Publications by authors named "Joachim Volk"

Development of clinical-grade, cell preparations is central to cGMP (good manufacturing practice compliant) conditions. This study aimed to investigate the potential of two serum/xeno-free, cGMP (StemPro, StemMacs) culture media to maintain "stemness" of human minor salivary gland stem cell (mSG-SC) cultures compared to a complete culture medium (CCM). Overall, StemMacs resulted in higher proliferation rates after p.

View Article and Find Full Text PDF

Objectives: Peri-implantitis (PI) is an inflammatory disease associated with peri-implant bone loss and impaired healing potential. There is limited evidence about the presence of mesenchymal stromal cells (MSCs) and their regenerative properties within the granulation tissue (GT) of infrabony peri-implantitis defects. The aim of the present study was to characterize the cells derived from the GT of infrabony PI lesions (peri-implantitis derived mesenchymal stromal cells-PIMSCs).

View Article and Find Full Text PDF

Objective: The angiogenic differentiation of dental pulp stem cells (DPSCs) is important for tissue homeostasis and wound healing. In this study the influence of 2-hydroxyethyl methacrylate (HEMA) on angiogenic differentiation was investigated.

Methods: To evaluate HEMA effects on angiogenic differentiation, DPSCs were cultivated in angiogenic differentiation medium (ADM) in the presence or absence of non-toxic HEMA concentrations (0.

View Article and Find Full Text PDF

Objective: Objective of our investigation was to determine the influence of CQ on the expression of antioxidant proteins and extracellular proteases in a 3D co-culture model (3DCCM) of the oral mucosa and to analyze the distribution and stability of CQ within 3D-CCMs.

Methods: 3D-CCMs consist of confluent keratinocytes (OKF6/TERT2) on cell culture inserts on top of human gingival fibroblasts (HGFs) in collagen. The treatment was carried out by adding CQ to the cell culture inserts at two time points with declining concentrations.

View Article and Find Full Text PDF

Objective: 2-Hydroxyethyl methacrylate (HEMA) is a component of many resin-modified materials and elutes from dental restorations into the oral cavity. Objective of our investigation was to determine the impact of HEMA on oral keratinocytes (OKF6/TERT2) and gingival fibroblasts (HGFs) in a newly established 3D co-culture model (3D-CCM) and to analyze the permeability of OKF6/TERT2 cells for HEMA.

Methods: Well-characterized 3D-CCMs, consisting of confluent OKF6/TERT2 cells on cell culture inserts above HGF-containing collagen gels, were treated supra-epithelial with HEMA.

View Article and Find Full Text PDF

Objectives: 2-Hydroxyethyl methacrylate (HEMA) is a widely used monomer of dental resin composite materials. Incomplete curing of resins leads to elution of HEMA, which may come in contact with different cells in oral tissues. We aimed to analyze the impact of HEMA on the transcription of genes participating in detoxification of oxidative stress, inflammatory response and organization of the extracellular matrix (ECM) using human gingival fibroblasts (HGFs) and human oral keratinocytes (OKF6/TERT2).

View Article and Find Full Text PDF

Objective: Dental pulp stem cells (DPSCs) can differentiate into tissue specific lineages to support dental pulp regeneration after injuries. Triethylene glycol dimethacrylate (TEGDMA) is a widely used co-monomer in restorative dentistry with adverse effects on cellular metabolism. Aim of this study was to analyze the impact of TEGDMA on the angiogenic differentiation potential of DPSCs.

View Article and Find Full Text PDF

Objectives: Phenylbis(acyl) phosphine oxide (BAPO) and diphenyl(acyl) phosphine oxide (TPO) are alternative photoinitiators to camphorquinone (CQ) in dental resinous materials. Aim of this study was to investigate their cytotoxic/genotoxic potential in human oral keratinocytes (OKF6/Tert2) and Chinese hamster lung fibroblasts (V79) in comparison to CQ.

Methods: Cells were exposed to different concentrations of BAPO and TPO (1-50μM).

View Article and Find Full Text PDF

Background: Development of clinical-grade cell preparations is central to meeting the regulatory requirements for cellular therapies under good manufacturing practice-compliant (cGMP) conditions. Since addition of animal serum in culture media may compromise safe and efficient expansion of mesenchymal stem cells (MSCs) for clinical use, this study aimed to investigate the potential of two serum/xeno-free, cGMP culture systems to maintain long-term "stemness" of oral MSCs (dental pulp stem cells (DPSCs) and alveolar bone marrow MSCs (aBMMSCs)), compared to conventional serum-based expansion.

Methods: DPSC and aBMMSC cultures (n = 6/cell type) were established from pulp and alveolar osseous biopsies respectively.

View Article and Find Full Text PDF

Introduction: The dietary pigment curcumin is a natural polyphenol extracted from the Curcuma longa rhizomes native to South Asia. The antioxidative, antimicrobial, and anti-inflammatory activities besides its unknown side effects suggest that curcumin could be a promising antiresorptive agent to prevent replacement resorption in replanted teeth after traumatic avulsion. Piperine, an alkaloid present in black pepper, seems to enhance the bioavailability and activity of curcumin.

View Article and Find Full Text PDF

Objective: Released components of oral biomaterials can leach into the oral cavity and may subsequently reach the gastrointestinal tract. Camphorquinone (CQ) is the most common used photoinitiator in resinous restorative materials and is often combined with the co-initiator N,N-dimethyl-p-toluidine (DMT). It has been shown that CQ exerts cytotoxic effects, at least partially due to the generation of reactive oxygen species (ROS).

View Article and Find Full Text PDF

Objectives: Aim of this study was to investigate whether Dental Pulp Stem Cells-DPSCs responses to pulp injury caused by resinous monomers is be mediated through activation of Wnt/β-catenin signaling.

Methods: DPSCs cultures were established from third molars of healthy donors and characterized for stem cell markers with flow cytometry. Cells were exposed to TEGDMA (T: 0.

View Article and Find Full Text PDF

Introduction: Root resorption is a common complication after replantation following traumatic dental avulsion. Endodontic therapy combined with local and intracanal medications aims to avoid osteoclastic activity. In such cases, the application of alendronate (ALN), a bisphosphonate widely used for the treatment of bone disorders, could be of clinical relevance.

View Article and Find Full Text PDF

Objectives: The photoinitiator camphorquinone (CQ), used in dental restorative materials, was found to be cytotoxic in cell cultures. Previously, we have shown that CQ induces alkali labile sites and DNA strand breaks in human gingival fibroblasts (HGF) associated with an increase of intracellular reactive oxygen species (ROS). Therefore, the objective of our study was to evaluate if DNA damage in HGF cells is caused by the generation of ROS.

View Article and Find Full Text PDF

Objectives: Camphorquinone (CQ) is a widely used photoinitiator in dental visible light (VL)-cured resinous materials. However, little is known about the toxicity of CQ in human cells. This study was designed to investigate CQ induced oxidative strain and apoptosis in cultured human oral keratinocytes (OKF6/TERT 2).

View Article and Find Full Text PDF

Objective: The aim of this study was to investigate the effects of resinous monomers on the odontogenic differentiation and mineralization potential of apical papilla stem cells (SCAP).

Methods: Cultures were established from developing third molars of healthy donors aged 14-18 years-old and were extensively characterized for proliferation rate, colony forming unit efficiency and expression of stem cell markers (STRO-1, CD146, CD34, CD45, CD105, CD117-c-Kit, CD24, CD90, Nanog, Oct3/4), in order to select those with enhanced stem cell and odontogenic differentiation properties. SCAP enriched cultures were then induced for odontogenic differentiation in the continuous presence of low concentrations (0.

View Article and Find Full Text PDF

Objective: To evaluate whether the reduction/prevention of triethylene glycol dimethacrylate (TEGDMA)-induced decrease of intracellular glutathione (GSH) protects human periodontal ligament fibroblasts (HPLF) against cell death.

Methods: HPLF were preincubated for 30 min with exogenous GSH and then treated with TEGDMA (2.5 mM) with/without GSH (0.

View Article and Find Full Text PDF

Triethylene-glycol dimethacrylate (TEGDMA) is an important matrix comonomer used in many resin-modified dental materials. As the monomer-polymer conversion of these biomaterials is up to 80% at best, TEGDMA may leach into the oral cavity and the pulp in millimolar concentrations. Objective of this study was to evaluate whether TEGDMA is genotoxic in immortalized human oral keratinocytes (OKF6/TERT2), for example, due to formation of oxidative DNA-lesions.

View Article and Find Full Text PDF

Objectives: The aim of this study was to investigate the effects of HEMA and TEGDMA on the odontogenic differentiation potential of dental pulp stem/progenitor cells.

Methods: Dental stem/progenitor cell cultures were established from pulp biopsies of human deciduous teeth of 1-3 year-old children (Deciduous Teeth Stem Cells-DTSCs). Cultures were characterized for stem cell markers, including STRO-1, CD146, CD34, CD45 using flow cytometry.

View Article and Find Full Text PDF

Human deciduous teeth have been proposed as a promising source of mesenchymal stem cells for application in bone and dental tissue engineering. We established cultures of mesenchymal stem cells from the pulp of human deciduous teeth (deciduous teeth stem cells, DTSCs) and analyzed their morphologic, growth, immunophenotypic, and osteo/odontogenic differentiation characteristics using different isolation methods and culturing environments. We compared the biologic behavior of DTSCs isolated either by enzymatic dissociation (DTSCs-ED) or by direct outgrowth from pulp tissue explants (DTSCs-OG).

View Article and Find Full Text PDF

Objectives: Camphorquinone (CQ) is cytotoxic in cell cultures. The mechanism of this toxic action, however, is not yet clearly understood. Aim of this investigation was to analyze the effects of non-irradiated CQ on intracellular formation of reactive oxygen species (ROS), intracellular glutathione (GSH) content, and the integrity of DNA in cultured primary human gingival fibroblasts (HGF).

View Article and Find Full Text PDF

Objectives: Only few data are available about cytotoxic effects of leachable dental resin compounds in combination with hydrogen peroxide (H(2)O(2)) segregated from dental bleaching agents. Therefore, the purpose of this study was to evaluate the effects of various concentrations of triethylene-glycol dimethacrylate (TEGDMA) and H(2)O(2) on intracellular glutathione levels (GSH) and viability of human gingival fibroblasts (HGF) that are primary target cells of cytotoxic actions of these substances.

Methods: HGF were grown in 96-well plates for 24h, treated with various concentrations of TEGDMA (0.

View Article and Find Full Text PDF

Aim of this study was to investigate the effects of the resin monomer BisGMA on the glutathione concentration (monobromobimane assay) and apoptosis (Annexin V/PI-assay) of cultured primary human gingival fibroblasts. Cells were treated for up to 24h with 0.001-0.

View Article and Find Full Text PDF