Introduction: Teeth are complex organs containing two separate mineral and hard tissues. Loosing teeth is not life threatening but it is important in clinic and appearance. Today, new therapies are being used in modern dentistry, but they are not completely successful. To overcome these problems, new approaches are being developed to use stem cells and tissue engineering in order to repair and regenerate teeth. Teeth contain different stem cells with epithelial and mesenchymal origins. In this review we will discuss dental mesenchymal stem cells. Dental pulp stem cells (DPSCs): DPSCs are isolated from human dental pulp. These adherent cells share same characters with BM-MSCs and exhibit high proliferation and colony formation. They are multipotent and express MSCs markers like CD146 and STRO-1. DPSCs can differentiate into odontoblastic, adipogenic and osteoblastic cell types. In vivo transplantation into immune compromised mice demonstrated the ability of DPSCs to generate dentine/pulp-like complex. They could also differentiate into active neurons and showed potential for cell therapy of neuronal disorders. Stem cells from human exfoliated deciduous teeth (SHEDs): SHEDs are isolated from pulp of human exfoliated deciduous teeth. They show high proliferation, colony formation and differentiation capacity into odontoblasts, adipoctyes and neurons. Compared with DPSCs, SHEDs exhibit higher proliferation rate, ability to form spherical aggregates and can also generate bone in vivo and they are not capable of generating dentine/pulp-like structure. It has been shown that transplantation of SHED spheres into the striatum of parkinsonian rats partially improved the apomorphine evoked rotation of behavioral disorders. These data suggested that SHEDs can be considered as a source of stem cells in alleviating Parkinson\\\\\\\'s disease. Periodontal ligament stem cells (PDLSCs): Periodontal tissue plays the main role in maintaining teeth and contains stem cells that show differentiation ability into cementoblasts, adipocytes and fibroblasts. Like BM-MSCs, PDLSCs are CD146 and STRO-1 positive and can form cementum/PDL-like structures, when they are transplanted into immune compromised mice. Root apical papilla stem cells (SCAPs): Dental papilla which has not developed completely, contains MSCs that can differentiate into odontoblast-like cells. These cells are called SCAPs. They also have the potential to differentiate into adipocytes and neurons. Compared to DPSCs, SCAPs exhibit high proliferation capacity. By cotransplanting SCAPs and PDLSCs into tooth sockets of mini pigs, dentine and periodontal ligament were formed. These data showed that SCAPs, along with PDLSCs, can generate biological root. Concluding remarks: Despite all the progress, there are still lots of obstacles to use stem cells in teeth regeneration and repair. Teeth are a viable source of adult mesenchymal stem cells for a wide range of clinical applications. Dental pulp cells grow well in culture and, interestingly, the proportion of cells with stem cell properties appears to increase with passage.

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