Functionalized Graphene Nanoparticles Induce Human Mesenchymal Stem Cells to Express Distinct Extracellular Matrix Proteins Mediating Osteogenesis.
Purpose
The extracellular matrix (ECM) labyrinthine network secreted by mesenchymal stem cells (MSCs) provides a microenvironment that enhances cell adherence, proliferation, viability, and differentiation. The potential of graphene-based nanomaterials to mimic a tissue-specific ECM has been recognized in designing bone tissue engineering scaffolds. In this study, we investigated the expression of specific ECM proteins when human fat-derived adult MSCs adhered and underwent osteogenic differentiation in the presence of functionalized graphene nanoparticles.


Methods
Graphene nanoparticles with 6-10% oxygen content were prepared and characterized by XPS, FTIR, AFM and Raman spectroscopy. Calcein-am and crystal violet staining were performed to evaluate viability and proliferation of human fat-derived MSCs on graphene nanoparticles. Alizarin red staining and quantitation were used to determine the effect of graphene nanoparticles on osteogenic differentiation. Finally, immunofluorescence assays were used to investigate the expression of ECM proteins during cell adhesion and osteogenic differentiation.


Results
Our data show that in the presence of graphene, MSCs express specific integrin heterodimers and exhibit a distinct pattern of the corresponding bone-specific ECM proteins, primarily fibronectin, collagen I and vitronectin. Furthermore, MSCs undergo osteogenic differentiation spontaneously without any chemical induction, suggesting that the physicochemical properties of graphene nanoparticles might trigger the expression of bone-specific ECM.


Conclusion
Understanding the cell-graphene interactions resulting in an osteogenic niche for MSCs will significantly improve the application of graphene nanoparticles in bone repair and regeneration.
['Newby|Steven D|SD|', 'Masi|Tom|T|', 'Griffin|Christopher D|CD|', 'King|William J|WJ|', 'Chipman|Anna|A|', 'Stephenson|Stacy|S|', 'Anderson|David E|DE|0000-0003-0745-7591', 'Biris|Alexandru S|AS|', 'Bourdo|Shawn E|SE|0000-0002-9302-2094', 'Dhar|Madhu|M|0000-0002-0610-5351']
D002454:Cell Differentiation D002478:Cells, Cultured D016326:Extracellular Matrix Proteins D006108:Graphite D006801:Humans D016023:Integrins D059630:Mesenchymal Stem Cells D053758:Nanoparticles D010012:Osteogenesis D010100:Oxygen D056951:Photoelectron Spectroscopy D055503:Protein Multimerization
functionalized graphene graphene nanoparticles human mesenchymal stem cells extracellular matrix fibronectin collagen I osteogenic niche