Lipid-free fibroblast-like cells, known as dedifferentiated fat (DFAT) cells, can be generated from mature adipocytes with a large single lipid droplet. DFAT cells can re-establish their active proliferation ability and can transdifferentiate into various cell types under appropriate culture conditions. The first objective of this study was to compare the multilineage differentiation potential of DFAT cells with that of adipose-derived stem cells (ASCs) on mesenchymal stem cells. We obtained DFAT cells and ASCs from inbred rats and found that rat DFAT cells possess higher osteogenic differentiation potential than rat ASCs. On the other hand, DFAT cells show similar adipogenic differentiation, and chondrogenic differentiation potential in comparison with ASCs. The second objective of this study was to assess the regenerative potential of DFAT cells combined with novel solid scaffolds composed of PLGA (Poly d, l-lactic-co-glycolic acid) on periodontal tissue, and to compare this with the regenerative potential of ASCs combined with PLGA scaffolds. Cultured DFAT cells and ASCs were seeded onto PLGA scaffolds (DFAT/PLGA and ASCs/PLGA) and transplanted into periodontal fenestration defects in rat mandible. Micro computed tomography analysis revealed a significantly higher amount of bone regeneration in the DFAT/PLGA group compared with that of ASCs/PLGA and PLGA-alone groups at 2, 3, and 5 weeks after transplantation. Similarly, histomorphometric analysis showed that DFAT/PLGA groups had significantly greater width of cementum, periodontal ligament and alveolar bone than ASCs/PLGA and PLGA-alone groups. In addition, transplanted fluorescent-labeled DFAT cells were observed in the periodontal ligament beside the newly formed bone and cementum. These findings suggest that DFAT cells have a greater potential for enhancing periodontal tissue regeneration than ASCs. Therefore, DFAT cells are a promising cell source for periodontium regeneration.

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Dedifferentiated fat (DFAT) cells derived from mature adipocytes have mesenchymal stem cells' (MSCs) characteristics. Generally, mature adipocytes are 60-110 μm in diameter; however, association between adipocyte size and dedifferentiation efficiency is still unknown. This study, therefore, investigated the dedifferentiation efficiency of adipocytes based on cell diameter. Buccal fat pad was harvested from five human donors and dissociated by collagenase digestion. After exclusion of unwanted stromal cells by centrifugation, floating adipocytes were collected and their size distribution was analyzed. The floating adipocytes were then separated into two groups depending on cell size using 40- and 100-μm nylon mesh filters: cell diameters less than 40 μm (small adipocytes: S-adipocytes) and cell diameters of 40-100 μm (large adipocytes: L-adipocytes). Finally, we evaluated the efficiency of adipocyte dedifferentiation and then characterized the resultant DFAT cells. The S-adipocytes showed a higher capacity to dedifferentiate into DFAT cells (S-DFAT cells) compared to the L-adipocytes (L-DFAT cells). The S-DFAT cells also showed a relatively higher proportion of CD146-positive cells than L-DFAT cells, and exhibited more osteogenic differentiation ability based on the alkaline phosphatase activity and amount of calcium deposition. These results suggested that the S- and L-DFAT cells had distinct characteristics, and that the higher dedifferentiation potential of S-adipocytes compared to L-adipocytes gives the former group an advantage in yielding DFAT cells.

We previously generated induced pluripotent stem (iPS) cells from human dental pulp cells of deciduous teeth. Neural crest cells (NCCs) play a vital role in the development of the oral and maxillofacial region. Therefore, NCCs represent a cell source for bone, cartilage, and tooth-related tissue engineering. In this study, we examined whether iPS cells are capable of differentiating into NCCs through modification of the human embryonic stem cell protocol. First, iPS cells were dissociated into single cells and then reaggregated in low-cell-adhesion plates with neural induction medium for 8 days in suspension culture to form neurospheres. The neurospheres were transferred to fibronectin-coated dishes and formed rosette structures. The migrated cells from the rosettes abundantly expressed NCC markers, as evidenced by real-time polymerase chain reaction, immunofluorescence, and flow cytometric analysis. Furthermore, the migrated cells exhibited the ability to differentiate into neural crest lineage cells in vitro. They also exhibited tissue-forming potential in vivo, differentiating into bone and cartilage. Collectively, the migrated cells had similar characteristics to those of NCCs. These results suggest that human dental pulp cell-derived iPS cells are capable of differentiating into NCCs. Therefore, iPS cell-derived NCCs represent cell sources for bone and cartilage tissue engineering.