Cell-based bone regeneration for alveolar ridge augmentation--cell source, endogenous cell recruitment and immunomodulatory function.

Alveolar ridge plays a pivotal role in supporting dental prosthesis particularly in edentulous and semi-dentulous patients. However the alveolar ridge undergoes atrophic change after tooth loss. The vertical and horizontal volume of the alveolar ridge restricts the design of dental prosthesis; thus, maintaining sufficient alveolar ridge volume is vital for successful oral rehabilitation. Recent progress in regenerative approaches has conferred marked benefits in prosthetic dentistry, enabling regeneration of the atrophic alveolar ridge. In order to achieve successful alveolar ridge augmentation, sufficient numbers of osteogenic cells are necessary; therefore, autologous osteoprogenitor cells are isolated, expanded in vitro, and transplanted to the specific anatomical site where the bone is required. Recent studies have gradually elucidated that transplanted osteoprogenitor cells are not only a source of bone forming osteoblasts, they appear to play multiple roles, such as recruitment of endogenous osteoprogenitor cells and immunomodulatory function, at the forefront of bone regeneration. This review focuses on the current consensus of cell-based bone augmentation therapies with emphasis on cell sources, transplanted cell survival, endogenous stem cell recruitment and immunomodulatory function of transplanted osteoprogenitor cells. Furthermore, if we were able to control the mobilization of endogenous osteoprogenitor cells, large-scale surgery may no longer be necessary. Such treatment strategy may open a new era of safer and more effective alveolar ridge augmentation treatment options.