RESUMO
<p><b>OBJECTIVE</b>To evaluate the effect of aging on the proliferative and differentiation capacity of human periodontal ligament stem cells (PDLSCs).</p><p><b>METHODS</b>Human periodontal ligament tissues were obtained from surgically extracted third molars from 6 subjects aged 18-20 years (group A) and 6 subjects aged 45-50 years (group B). The proliferative capacity of PDLSCs isolated from the tissues was examined with MTT assay, and the osteogenic and adipogenic differentiation capacity of the cells were evaluated using alizarin red staining and oil red O staining. SA-βG expression was analyzed to assess the cell senescence. In both groups, PDLSCs were induced for osteogenic differentiation for 7 days, and the differentiation ability of the cells was assessed by examining alkaline phosphatase (ALP) activity and by detecting the expressions of osteocalcin (OCN) and ALP using Western blotting.</p><p><b>RESULTS</b>Human PDLSCs were successfully isolated from the 12 teeth and were characterized as MSCs. The PDLSCs derived from donors of different ages were all capable of osteogenic and adipogenic differentiation, but their proliferative and osteogenic differentiation capacity decreased with the donors' age. The cells also exhibited an age- related increase in adipogenic differentiation capacity and SA-βG expression. In both groups, the cells induced in osteogenic medium showed increased OCN expression and ALP activation, and the increments were more obvious in group A.</p><p><b>CONCLUSION</b>Human PDLSCs can be isolated from periodontal ligament tissues even from donors of advanced ages, but their proliferative and differentiation capacity decreases and their adipogenic differentiation capacity increases with age.</p>
RESUMO
<p><b>OBJECTIVE</b>To compare the osteogenic differentiation potential and osteoclast capacity between stem cells from human exfoliated deciduous teeth (SHED) in the physiological root resorption period and dental pulp stem cells (DPSCs).</p><p><b>METHODS</b>SHED and DPSCs were isolated, purified and cultured in vitro. The two stem cells were examined with ALP staining at 14 days and with alizarin red staining at 21 days of osteogenic induction, and the expressions of the genes associated with osteogenesis and osteoclastogenesis were detected using real-time PCR.</p><p><b>RESULTS</b>The isolated SHED and DPSCs both showed an elongate spindle-shaped morphology. After osteogenic induction of the cells, Alizarin red staining visualized a greater number of mineralized nodules in SHED than in DPSCs (P<0.05), and SHED also exhibited a stronger ALP activity than DPSCs (P<0.05). RT-PCR test results showed that the two stem cells expressed RANKL,OCN, ALP, OPG and Runx2 mRNA after osteogenic induction, but the expression levels of Runx2, OCN and ALP were lower in DPSCs than in SHED (P<0.05), and the ratio of RANKL/OPG was significantly higher in SHED (P<0.05).</p><p><b>CONCLUSIONS</b>Compared with DPSCs, SHED has not only the ability of osteogenic differentiation but also an osteoclast capacity, which sheds light on the regulatory role of SHED in physiological root resorption bone remodeling.</p>