Figure 1.

Late MSCs impede proliferation and osteogenic differentiation of early MSCs. (A) Early and late MSCs were seeded in each well of 6-well plates at indicated cell numbers (early:late, in left upper site) and cultured for 14 days. Cells were then stained with crystal violet and the colony number for each well is shown in right upper site. Representative data for three independent experiments are shown. (B) A total of 100 early MSCs were cultured in the absence or presence of indicated number of late MSCs in 6-well plates and cultured for 14 days. The cells were stained with crystal violet. (C) A total of 100 early MSCs were cultured in the absence or presence of 100 late MSCs in 6-well plates and cultured for 14 days. The cells were stained with crystal violet (upper) and the colony number for each well is shown in right upper site. The dye was extracted for OD measurement at 570 nm (lower). Bar = 10 mm. (D) A total of 100 early MSCs were cultured in the absence or presence of 100 late MSCs in 6-well plates and cultured for 7 days, and replaced with osteogenic induction media for an additional 14 days. The cells were stained with Alizarin Red-S (upper) and the dye was extracted for OD measurement at 550 nm (lower). Bar = 10 mm (upper); 200 μm (lower). Data are expressed as mean ± SD. (n = 3). Asterisks indicate significant differences as determined by the unpaired Student’s t-test (** p < 0.01 versus early MSCs).