Apoptosis Of Dental Pulp Stem Cells Research Articles

Stage-Dependent Regulation of Dental Pulp Stem Cell Odontogenic Differentiation by Transforming Growth Factor-β1.

Transforming growth factor-β1 (TGF-β1) is an important multifunctional cytokine with dual effects on stem cell differentiation. However, the role of TGF-β1 on odontogenic differentiation of dental pulp stem cells (DPSCs) remains to be entirely elucidated. In the present study, we initially investigated the effect of TGF-β1 at a range of concentrations (0.1-5 ng/mL) on the proliferation, cell cycle, and apoptosis of DPSCs. Subsequently, to determine the effect of TGF-β1 on odontogenic differentiation, alkaline phosphatase (ALP) activity and Alizarin Red S (ARS) staining assays at different concentrations and time points were performed. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis were used to determine the levels of odonto-/osteo-genic differentiation-related gene and protein expression, respectively. For in vivo studies, newly formed tissue was assessed by Masson's trichrome and von Kossa staining. Data indicated that TGF-β1 inhibited DPSCs proliferation in a concentration-and time-dependent manner (p < 0.05) and induced cell cycle arrest but did not affect apoptosis. ALP activity was enhanced, while ARS reduced gradually with increasing TGF-β1 concentrations, accompanied by increased expression of early marker genes of odonto-/osteo-genic differentiation and decreased expression of late-stage mineralization marker genes (p < 0.05). ALP expression was elevated in the TGF-β1-treatment group until 14 days, and the intensity of ARS staining was attenuated at days 14 and 21 (p < 0.05). Compared with the control group, abundant collagen but no mineralized tissues were observed in the TGF-β1-treatment group in vivo. Overall, these findings indicate that TGF-β1 promotes odontogenic differentiation of DPSCs at early-stage while inhibiting later-stage mineralization processes.

Osteogenic stimulation of human dental pulp stem cells with self-setting biphasic calcium phosphate cement.

Calcium phosphate cement (CPC) is widely used as a repair material for bone defects. However, there is no report on the use of biphasic CPC combined with dental pulp stem cells (DPSCs) for bone tissue engineering. The aim of this study was to construct biphasic CPC and to investigate its effect in the osteogenic stimulation of human DPSCs (hDPSCs) and macrophage polarization. Biphasic CPC was developed by adding different ratios of β-TCP to an equimolar mixture of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA). The biocompatibility, osteogenic capacity, and inflammatory reactions of the cements were examined. Our results show that biphasic CPC containing both HA and β-TCP was successfully fabricated. The addition of β-TCP did not increase necrosis or apoptosis of DPSCs. Significant increases in hDPSC mineral deposition and osteogenic marker (ColI and ALP) expression were observed in 20% TCP-CPC. The addition of β-TCP did not promote macrophage polarization to a proinflammatory phenotype. In conclusion, biphasic CPC with hDPSCs for bone regeneration was developed for the first time; the biphasic CPC combined with hDPSCs is expected to be used for the repair and regeneration of bone.

The putative role of insulin-like growth factor (IGF)-binding protein 5 independent of IGF in the maintenance of pulpal homeostasis in mice.

Although insulin-like growth factor binding protein 5 (IGFBP5) may play a crucial role in activating the functions of periodontal and bone marrow stem cells, the factors responsible for regulating the maintenance of dental pulp stem cells (DPSCs) remain to be clarified. This study aimed to elucidate the role of IGFBP5 in maintaining pulpal homeostasis during tooth development and pulpal healing after tooth injury in doxycycline-inducible TetOP-histone 2B (H2B)-green fluorescent protein (GFP) transgenic mice (GFP expression was induced at E14.5 or E15.5) by using TUNEL assay, RT-PCR, in situ hybridization for Igfbp5, and immunohistochemistry for IGFBP5, Nestin, and GFP. To observe the pulpal response to exogenous stimuli, the roots of the maxillary first molars were resected, and the coronal portion was autografted into the sublingual region. Intense IGFBP5/Igfbp5 expression was observed in cells from the center of the pulp tissue and the subodontoblastic layer in developing teeth during postnatal Week 4. Intense H2B-GFP-expressing label-retaining cells (LRCs) were localized in the subodontoblastic layer in addition to the center of the pulp tissue, suggesting that slowly dividing cell populations reside in these areas. During postoperative days 3–7, the LRCs were maintained in the dental pulp, showed an IGFBP5-positve reaction in their nuclei, and lacked a TUNEL-positive reaction. In situ hybridization and RT-PCR analyses confirmed the expression of Igfbp5 in the dental pulp. These findings suggest that IGFBP5 play a pivotal role in regulating the survival and apoptosis of DPSCs during both tooth development and pulpal healing following tooth injury.

Effects of adrenomedullin on proliferation and differentiation of dental pulp stem cells

Objective To explore the effects of adrenomedullin( ADM) on the proliferation and odontogenic differentiation potential of dental pulp stem cells( DPSCs). Methods The 3rdgeneration of cultured human DPSCs were treated with ADM of different concentrations( 10- 6mol / L,10- 7mol / L and 10- 8mol / L) for 24 h,and a blank control group was also set up. Cell apoptosis and cell cycle were measured by flow cytometry; the mRNA and protein expressions of alkaline phosphatase( ALP),an odontogenic differentiation marker,were analyzed by qPCR and Western blotting analysis,respectively. Results Cell cycle analysis showed that the proportion of G2/ S / M phase cells in the three ADM treatment groups were significantly higher than that in the blank control group( P 0. 05),but there were no significant differences between the three ADM groups. Cell apoptosis analysis showed that the proportion of cells labelled by Annexin Ⅴ+/ PI-was significantly lower in the three ADM groups than that in the blank control group( P 0. 05), but there were no signficant differences between the three ADM groups. The results of qPCR and Western blotting analysis showed that the ALP expression in DPSCs was increased significantly compared with that in the blank control group( P 0. 01),but there were no significant differences between the three ADM groups. Conclusion ADM can promote the proliferation and inhibit the apoptosis of DPSCs,and it can also promote odontogenic differentiation of DPSCs.