We conclude that blocking Notch signalling with DAPT enhances adipogenesis of differentiated mASCs at an early stage. It may be due to depression of DLK-1/Pref-1 and promotion of de-PPAR-gamma activation, which work through inhibition of Notch-2-Hes-1 pathway by DAPT.

Mesenchymal stem cells (MSCs) provide us an excellent cellular model to uncover the molecular mechanisms underlying adipogenic differentiation of adult stem cells. PPARγ had been considered as an important molecular marker of cells undergoing adipogenic differentiation. Here, we demonstrated that expression and phosphorylation of PPARγ could be found in bone marrow–derived MSCs cultured in expansion medium without any adipogenic additives (dexamethasone, IBMX, insulin or indomethacin). Then, PPARγ was dephosphorylated in MSCs during the process of adipogenic differentiation. We then found that inhibition of MEK activation by specific inhibitor (PD98059) counteracted the PPARγ expression and phosphorylation. However, expression and phosphorylation of PPARγ did not present in MSCs cultured in medium with lower serum concentration. When these MSCs differentiated into adipocytes, no phosphorylation could be detected to accompany the expression of PPARγ. Moreover, exposure of MSCs to higher concentration of serum induced stronger PPARγ expression, and subsequently enhanced their adipogenesis. These data suggested that activation of the MEK/ERK signalling pathway by high serum concentration promoted PPARγ expression and phosphorylation, and subsequently enhanced adipogenic differentiation of MSCs.

Background A 1‐2 mm thick labial plate is generally advocated in immediate implant placement and provisionalization (IIPP). However, most of the human labial plates fail to meet this requirement. Purpose This study aimed to investigate the effect of labial plate thickness on hard tissue, soft tissue, and esthetic outcomes in IIPP. Materials and Methods In this prospective cohort study, 40 patients received IIPP of 50 single‐crown implants in the anterior maxilla. Patients were categorized into three groups according to their presurgical thickness of labial bone: 0‐0.5, 0.5‐1, and ≥ 1 mm. CBCT, mucosa recession and the papilla index were used to analyze labial hard and soft tissue alterations with a 1‐year follow‐up. Results At 1 year, OCI bone losses were 1.17 ± 0.73, 0.37 ± 0.39, 0.46 ± 0.35 mm; ICH bone losses were 2.23 ± 1.83, 0.74 ± 0.71, 0.72 ± 1.27 mm; TM recessions were 1.00 ± 0.51, −0.06 ± 0.37, −0.30 ± 0.88 mm; TL recessions were 0.61 ± 1.02, −0.18 ± 0.40, −0.26 ± 1.15 mm; TD recessions were 0.61 ± 1.02, −0.18 ± 0.40, −0.26 ± 1.15 mm; PIS scores were 1.63 ± 0.64, 2.20 ± 0.71, 2.71 ± 0.57 in group 0‐0.5, 0.5‐1 and ≥ 1 mm, respectively. No statistical significance was found between group 0.5‐1 and ≥ 1 mm in bone resorption, gingival recession, and papilla index. The bone resorption and gingival recession were significantly the highest in group 0‐0.5 mm at 6 months and 1 year. Conclusions Group 0.5‐1 mm had similar tissue dimensional alteration as group ≥1 mm, while group <0.5 mm suffered more massive bone resorption and gingival recession. Concerning the thickness of the labial plate, this study may suggest an expansion in the indication of IIPP.

IntroductionMechanical forces play critical roles in the development and remodelling process of bone. As an alternative cell source for bone engineering, adipose-derived stem cells (ASCs) should be fully investigated for their responses to mechanical stress and the mechanisms responsible for osteogenic induction in response to mechanical signals.Material and methodsWe hypothesized that appropriate application of uniaxial cyclic tensile strain to ASCs could increase bone morphogenetic protein-2 (BMP-2) expression and improve osteogenesis of ASCs. To test our hypothesis, ASCs from the same flask of the same donor were subjected to tensile strain with different patterns in order to eliminate the difference of donor site and passage. After surface markers investigation, the osteo-induced ASCs were subjected to uniaxial cyclic tensile stretch with the following two loading patterns: long duration continuous pattern (6 h, 1 HZ, 2000 µɛ) and short duration consecutive pattern (17 min every day for 10 consecutive days, 1 HZ, 2000 µɛ). Then osteogenic related genes were analysed by real-time PCR.ResultsThe ASCs were positive for the markers STRO-1, CD90 and CD44 and negative for CD34. Cyclic tensile strain of 6 continuous h’ duration significantly increased gene expressions of BMP-2 and Runx2, and depressed OCN mRNA expression. In contrast, mechanical loading of 17 min every day did not significantly affect gene expression of BMP-2, Runx2, OCN or ALP.ConclusionsWe indicate that ASCs may sense mechanical loading in a duration-dependent manner and cyclic tensile stretch may modulate the osteogenic differentiation of ASCs via the BMP-2 signalling pathway.

A reciprocal relationships between osteogenesis and adipogenesis has been observed in vitro and in vivo, and mechanical stretch has been believed to be a regulating factor of osteo-adipogenic axis differentiation of mesenchymal stem cells. In this study, rat adipose stem cells (ASCs) were isolated and cultured in adipogenic or normal medium. Their exposure to cyclic mechanical stretch (2000 με, 1 Hz) in the presence of adipogenic medium decreased mRNA and protein level of PPAR-γ, and increased Runx2 mRNA and protein levels as well as Pref-1 mRNA level, compared to static samples. ASCs cultured in normal medium without adipogenic induction did not show any significant change in mRNA expression of PPAR-γ, Runx2, nor Pref-1 irrespective of mechanical loading. Stretching induced phosphorylation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) during the induction period. It was concluded that mechanical stretch inhibited adipogenesis and stimulated osteogenesis of these ASCs in the presence of adipogenic medium and that ERK1/2 activation may be involved in the mechanical stress-induced trans-differentiation.