Fig. 1. Schematic cross-sectional overview of the different defect filling conditions in the ex vivo OC plug model.

Chondrocytes were seeded at the bottom of the defect (A, 20x10⁶ cells/ml), homogeneously in the hydrogel (B, 20x10⁶ cell/ml), both at the bottom of the defect and in the hydrogel (C, 10x10⁶ cell/ml + 10x10⁶ cell/ml, respectively; D, 20x10⁶ cell/ml + 20x10⁶ cell/ml, respectively). An empty hydrogel was used as control (E). All defects were filled with a total of 10 μl hydrogel. To evaluate the influence of the ex vivo OC plug model on the tissue production of the delivered chondrocytes, a cell-laden hydrogel control (HC, 20x10⁶ cell/ml) also was cultured.