Gradient multi-walled carbon nanotubes-based scaffold for cartilage tissue engineering

Introduction. Novel treatment methods of articular cartilage injuries are challenging for scientists. Nowadays, joint degenerative changes resulting from articular cartilage defects are the most common disorder of the... [ view full abstract ]

Introduction. Novel treatment methods of articular cartilage injuries are challenging for scientists. Nowadays, joint degenerative changes resulting from articular cartilage defects are the most common disorder of the musculoskeletal system. Osteoarthritis is now the third most common cause of disability in the world's population. Currently the research has focused on the introduction of new surgical techniques and more advanced biomaterials. Recent investigations include modifications of biocompatible scaffolds, formed by crosslinking of natural and synthetic fibers (hybridization). The ideal scaffold should restore, maintain or improve tissue function, which is the main goal of therapy. In the treatment of articular cartilage defects the scaffold should allow the proliferation of cartilage cells in the site of injury, while preserving the unique properties of chondrocytes. The repaired tissue, in the three-dimensional (3D) form, could therefore more easily integrate with the surrounding cartilage.
Methods. The aim of our project was to develop innovative, gradient scaffold for cartilage reconstruction based on multi-walled carbon nanotubes (MWCNTs). In our project, we have created a carbon scaffold for cartilage cell (chondrocytes) growth, composed of three different densities of nanotubes. The physico-chemical and biomechanical features of the biomaterial have been characterized using scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectroscopy. Next, we investigated the cell growth and expansion on different MWCNTs constructs.
Results. Results showed that chondrocytes proliferation was the most effective on the most dense nanotube surface. Moreover, chondrocytes adhered well to the MWCNTs surface and were evenly distributed. The cells were growing separately and displayed multiple cytoplasmic extensions (filopodia). The cell extensions were responsible for bending the nanotubes, resulting in the formation of a 3D structure. The interaction between cell extensions and carbon nanotubes led to the alteration of cell morphology and the direction of their growth. Moreover no toxic effect of MWCNTs towards chondrocytes was observed. Discussion. Most previous studies indicated good properties of carbon fibers as cell carriers. Our study confirmed that the MWCNT-based constructs stimulate and support the growth of articular cartilage cells and therefore are suitable to restore the multi-layered structure of the tissue.