To investigate the potential protective effects of OEC‐CM on cell cultures after H/R injury, we supplemented growth medium with three different percentage of conditioned medium, 25%, 50% and 100%, collected from primary OECs cultures at different conditioning times (24, 48 and 72 hrs) (Fig. 1A). Our results showed that in normoxic conditions there was a significant reduction of normalized cell index (CI) in all cell cultures grown in 100% OEC‐CM (Fig. 1B–D), as result of reduced cell confluence and cell number. A similar result, although less marked than previous, was observed when the cells were cultured with 50% OEC‐CM collected after 72 hrs (Fig. 1D). This was probably linked to the lower level of serum and nutrients compared to the fresh medium. Cell cultures grown with 25% and 50% OEC‐CM, collected after 24 hrs and 48 hrs (Fig. 1A and B), did not show any significant difference compared to cells grown in 100% growth medium (CTRL) (Fig. 1A–C). Cells exposed to H/R injury, treated with 25%, 50% and 100% OEC‐CM collected at any time‐points, showed a significant increase of normalized CI compared to CTRL (Fig. 1E–G). Our findings also indicated that OEC‐CM, used at concentrations of 50% and 100%, exerted a higher protective effect on cells compared to 25% OEC‐CM and CTRL (Fig. 1E–G).