Dental Stem Cells and Tooth Banking for Regenerative Medicine

Stem cells (SCs) are undifferentiated cells capable of self-renewal and differentiation into multiple functional cell types. These cells are widely used in injury repair and tissue regeneration.1,2 Adult SCs have been isolated from a variety of tissues including bone marrow, brain, liver, lungs, breast, skin, skeletal muscles, hair follicles and teeth.3,4 Dental-derived SCs have been isolated and identified as the cell sources for tooth repair and regeneration. These cells are named according to their anatomical locations, and are characterized by their SC markers, colony-forming ability, and dental regenerative function. Current research indicates that dental SCs may have the potential to regenerate bone, the periodontal ligament (PDL), and possibly teeth. Thus, appropriate cryopreservation of these dental cells, tissues and teeth are imperative to realize the opportunities of these SCs for medical applications, particularly for autotransplantation.5 However, the optimal methods for tissue cryopreservation remain largely unknown. Masato et al described long-term tooth cryopreservation using a programmed freezer with a magnetic field, the socalled Cell Alive System (CAS).6 Using the CAS method, the PDL showed good cell viability and differentiation capability after cryopreservation.6 In support of this, further experiments by Temmerman et al demonstrated Stem cell (SC) therapy has a promising future for tissue regenerative medicine. However, because SC technology is still in its infancy, interdisciplinary cooperation is needed to achieve successful clinical applications. Dental SCs have drawn attention in recent years because of their accessibility, plasticity, and high proliferative ability. Several types of dental SCs have been identified, including dental pulp SCs from adult human dental pulp, SCs from human primary exfoliated deciduous teeth, periodontal ligament SCs, and dental follicle SCs from human third molars. Similar to mesenchymal SCs, these dental SCs can undergo self-renewal and have multipotent differentiation ability, but do not have the ethical issues associated with other sources of SCs. Therefore, appropriate preservation procedures for dental SCs and teeth are now needed. Here, we discuss the opportunities for tooth-banking (as it is now clinically feasible and commercially available), the advantages and limitations of current cryopreservation techniques for dental SCs/teeth or tissues, and the current status of tooth banks. Received: Sep 23, 2009 Revised: Mar 5, 2010 Accepted: Mar 12, 2010