Figure 2. Growth curves and change in differentiation potential of hDPSCs during long-term culture. (A) Curves for long-term growth obtained from 11 cell lines isolated from individuals of various stages (crown-completed stage, DP1, 2, 11, 28, and 31 [red]; root-formative stage, DP27 [black]; root-completed stage, DP29, 33, 34, 54, and 75 [black]). Cells isolated from the crown-completed stage maintained a high growth rate for more than 2 mos, whereas those from later stages showed a lower growth rate. (B) ALP staining of crown-completed stage (DP1 [top]) and root-formative stage (DP27 [bottom]) cell cultures at P3, 10, 20, and 30, respectively. DP1 and DP27 cells lost their differentiation capability induced by confluence after long-term culture. (C) In vivo differentiation of crown-completed stage (DP1) cells at P4 and P10. Transplants were removed at 8 wks post-transplantation, sectioned, and stained with hematoxylin and eosin. High-magnification view of the boxed area in the left photo is shown in the middle one. In P4 transplants, the scaffolds (Sc) were lined with a layer of dentin-like matrix (d, middle) surrounding connective tissue (CT) and an interface layer of odontoblast-like cells (od, middle); whereas no dentin-like matrix was observed in P10 transplants. Scale bar = 200 µm (left and right), 100 µm (middle).