FIG. 1.

Light and transmission electron microscopy of primary cultures of human periodontal ligament stem cells (hPDLSCs) at the second passage in xeno-free medium. (A, B) Light microscopy of semithin section at different magnification. The cells show mainly a spindle-shaped appearance with long cytoplasmatic processes; some polygonal cells are present. Bars respectively: 100 μm, 10 μm. (C, D) Transmission electron microscopy of thin sections. (C) Cells with euchromatic nuclei (N) show a large cytoplasm containing numerous mitochondria (M), rough endoplasmic reticulum (RER) profiles, and residual lysosomal bodies (L). Bar: 2 μm. (D) Contact zones between cells (arrow) are shown at high magnification. Bar: 0.2 μm. (E) Trypan blue exclusion test shows the proliferation rate and viability of hPDLSCs maintained in culture with MSCGM (standard conditions) and MSCGM-CD (xeno-free medium). An increase in cell growth, time dependent, is evident in xeno-free culture. The y-axis shows cell number, and x-axis shows culture time. The data represent the mean of three separate experiments with five different cell lines. (F) Proliferation rate is assessed by MTT assay in five hPDLSCs grown with xeno-free medium and MSCGM. The proliferation rate is measured as the absorbance detected at 650 nm OD. Results are expressed as mean and standard deviation of three independent experiments, in which five different samples are used (***P<0.001). (G) A representative karyotyping of hPDLSCs primary culture appears completely normal. Color images available online at www.liebertpub.com/tec