The promotion of bone regeneration by nanofibrous hydroxyapatite/chitosan scaffolds by effects on integrin-BMP/Smad signaling pathway in BMSCs

Biomaterials. 2013 Jun;34(18):4404-17. doi: 10.1016/j.biomaterials.2013.02.048. Epub 2013 Mar 17.


In bone tissue engineering, a combination of biomimetic nanofibrous scaffolds with renewable stem cells has recently emerged as a new strategy for promoting bone regeneration. We have previously developed a biomimetic nanocomposite nanofibrous scaffold of hydroxyapatite/chitosan (nHAp/CTS) [1]. However, the mechanism behind the supportive function of the scaffolds has not yet been adequately explored. Here, we evaluated the effect of nHAp/CTS seeded with bone marrow mesenchymal stem cells (BMSCs) on bone regeneration and examined the underlying mechanism in vitro and in vivo. The scaffolds of nHAp/CTS induced higher proliferation of BMSCs than membranous hydroxyapatite/chitosan (mHAp/CTS) and electrospun nanofibrous chitosan (nCTS) did. Interestingly, regardless the nanfibrous effect, nHAp/CTS and mHAp/CTS supported the spindle-shaped morphology, in contrast to the spherical shape of BMSCs on nCTS, indicating that HAp supports cell adhesion. Furthermore, the levels of the mRNA for Smad1, BMP-2/4, Runx2, ALP, collagen I, integrin subunits together with myosins were significantly up-regulated on nHAp/CTS whereas these genes were expressed at markedly low levels on mHAp/CTS and nCTS even in osteogenic medium. In addition, the critical proteins pSmad1/5/8 in BMP pathway showed clear nuclear localization and osteocalcin were significantly elevated on nHAp/CTS than mHAp/CTS (P < 0.01) and nCTS (P < 0.01). Similarly, the cells exhibited higher ALP activity on nHAp/CTS than mHAp/CTS (P < 0.01) and nCTS (P < 0.05). Therefore, the findings indicated the activating of intergrin-BMP/Smad signaling pathway of BMSCs on nHAp/CTS. Finally, in vivo, nHAp/CTS/BMSCs had a superior ability of bone reconstruction than other groups for cranial bone defects. In conclusion, our results demonstrated that nHAp/CTS scaffold promotes bone regeneration by supporting the adhesion, proliferation and activating integrin-BMP/Smad signaling pathway of BMSCs both in vitro and in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaline Phosphatase / metabolism
  • Animals
  • Bone Marrow Cells / cytology
  • Bone Marrow Cells / drug effects
  • Bone Marrow Cells / ultrastructure
  • Bone Morphogenetic Proteins / genetics
  • Bone Morphogenetic Proteins / metabolism
  • Bone Regeneration / drug effects*
  • Bone Regeneration / genetics
  • Cell Proliferation / drug effects
  • Cell Separation
  • Cell Shape / drug effects
  • Chitosan / pharmacology*
  • Durapatite / pharmacology*
  • Extracellular Matrix / drug effects
  • Extracellular Matrix / genetics
  • Female
  • Gene Expression Regulation / drug effects
  • Implants, Experimental
  • Integrins / genetics
  • Integrins / metabolism
  • Membranes, Artificial
  • Mesenchymal Stem Cells / cytology
  • Mesenchymal Stem Cells / drug effects
  • Mesenchymal Stem Cells / metabolism*
  • Mesenchymal Stem Cells / ultrastructure
  • Nanofibers / chemistry*
  • Nanofibers / ultrastructure
  • Osteocalcin / metabolism
  • Osteogenesis / drug effects
  • Osteogenesis / genetics
  • Radiography
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction / drug effects*
  • Signal Transduction / genetics
  • Skull / diagnostic imaging
  • Skull / pathology
  • Smad Proteins / genetics
  • Smad Proteins / metabolism
  • Tissue Scaffolds / chemistry*


  • Bone Morphogenetic Proteins
  • Integrins
  • Membranes, Artificial
  • Smad Proteins
  • Osteocalcin
  • Chitosan
  • Durapatite
  • Alkaline Phosphatase