP-2 pre-conditioning induced osteogenic differentiation of ASCs

Compared to ASCs without BMP-2 pre-conditioning, ASCs treated with BMP-2 (50 ng/ml) for 3 days showed significantly higher levels of Runx-2, collagen type I, osteopontin, and bone sialoprotein gene expression (Figure 1, A-D) and ALP enzyme activity (Figure 1, E) at 4 and 14 days, compared to ASCs without BMP-2.

nBG-PCL/HA/TCP scaffold surface supported the attachment and growth of ASCs

The surface of nBG-PCL/HA/TCP scaffolds were characterised by SEM analysis. Spherical-shaped nBG with average size of 20-50 nm in diameter were well dispersed on the nBG-PCL/HA/TCP scaffold

Discussion

This study was aimed to gain insight into the interactions between BMP-2 and nBG-PCL/HA/TCP scaffold in directing osteogenic differentiation of ASCs and the underlying signalling pathways that dictates ASCs fate, so that we are able to create such conditions for bone tissue regeneration. We demonstrated that the BMP-2 and nBG-PCL/HA/TCP scaffolds had a synergistic effect in inducing osteogenic differentiation in ASCs by involving a mechanism of activating β1-integrin and induction of Wnt-3a

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  • Cited by (0)

    The authors acknowledge the Australian National Health and Medical Research Council (NHMRC) and the Faculty of Engineering and IT at University of Sydney, for funding this project. The authors also acknowledge the Rebecca Cooper Foundation, and the facilities provided by School of AMME and the Bosch Institute at the University of Sydney.

    Conflicts of interest: There are no interest conflicts to declare.

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