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Item does not contain fulltext Periodontal ligament (PDL) cells are regarded as the cell type with the highest potential for periodontal regeneration. Biophysical cues of the culture substrate are increasingly identified as vital parameters to affect cell behavior. Compared to traditional tissue culture polystyrene (TCPS), polydimethylsiloxane (PDMS) substrates corroborate more closely the elastic modulus values of the physiological environment. Consequently, the aim of this study was to evaluate the effect of PDMS-based substrates with different stiffness on cellular responses of human PDL cells. PDMS substrates with different stiffness were fabricated by varying the ratio of base to curing component. The influence of PDMS substrates on PDL cell spreading and cytoskeletal morphologies, motility, proliferation, stemness gene expression, and osteogenic differentiation was evaluated and compared to that on conventional TCPS. PDL cells cultured on PDMS substrates exhibited a smaller cell size and more elongated morphology, with less spreading area, fewer focal adhesions, and faster migration than cells on TCPS. Compared to TCPS, PDMS substrates promoted the rapid in vitro expansion of PDL cells without interfering with their self-renewal ability. In contrast, the osteogenic differentiation ability of PDL cells cultured on PDMS was lower in comparison to cells on TCPS. PDL cells on PDMS exhibited similar cell morphology, motility, proliferation, and self-renewal gene expression. The stiffer PDMS substrate increased the osteogenic gene expression of PDL cells compared to the soft PDMS group in one donor. These data indicate that PDMS-based substrates have the potential for the efficient PDL cell expansion. 01 december 2019

Item does not contain fulltext AIM: The implantation of bone marrow-derived mesenchymal stem cells (MSCs) has previously been shown successful to achieve periodontal regeneration. However, the preferred pre-implantation differentiation strategy (e.g. maintenance of stemness, osteogenic or chondrogenic induction) to obtain optimal periodontal regeneration is still unknown. This in vivo study explored which differentiation approach is most suitable for periodontal regeneration. MATERIALS AND METHODS: Mesenchymal stem cells were obtained from Fischer rats and seeded onto poly(lactic-co-glycolic acid)/poly(varepsilon-caprolactone) electrospun scaffolds, and then pre-cultured under different in vitro conditions: (i) retention of multilineage differentiation potential; (ii) osteogenic differentiation approach; and (iii) chondrogenic differentiation approach. Subsequently, the cell-scaffold constructs were implanted into experimental periodontal defects of Fischer rats, with empty scaffolds as controls. After 6 weeks of implantation, histomorphometrical analyses were applied to evaluate the regenerated periodontal tissues. RESULTS: The chondrogenic differentiation approach showed regeneration of alveolar bone and ligament tissues. The retention of multilineage differentiation potential supported only ligament regeneration, while the osteogenic differentiation approach boosted alveolar bone regeneration. CONCLUSION: Chondrogenic differentiation of MSCs before implantation is a useful strategy for regeneration of alveolar bone and periodontal ligament, in the currently used rat model. 01 april 2015

Item does not contain fulltext Periodontitis is the most common human infectious disease. Regeneration of bone and soft tissue defects after periodontitis remains challenging, although the transplantation of periodontal ligament (PDL) cells seems a liable strategy. However, little is known about the function of PDL cells after transplantation. In the current study, a combination of in vitro coculture systems and in vivo immunohistochemistry (IHC) was used to investigate the role of PDL cells in the regenerative process. First, a coculture method was used, in which mesenchymal cells (representing the host tissue) were brought into direct contact with PDL cells (representing the transplanted cell population). It was found that PDL cells significantly increased mineralized matrix formation and osteocalcin expression, whereas control cells did not. Similar results were obtained when a noncontact coculture system was applied separating PDL and mesenchymal cells. In an in vivo rat model, regeneration of alveolar bone and ligament was seen after PDL cell transplantation. Implanted PDL cells were found clustered along the newly formed tissues. IHC showed enhanced osteopontin expression and gap junction staining in areas neighboring implanted PDL cells. In conclusion, PDL cells enhance periodontal regeneration through a trophic factor stimulating the osteogenic activity of the surrounding host cells.

The aim of this study is to optimize enzymatic control over gelation of chitosan-based hydrogels for the delivery of periodontal ligament cells (PDLCs). The results reveal that the gelation time, strength, and degradation rate of the chitosan hydrogels can be controlled precisely by variation of the urea and urease concentrations. PDLCs remain viable inside these hydrogels for up to 30 days. Cells released from the hydrogel upon degradation and collected after 3, 15, and 30 days are able to form colonies and osteogenically differentiate. In conclusion, the enzymatic control over the gelation of chitosan hydrogels offers options for the delivery of PDLCs.

Item does not contain fulltext The murine-derived MC3T3-E1 cell line provided by the American Type Culture Collection (ATCC) is a well-known osteogenic cell culture model system to test materials in vitro. However, the effect of passaging on its mineralization capacity has never been described and their culture supplements can be further optimized. Therefore, we evaluated the influence of the passage number and different osteogenic culture supplements, including ascorbic acid (AsAP) and dexamethasone (Dex) on the osteogenic capacity of MC3T3-E1 cells. This capacity was measured by the deposited calcium, the alkaline phosphatase activity, and the expression of osteogenic-related genes, including bone sialoprotein (BSP), osteocalcin (OC), and osteopontin (OPN). The results indicated that the mineralization capacity of MC3T3-E1 cells significantly decreased during passaging and got exhausted at passage 34, as assessed by measuring calcium deposition after 28 days of osteogenic induction. Moreover, the combination of AsAP and Dex triggered significantly more mineralization in MC3T3-E1 cells than the ATCC recommended addition of AsAP alone, as indicated by increased calcium deposition and higher expression of BSP and OPN. However, Dex alone could not trigger this effect, but only in combination with the AsAP, which indicates that Dex has no direct effect on mineralization. In conclusion, the passage number of MC3T3-E1 cells is of great importance and the use of cells above 30 passages should be avoided. In addition, the favored osteogenic supplements providing an improved osteogenic differentiation of MC3T3-E1 cells are the combination of AsAP and Dex.

The mathematical model of Two-Phase flow of water and gas in aquifer is established based on the Darcy linear percolation law and law of conservation of mass of fluid mechanics. According to the fully implicit difference method, time and spatial discretization of the model lead to a set of nonlinear equations, which can be transferred into a group of linear equations. The linear equations can be solved using the Jacobi-iteration pretreatment because of its high stability and fast convergence speed of the solution positively. The distribution of the saturation and formation pressure with time in the process of gas injection is analyzed by using the mathematical model. The results show that the gas saturation increases with the gas injection rate, the permeability and reservoir thickness increasing whereas the formation pressure increases slowly under same cumulative gas injection rate. The formation pressure increases at first and then decreases to reach a steady value.

Considering the various influencing factors of enrichment of coal bed methane, the evaluation indexes of enrichment for coal bed methane are determined. The weight values of all factors indexes are given and the fuzzy mathematics model is established on the basis of the fuzzy mathematics. As a case study, the fuzzy mathematics model is applied to the assessment of enrichment of coal bed methane. The results show that the No.5 coal seam of Shan 2 of Shanxi formation in Daning-Jixian is a better enrichment area. The evaluation result performed on the basis of the fuzzy mathematics model is in good agreement with the measured result. The example indicates that the method is credible and has high precise. The assessment system established in the paper can be regarded as a reference model in coal bed methane exploitation potential assessment.

Item does not contain fulltext This study is aimed to evaluate the in vivo biocompatibility and periodontal regenerative potential of enzymatically solidified chitosan hydrogels with or without incorporated periodontal ligament cells (PDLCs). To this end, chitosan hydrogels, with (n=8; CHIT+CELL) or without (n=8; CHIT) fluorescently labeled PDLCs, were prepared and transplanted into rat intrabony periodontal defects; untreated defects were used as empty controls (n=8; EMPTY). After 4 weeks, maxillae were harvested, decalcified, and used for histological, histomorphometrical, and immunohistochemical assessments. The results showed that PDLCs remained viable upon encapsulation within chitosan hydrogels before transplantation. Histological analysis demonstrated that the chitosan hydrogels were largely degraded after 4 weeks of implantation, without any adverse reaction in the surrounding tissue. In terms of periodontal regeneration, alveolar bone height, alveolar bone area, and epithelial downgrowth were comparable for CHIT, CHIT+CELL, as well as EMPTY groups. In contrast, both CHIT and CHIT+CELL showed a significant increase in functional ligament length compared with EMPTY. From a cellular perspective, the contribution of chitosan hydrogel-incorporated cells to the periodontal regeneration could not be ascertained, as no signal from transplanted PDLCs could be detected at 4 weeks posttransplantation. The results demonstrated that enzymatically solidified chitosan hydrogels are highly biocompatible and biodegradable. Moreover, chitosan hydrogels without cell loading can improve periodontal regeneration in terms of functional ligament length, indicating the great potential of this hydrogel in clinical applications. Further work on the use of chitosan hydrogels as cell carriers is required.

The quantity of regenerated bone induced by recombinant human bone morphogenetic protein-2 (rhBMP2) is encouraging, but sometimes the quality is inferior. Recombinant human beta-nerve growth factor (rh beta-NGF) plays a major role in bone remodeling. This study evaluates the quality and quantity of regenerated bone in periodontal regeneration following topical application of the two growth factors to Class III furcation defects.Thirty-six inflamed Class III furcation defects were created in six beagle dogs at sites of mandibular premolars 2, 3, and 4, and then biodegradable hydrogel incorporating rhBMP2 and rh beta-NGF was topically applied to the defects. The groupings were as follows: G1, untreated (control group A); G2, carrier alone (control group B); G3, 0.4% rhBMP2 + carrier; G4, 2% rh beta-NGF + carrier; G5, 0.4% rhBMP2 + 2% rh beta-NGF + carrier; and G6, 0.2% rhBMP2 + 1% rh beta-NGF + carrier. Eight weeks after application, the quality and quantity of regenerated tissue were evaluated by scanning electron microscopy observation, calcium/phosphorus ratio analysis, and histologic evaluation.The regenerated bone in G5 exhibited the highest calcium/phosphorus ratio among all groups and showed a denser structure with more calcified substances on the collagen fiber surface than that in the other groups. Histomorphometric analysis revealed that 0.4% rhBMP2 + 2% rh beta-NGF promoted the highest percentage of periodontal regeneration among all groups.The results of this pilot study suggest that a topical application of rhBMP2 and rh beta-NGF may improve the quality and quantity of regenerated bone in artificially created Class III furcation defects of beagle dogs.