Figure 2
Experimental study set-up. (A) Human ASCs were cultured for 2–3 weeks until desired cell concentration was reached. Then, 250,000 cells per pellet were spun down to induce pellet formation, which was completed within 3 days. Pellets were divided into 3 groups: unstimulated static control for 42 days (nHP), hydrostatic pressure stimulated (HP) for 42 days, no stimulation for 21 days followed by HP stimulation for 21 days (nHP → HP). Pellets were harvested on day 0, 3 and 7 and from then on every seventh day for the total period of the experiment. (B) The hydrostatic pressure stimulation protocol. After 3 days of initial pellet formation, pellets were subjected to 4 hours of intermitted stimulation in a 2 s on/off manner with a maximum and minimum pressure of 4 and 0 bars, respectively. Each stimulation phase was followed by a no pressure period of 20 hours. This regime was repeated for 5 consecutive days per week with 2 resting days in-between. This pattern was repeated until the end of the experiment on day 42.
