Cell sheet engineering and its application for periodontal regeneration.

Periodontitis is a inflammation induced by a bacterial infection that causes the destruction of the attachment apparatus of dental roots. Several materials, such as bone graft materials, barrier membranes and protein products have been developed and used to treat periodontal defects clinically; however, it is difficult to regenerate the complete periodontal tissue structure. Recently, cytotherapeutic approaches have been introduced to overcome the limitation of conventional procedures. The in vitro-expanded autologous cells derived from several kinds of tissues have already been used in several clinical trials. These cytotherapeutic treatments have been shown to be safe and effective for the treatment of periodontitis. Our strategy has been to integrate stem cell biology and cell sheet engineering, in which a temperature-responsive intelligent polymer is grafted onto the surface of cell culture dish to create a 'cell sheet', to achieve a novel treatment method for periodontitis. By simple reduction of the temperature to below 32°C, a contiguous cell sheet, which is capable of keeping extracellular matrix proteins and cell-cell interactions intact, can be harvested for transplantation without the use of scaffolds. This technology has already been employed in clinical trials, confirming the safety and efficacy of the treatment. In this review, we introduce recent progress in the engineering of cell sheets and review the potential of cell sheet technology for periodontal regenerative medicine.