Results 30 Cell area and aspect ratio were manually evaluated on basis of phase contrast images over the complete culture period. The aspect ratio describes the perpendicular ratio of the maximum diameter (Ferrets diameter) and the minimum diameter. These parameters were assessed for the same quarters of cell culture time as defined before. The results of 100 cells per quarter are presented in figure 14. There were less FC cells in the first quarter of both culture conditions, while the majority of the cells had a RS or SS like morphology (Fig. 14A). Within the second quarter, progressively FC cells emerged inside the normoxic group, albeit hypoxic cultured cells kept their small appearance (Fig. 14B). Values for cell area and aspect ratio are given in table 4. Fig. 14: Quantification of cell area and aspect ratio of normoxic and hypoxic cultured hMSCs. Within the first culture quarter, cells in both conditions consisted majory of small RS/SS cells and very low FC cells. The second quarter revealed an slight increase of FC cells for normoxic cells and nearly no changes for hypoxia. 100 cells were evaluated per culture condition and time point. RS: rapidly selfrenewing cells, SS: spindle-shaped cells, FSS: flattened spindle-shaped cells, FC: flattened cells.
Results 31 During the third quarter the majority of normoxic cells had flattened morphology. For the same interval, hypoxic cultured hMSCs still preserve their small and spindleshape character (Fig. 15A). In the last quarter before complete senescence most cells in both culture conditions showed a strongly increased cell area with a flattened appearance (Fig. 15B). Detailed values for cell area and aspect ratio are also given in table 4. Fig. 15: Quantification of cell area and aspect ratio of normoxic and hypoxic cultured hMSCs. The third quarter ended with an additional cell area increase for normoxic cells, while hypoxic still keep their small and homogenous morphology. Directly before senescence the cells in both experimental settings had the typical flattended morphology. 100 cells were evaluated per culture condition and time point. RS: rapidly self-renewing cells, SS: spindle-shaped cells, FSS: flattened spindle-shaped cells, FC: flattened cells.