Numbers of vital cells were evaluated after days 1, 2, 3, and 6. For cell counting, cell cultures were incubated with the cell counting kit 8 (CCK8) ready to use solution according to manufactures instructions (Dojindo, Rockville, MD, USA). The optical density (O.D.) was measured at a wavelength of 450 nm. For the evaluation of the cell adherence (normalized to standard cell culture dishes), cell proliferation (normalized to cell number at day 1 of cell culture) relative cell numbers were calculated.

The induction of apoptosis in DFCs and dNC-PCs was evaluated by measuring the Cell Event® Caspase3/7 Green Flow cytometry assay (Life Technologies, Carlsbad, CA, USA). For the Caspase3/7assay, cells were cultivated in eluates as described above. After 24 h, cells were harvested by trypsin-EDTA treatment, washed with PBS, and stained first with Caspase3/7 Green Detection Reagent (25 min, 37°C). After this step 1-mM SYTOX® AADvanced dead cell stain solution was added to the sample (5 min, 37°C). Cell fluorescence was analyzed at 488-nm excitation and applied to standard fluorescence compensation. Emission of fluorescence was measured with 530/30 BP (Caspase3/7 Green Detection Reagent) and with 690/50 BP (SYTOX® AADvanced dead cell stain) filters. Cells positive for Caspase3/7 Green Detection Reagent were identified as apoptotic cells, while dead cells were positive for SYTOX® AADvanced dead cell stain. However, vital cells were negatively stained for both staining solutions.

For protein isolation, cells were treated with lysis buffer (250 μl phosphatase, 100 mM Na3VO4, 137 mM NaCl, 200 mM Tris, 480 mM NaF, 1% NP-40, 10% Glycerol) on ice for 2 min. A protease-inhibitor (1 Protease Inhibitor Cocktail tablet from Roche) was included to minimize protein degradation. Cell lysates were placed on ice for 10 min. Protein samples were separated by SDS-polyacrylamide gel electrophoresis in pre-casted 12% Tris-glycine gels (Invitrogen, Waltham, MA, USA) and blotted to nitrocellulose membranes. Membranes were blocked with skimmed milk for 1 h and incubated with primary antibodies that were specific for proteins BAX (pro apoptotic protein), BCL2 (anti apoptotic protein), and β-Actin (housekeeper protein). Washed membranes were then incubated with a horseradish peroxidase-labeled secondary antibody. The detection of the secondary antibody was performed via chemiluminescence and X-ray films (GE Healthcare, Pewaukee, WI, USA).