Effects of Multiwalled Carbon Nanotube Reinforced Collagen Scaffolds on the Osteogenic Differentiation of Mesenchymal Stem Cells

With recent advances in nanotechnology, carbon nanotubes (CNTs) have been extensively studied as substrates for cell culture, drug delivery systems, and medical implant materials. However, surprisingly little is known about the effect of CNTs on collective cellular processes (e.g., adhesion, proliferation, and differentiation). This leads to the need for quantitative characterization of the proliferation, differentiation, and mineralization of mesenchymal stem cells (MSCs) on multiwalled CNT-s (MWCNTs-) collagen scaffolds. In here, a set of MWCNTs-collagen scaffolds where three different types of MWCNTs are, respectively, entrapped in reconstituted type I collagen at four different concentrations less than 100 ppm are prepared; the MSC differentiation thereon is investigated by monitoring the transcription factor RunX2 (RunX), transforming growth factor β (TGF-β), alkaline phosphatase (AP), osteocalcin, and mineralized nodules of extracellular matrix (ECM). In short, the MWCNT-collagen scaffolds induced significant increases in AP activity and ECM mineralization due to the increased stiffness and strength of the scaffold by entrapping MWCNTs. This offers a potential for controlling MSC differentiation using MWCNT-collagen scaffolds. 1. Background There have been significant advances in cell-based therapy and tissue engineering for the repair and replacement of damaged tissues and organs. Now, scientific investigations in this area have been keeping observation upon nanotechnology that has great potential in creating next-generation approaches. More recently, researches have begun to focus on the role of nanostructures and nanomaterials for tissue engineering applications [1]. For example, CNTs introduced by Oberlin et al. in 1976 [2] have been regarded as promising substrates for cell-based therapy and tissue engineering (e.g., cell cultures, drug delivery systems, medical implantable materials, etc.) because of their unique material properties [3–9]. Although nanomaterial-based scaffolds (e.g., CNTs) are believed to provide many critical features of the microenvironments for cell adhesion, proliferation, and differentiation [1], much still remains uncertain and controversial about the effect of the nanomaterial-based scaffolds on the collective cellular processes. The recent advent of nanotechnology has stimulated an interest in creating a variety of new nanotechnology-based approaches for creating improved scaffolds with engineered tissues. The first pioneering research using composites of synthetic polymers and CNTs has demonstrated great promise