Magnetic nanoparticles for improving cell invasion in tissue engineering.

It has been widely recognized that cells are seeded onto only the superficial layer of three-dimensional (3D) scaffolds in tissue engineering technology. This leads to tissue necrosis that occurs in the central part of 3D scaffolds. To solve this issue, an effective cell seeding technique into the central part of 3D scaffolds is required. Chitosan has characteristics of biocompatibility, biodegradability, and low-toxicity. In this study, we developed novel magnetic nanoparticles (MNs) coated with chitosan for enhancing cellular invasion using magnetic force. Cell-invasion efficiency was enhanced by introducing our novel MNs into cells and by the presence of magnetic force. This invasion efficacy depends on the degree of magnetic force. Matrix metalloproteinases and adhesion molecules that were upregulated in response to the attached nanoparticles and exposure to a magnetic force may also play a crucial role in improving cell-invasive ability in this system. This current system can efficiently enhance cell seeding into the depth of the scaffold, increase subsequent cell-cell interactions and shorten the period of cell proliferation. This system is thought to be useful in the development of cell-based strategies for the repair or replacement of tissue and other novel therapies.