ALL STEM CELLS

Subject

This study examines a silk fibroin/chitosan/nanohydroxyapatite (SF/CS/nHA) composite biomimetic scaffold combined with autologous concentrated growth factor (CGF). It focuses on promoting bone marrow mesenchymal stem cell (BMSC) proliferation and osteogenic differentiation, enhancing the repair of critical bone defects.

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Objectives and Overview

The research aims to address challenges in bone tissue engineering, such as low clinical translation efficiency, by developing a biomimetic scaffold with excellent biocompatibility. Combining SF/CS/nHA scaffolds with autologous CGF, the study evaluates their effectiveness in repairing critical-sized bone defects in vitro and in vivo.

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Key Findings and Clinical Implications

1. Material Composition and Preparation

• SF/CS/nHA Scaffold:
  
  
  
  • Silk fibroin (SF): Offers biocompatibility and structural stability.
  
  
  • Chitosan (CS): Provides biodegradability and compatibility with human tissue.
  
  
  • Nanohydroxyapatite (nHA): Mimics bone's mineral structure and enhances mechanical properties.
  
  
  
  


• Preparation Techniques:
  
  
  
  • Vacuum freeze-drying and cross-linking were used to create 3%, 4%, and 5% SF/CS/nHA scaffolds.
  
  
  • 4% scaffolds were optimal, with 83% porosity and a pore size of ~126 µm, suitable for cell adhesion and nutrient exchange.
  
  
  
  

2. Role of Concentrated Growth Factor (CGF)

• CGF is an advanced platelet concentrate containing BMP-2, VEGF, and other growth factors.


• It forms a fibrin network that supports angiogenesis and osteogenesis.


• CGF enhances the slow and stable release of growth factors, mimicking physiological processes.

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In Vitro Experiments

• BMSC Proliferation and Morphology:
  
  
  
  • CGF improved BMSC proliferation and cell morphology, increasing cell adhesion and extension on the scaffold.
  
  
  • Live/dead staining confirmed scaffold biocompatibility, with minimal cytotoxicity.
  
  
  
  


• Osteogenic Differentiation:
  
  
  
  • Enhanced alkaline phosphatase (ALP) activity and mineralization, as observed with alizarin red staining.
  
  
  • Upregulated osteogenic markers (Runx-2, Col-1, OCN) in the CGF-scaffold group.
  
  
  
  

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In Vivo Experiments

• Rabbit Radius Bone Defect Model:
  
  
  
  • Critical bone defects were treated with SF/CS/nHA scaffolds combined with CGF.
  
  
  • Radiological assessments (3D CT) showed significant bone defect healing in the CGF-scaffold group.
  
  
  • Histological analysis revealed organized bone trabeculae and neovascularization.
  
  
  
  


• Results:
  
  
  
  • Superior bone regeneration in the CGF-scaffold group compared to scaffolds or BMSCs alone.
  
  
  • High expression of Col-1 and CD31 indicated effective bone matrix formation and angiogenesis.
  
  
  
  

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Conclusion and Clinical Potential

1. Efficacy:
   
   
   
   • The SF/CS/nHA scaffold combined with CGF significantly promotes bone repair, highlighting its dual role in osteogenesis and vascularization.
   
   
   
   


2. Biocompatibility:
   
   
   
   • The scaffold and CGF exhibit minimal toxicity and excellent compatibility.
   
   
   
   


3. Clinical Translation:
   
   
   
   • The biomimetic approach offers a promising solution for treating critical bone defects, with potential for application in regenerative therapies.
   
   
   
   

This study presents a robust strategy for bone tissue engineering, emphasizing the synergy between biomimetic scaffolds and autologous growth factors.