Evaluation of implant-materials as cell carriers for dental stem cells under in vitro conditions.

Background: Dental stem cells in combination with implant materials may become an alternative to autologous bone transplants. For tissue engineering different types of soft and rigid implant materials are available, but little is known about the viability and the osteogenic differentiation of dental stem cells on these different types of materials. According to previous studies we proposed that rigid bone substitute materials are superior to soft materials for dental tissue engineering.

The AKT signaling pathway sustains the osteogenic differentiation in human dental follicle cells.

Signaling transduction pathways are established by interactions between growth factors, protein kinases, and transcription factors, and they play a crucial role in tooth development. Precursor cells of the dental follicle (DFCs) are used for in vitro studies about molecular mechanisms during periodontal development. Previous studies have already shown that the growth factor BMP2 and the transcription factor EGR1 are involved in the osteogenic differentiation in DFCs while interactions with protein kinase-based pathways remain elusive.

The WNT inhibitor APCDD1 sustains the expression of β-catenin during the osteogenic differentiation of human dental follicle cells.

In hair follicle cells APCDD1 inhibits the canonical WNT/β-Catenin pathway and its inactivation is associated with an autosomal dominant form of hair loss. We analyzed the role of APCDD1 for the osteogenic differentiation in dental follicle cells (DFCs) and identified a new and surprising function. Contrarily to hair follicle cells APCDD1 was crucial for the expression of β-Catenin and for the activity of the TCF/LEF reporter assay in DFCs.

A protein kinase A (PKA)/β-catenin pathway sustains the BMP2/DLX3-induced osteogenic differentiation in dental follicle cells (DFCs).

The directed expression of osteogenic transcription factors via a balanced activation of signaling pathways is an important prerequisite for the development of mineralized tissues. A positive-feedback loop of the BMP2-dependent SMAD signaling pathway and the DLX3 transcription factor (BMP2/DLX3 pathway) directs the osteogenic differentiation of periodontal precursor cells from the dental follicle (DFCs). However, little is known how this BMP2/DLX3 pathway interacts with other crucial signaling pathways such as the WNT/β-catenin signaling pathway.

AKT and MET signalling mediates antiapoptotic radioresistance in head neck cancer cell lines.

Objectives: Induction of apoptosis is a major mechanism of radiosensitivity in different types of cancer. In contrast, EGFR/PI3K/AKT signalling and recently the presence of so-called cancer stem cells are discussed as reasons for radioresistance.

Materials And Methods: The study investigates mechanisms of apoptosis, key oncogenes of the PI3K/AKT pathway and the presence of cancer cells with stem cell properties during irradiation in two cell lines (PCI-9A, and PCI-15) of head and neck squamous cell carcinoma.