In vivo bioluminescence imaging study to monitor ectopic bone formation by luciferase gene marked mesenchymal stem cells

Background: BMP9 induces both osteogenic and adipogenic differentiation of mesenchymal stem cells (MSCs). Nell1 is a secretory glycoprotein with osteoinductive and anti-adipogenic activities. We investigated the role of Nell1 in BMP9-induced osteogenesis and adipogenesis in MSCs. Methods: Previously characterized MSCs iMEFs were used. Overexpression of BMP9 and NELL1 or silencing of mouse Nell1 was mediated by adenoviral vectors. Early and late osteogenic and adipogenic markers were assessed by staining techniques and qPCR analysis. In vivo activity was assessed in an ectopic bone formation model of athymic mice. Results: We demonstrate that Nell1 expression was up-regulated by BMP9. Exogenous Nell1 potentiated BMP9-induced late stage osteogenic differentiation while inhibiting the early osteogenic marker. Forced Nell1 expression enhanced BMP9-induced osteogenic regulators/markers and inhibited BMP9-upregulated expression of adipogenic regulators/markers in MSCs. In vivo ectopic bone formation assay showed that exogenous Nell1 expression enhanced mineralization and maturity of BMP9-induced bone formation, while inhibiting BMP9-induced adipogenesis. Conversely, silencing Nell1 expression in BMP9-stimulated MSCs led to forming immature chondroid-like matrix. Conclusion: Our findings indicate that Nell1 can be up-regulated by BMP9, which in turn accelerates and augments BMP9-induced osteogenesis. Exogenous Nell1 may be exploited to enhance BMP9-induced bone formation while overcoming BMP9-induced adipogenesis in regenerative medicine.

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The Use of Injectable Chitosan/Nanohydroxyapatite/Collagen Composites with Bone Marrow Mesenchymal Stem Cells to Promote Ectopic Bone Formation In Vivo

Journal of Nanomaterials ◽

10.1155/2013/506593 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 7

Author(s):

Bo Yu ◽

Yichen Zhang ◽

Xiaoming Li ◽

Qiongren Wang ◽

Yi Ouyang ◽

...

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Bone Formation ◽

Bone Structure ◽

Ectopic Bone Formation ◽

Ct Reconstruction ◽

Bone Mesenchymal Stem Cells ◽

Inflammatory Reactions ◽

Ectopic Bone

The aim of this study was to evaluate ectopic in vivo bone formation with or without rat bone mesenchymal stem cells (rBMSCs) of an injectable Chitosan/Nanohydroxyapatite/Collagen (CS/nHAC) composite. The CS/nHAC composites were injected subcutaneously into the backs of Wistar rats with freshly loaded rBMSCs at a density of10×106 cells/mL, and the CS/nHAC composites without cells were used as negative controls. New bone formation, degradation of composites, and degree of calcification were evaluated by Computed Tomography (CT) and three-dimensional (3D) CT reconstruction. Histological evaluations were performed to further assess bone structure and extracellular matrix by HE and Masson staining. The inflammatory reactions related to osteogenesis were also investigated in the present study. In comparison with the CS/nHAC composites, this study revealed that CS/nHAC/rBMSCs composites showed relatively higher percentage of calcification, better establishment of ECM, and less degradation rate. Meanwhile, different extents of inflammatory reactions were also observed in the CS/nHAC and CS/nHAC/rBMSCs explants at 2 and 4 weeks after implantation. Altogether, CS/nHAC/rBMSCs composites are superior to CS/nHAC composites in ectopic bone formation. In conclusion, the rBMSCs-seeded CS/nHAC composites may be beneficial to enhancing ectopic bone formation in vivo.

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