| Summary: | 碩士 === 臺北醫學大學 === 牙醫學系碩博士班 === 98 === Background & Objectives: Recently, scientists have successfully cryopreserved the periodontal ligament with a special magnetic cryopreservation method, which could induce vitrification to avoid the injuries from ice crystals to the cells. Consequently, the healthy teeth extracted for orthodontic treatment or prevention of infection could be potential donor teeth for future auto-transplantation. With the advancement of stem cell technology, human dental pulp stem cells have been cultured and could be used in regenerative medicine. This study was aiming to expand the application of Tooth Bank from cryopreservation for auto-transplantation to long-term storage of dental pulp stem cells.
Materials & Methods: The teeth stored in Tooth Bank were designed as the programming cryopreserved group. The non-cryopreserved group was teeth on contralateral side of the same patient. Besides, there was a traditionally freezing group (cryopreserved with -20 ℃ traditional freezer instead of program freezer with magnetic field used in the programming cryopreserved group). Dental pulp stem cells were isolated with enzyme digestion method from these 3 groups. First, the successful rate of culturing dental pulp stem cells in these 3 groups would be evaluated (by the standard set in non-cryopreserved group). Furthermore, the growth curve (by MTT method), morphology (by scanning electronic microscope, SEM), surface markers of stem cells (by immunostaining of CD44 and STRO-1) and ability of differentiation (adipogenic and osteogenic differentiation) of the dental pulp stem cells in the programming cryopreserved group and the non-cryopreserved group were evaluated and compared.
Results: The dental pulp stem cells in 73 % of the teeth in the programming cryopreserved group were considered as not been influenced after cryopreservation, since they could be normally cultured. However, the dental pulp stem cells in only 20 % of the teeth in the traditionally freezing group could be normally cultured. The growth curves evaluated by MTT method had no statistical differences between programming cryopreserved and non-cryopreserved groups. The morphology observed from SEM showed similar variety of cells in both groups. Both of dental pulp stem cells isolated from the programming cryopreserved group and the non-cryopreserved groups showed positive surface markers of stem cells (CD44+ and STRO-1+) and ability of adipogenic and osteogenic differentiation.
Conclusion: The results of this study indicated that dental pulp stem cells would remain their growth potential, surface markers and multi-lineage differentiation ability even after magnetic programming cryopreservation of the whole teeth. Patients who store teeth in Tooth Bank will have teeth not only for auto-transplantation but also have the chance of later isolation of dental pulp stem cells in the future needs.
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