Objective of this study is the novel application of Fourier transform infrared (FTIR) microscopic imaging to identify the differentiation state of individual human mesenchymal stem cells with or without osteogenic stimulation. IR spectra of several hundred single cells with lateral resolution of 5-10 microm were recorded using a FTIR imaging spectrometer coupled to a microscope with a focal plane array detector. A classification model based on linear discriminant analysis was trained to distinguish four cell types by their IR spectroscopic fingerprint. Without stimulation two cell types dominated, showing low or high levels of glycogen accumulation at the cell periphery. After stimulation, the protein composition in the cells changed and some cells started expressing calcium phosphate salts such as octacalciumphosphate, a precursor of the bone constituent hydroxyapatite. Few cells were identified which remained in their non-stimulated state. This study demonstrated for the first time that FTIR microscopic imaging can probe stem cell differentiation at the single cell level rapidly, non-destructively and with minimal preparation.

The aim of this study was to develop and test models for training dental students in periodontal examinations using manikins that had distinct anatomical designs but were indistinguishable in external appearance. After four models were tested for inter-and intra-examiner reliability by two experienced dentists, 26 additional models were produced. The models were tested by 35 dental students at a dental school in Germany in 2014. The testing involved completing a periodontal examination that included probing depths, gingival recessions, and furcation involvements. The primary purpose of the study was to determine whether the models could be used as a tool for periodontal examination training by the students. Levels of agreement (students and dentists) and Kappa statistics (dentists) were calculated using absolute (±0 mm) and tolerable difference (±1 mm). Over the span of two weeks, the dentists' reliability with preset values for probing depths, gingival recessions, and furcation involvements ranged from 0.29 to 0.38, 0.52 to 0.61, and 0.54 to 0.57, respectively, under absolute difference and from 0.86 to 0.90, 0.96 to 0.99, and 0.62 to 0.73, respectively, under tolerable difference. The students' proportions of agreement for probing depths and gingival recessions under absolute vs. tolerable difference were 34.8% vs. 79.9% and 71.9% vs. 94.4%, respectively. The students frequently scored values higher than the preset values, overestimated furcation involvements, and failed to differentiate the levels of furcations. The models used did not pose any systematic or technical difficulties in the pilot study. Students were unable to measure furcation involvements with acceptable agreement. Thus, these models could be used for student periodontal examination training.

Current strategies for tissue engineering of bone rely on the implantation of scaffolds, colonized with human mesenchymal stem cells (hMSC), into a recipient. A major limitation is the lack of blood vessels. One approach to enhance the scaffold vascularisation is to supply the scaffolds with endothelial cells (EC).The main goal of this study was to establish a coculture system of hMSC and EC for the purposes of bone tissue engineering. Therefore, the cell behaviour, proliferation and differentiation capacity in various cell culture media as well as cell interactions in the cocultures were evaluated.The differentiation capacity of hMSC along osteogenic, chondrogenic, and adipogenic lineage was impaired in EC medium while in a mixed EC and hMSC media, hMSC maintained osteogenic differentiation. In order to identify and trace EC in the cocultures, EC were transduced with eGFP. Using time-lapse imaging, we observed that hMSC and EC actively migrated towards cells of their own type and formed separate clusters in long term cocultures. The scarcity of hMSC and EC contacts in the cocultures suggest the influence of growth factor-mediated cell interactions and points to the necessity of further optimization of the coculture conditions.

BackgroundTissue engineering approaches for reconstruction of large bone defects are still technically immature, especially in regard to sufficient blood supply. Therefore, the aim of the present study was to investigate the influence of osteogenic stimulation and treatment with VEGF on new bone formation and neovascularization in hMSC-loaded cancellous bone scaffolds in vivo.MethodsCubic scaffolds were seeded with hMSC and either cultured in stem cell medium or osteogenic stimulation medium. One osteogenically stimulated group was additionally treated with 0.8 μg VEGF prior to subcutaneous implantation in athymic mice. After 2 and 12 weeks in vivo, constructs and selected organs were harvested for histological and molecular analysis.ResultsHistological analysis revealed similar vascularization of the constructs with and without VEGF treatment and absence of new bone formation in any group. Human DNA was detected in all inoculated scaffolds, but a significant decrease in cells was observed after 2 weeks with no further decrease after 12 weeks in vivo.ConclusionUnder the chosen conditions, osteogenic stimulation and treatment with VEGF does not have any influence on the new bone formation and neovascularization in hMSC-seeded cancellous bone scaffolds.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-350) contains supplementary material, which is available to authorized users.

BackgroundAmelogenin is an extracellular matrix protein well known for its role in the organization and mineralization of enamel. Clinically, it is used for periodontal regeneration and, due to its finding also in predentin and intercellular spaces of dental pulp cells, it has recently been suggested for pulp capping procedures. The aim of this study was to analyse in vitro the effect of the recombinant human full-length amelogenin on the growth and differentiation of human dental pulp stem cells (hDPSCs).MethodsHuman DPSCs were treated with a supplement of amelogenin at a concentration of 10 ng/ml, 100 ng/ml and 1000 ng/ml. The groups were compared to the unstimulated control in terms of cell morphology and proliferation, mineralization and gene expression for ALP (alkaline phosphatase), DMP1 (dentin matrix protein-1) and DSPP (dentin sialophosphoprotein).ResultsAmelogenin affects hDPSCs differently than PDL (periodontal ligament) cells and other cell lines. The proliferation rate at two weeks is significantly reduced in presence of the highest concentration of amelogenin as compared to the unstimulated control. hDPSCs treated with low concentrations present a downregulation of DMP1 and DSPP, which is significant for DSPP (p = 0.011), but not for DMP1 (p = 0.395).ConclusionsThese finding suggest that the role of full-length amelogenin is not restricted to participation in tooth structure. It influences the differentiation of hDPSC according to various concentrations and this might impair the clinical results of pulp capping.