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Enkele minder bekende morfologische eigenschappen en detail-structuren van het Proximale Interphalangeale (PIP-) gewricht van de normale vinger worden besproken, die een rol zouden kunnen spelen bij de pathogenese van reumatoïde artritis. Naast het verloop van de capillairen in het gewrichtskapsel, en het gekruiste, laagsgewijze verloop van de vezelbundels in het proprius collateraal ligament (PCL) van het PIP-gewricht, spreken vooral de intra-articulaire plicae synoviales (synovial folds), en de in het PCL aanwezige gelamelleerde proprioceptieve lichaampjes tot de verbeelding. Ideeën worden geopperd omtrent mogelijke microtraumata van deze structuren. Recente literatuurgegevens suggereren namelijk het pathogenetisch belang van zulke microtraumata, die ook aanleiding kunnen zijn tot chronische gewrichtsontstekingen zoals reumatoïde artritis waarvan de (vroege) symptomen immers vaak de hand betreffen, met name de PIP-gewrichten.

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Introduction: L-PRF promotes tissue healing in clinical applications such as dental surgery. However, little is known about the mechanisms of action. Angiogenesis is a key process in tissue regeneration. Growth factors, fibrin and leukocytes, as present in L-PRF, are known to be important in angiogenesis. The goal of this study was to investigate whether L-PRF induces blood vessel formation. Materials and methods: The angiogenic cytokine profile of L-PRF CM and exudate was determined by an antibody array. The effect of L-PRF, and the involvement of CXCR2, on HUVEC viability, migration and tube formation was examined in vitro. Surface expression of CXCR2 on HUVEC was verified by flow cytometry. The ability of L-PRF to induce blood vessel formation in ovo was assessed. Results: An upregulation of pro-angiogenic factors that bind to CXCR2 was observed in CM. L-PRF was able to enhance in vitro HUVEC viability, migration and tube formation, although the CXCR2 antagonist SB225002 did not attenuate these effects. Flow cytometry showed that a small percentage of HUVEC expresses CXCR2. The pro-angiogenic effect of L-PRF was confirmed in the CAM assay. Conclusion: L-PRF exerts pro-angiogenic effects in vitro and in ovo. CXCR2 was not found as a main mediator of this enhancement. A better insight in the mechanisms of action of L-PRF is required to better understand its clinical effects and its potential as a strategy for therapeutic angiogenesis.

Therapeutic angiogenesis is very promising, however, current revascularization strategies are unsuccessful. Since angiogenesis is key to the development of the tooth, this study compared the angiogenic potential of 3 dental stem cell (DSC) types: dental pulp stem cells (DPSCs), dental follicle stem cells (FSCs) and stem cells from the apical papilla (SCAPs). Angiogenic factors secreted by the DSCs were identified in a Human Angiogenesis Array, followed by validation by means of ELISA and RT-PCR. In vitro assays with a Human Microvascular Endothelial Cell line (HMEC-1) were performed to gain more insights in the effect of the DSCs on HMEC-1 proliferation, migration and tube formation in an MTT assay, a transwell system and a Matrigel assay respectively. The various DSCs express pro- and anti-angiogenic factors and induce HMEC-1 migration and tube formation, but not proliferation. DSCs thus provide opportunities to treat patients with cells from their own or other individuals' teeth.

Stem cells are an ideal cell source to use in tissue engineering as they are able to differentiate into multiple cell lineages and tissues. Besides cells, a scaffold and blood vessels are required in this promising technique for treating the loss or failure of tissues or organs. The scaffold provides a three-dimensional support desirable for the adhesion, proliferation, migration and differentiation of the responding cells. In this study, titanium scaffolds will be used as they are biocompatible, have a high strength to weight ratio and are highly corrosion resistant. Blood vessels are necessary for the delivery of oxygen, nutrients and inductive signals to the implanted cells. These blood vessels can be formed by means of angiogenesis. Stem cells can promote this by either differentiating into endothelial cells or by excreting pro-angiogenic factors. In this study, three different dental stem cell (DSC) populations are explored and compared to investigate their angiogenic properties

The goal of this study is to elucidate the angiogenic properties and the endothelial differentiation potential of human dental pulp stem cells (hDPSC). Analysis of the angiogenic secretion profile indicated that hDPSC secrete a whole array of angiogenic factors. In vitro models showed a significant impact of hDPSC on the migration of endothelial cells, but not on proliferation or survival. With regard to the endothelial differentiation potential, flow cytometry indicated no expression of endothelial markers. Ultrastructural analysis showed no straightforward results but minor morphological changes were suggestive of an endothelial differentiation potential. Optimization of protocols is required to further determine the angiogenic properties of hDPSC. If hDPSC are able to contribute to vascular networks, this will have great therapeutic potential, not only in terms of pulp regeneration but also as a cell-based therapy for ischemic diseases.

Dental pulp stem cells (DPSC), mesenchymal stem cells (MSC) from the tooth, share phenotypical and multilineage characteristics with bone marrow derived MSCs (BMMSCs). Since DPSCs are much easier to harvest in comparison to BMMSCs they are considered as a useful alternative MSC source in stem cell research. As MSCs retain some plasticity, the neural differentiation potential of DPSCs will be evaluated. DPSCs will be labelled with the commercially available ferumoxide Endorem® to allow visualization with MRI following engraftment. This study shows expression of NeuN in neurogenic differentiated DPSCs. Future studies should include quantitative and electrophysiological experiments. This study also shows that the optimal concentration for labelling DPSCs is 0,75µg/ml PLL with 15µg/ml Endorem®. The influence of Endorem® labelling on cellular processes of DPSCs needs to be determined before these cells can be considered as a clinical applicable intracellular contrast agent for MRI analysi