Figure 5.

Experimental design of co-culture experiments of primary osteoblasts (OB) with either nucleus pulposus cells (NPC), annulus fibrosus cells (AFC), cartilaginous endplate cells (CEPC) or 6 empty beads as positive control. OB were cultured as monolayer at the bottom of the well, intervertebral disc (IVD) cells were seeded in 3D alginate beads (~30 µL) on the top in the insert with 0.4 µm pore size. All experimental groups and positive control were stimulated with osteogenic medium (α-MEM supplemented with 10% FBS, 100 μg/mL penicillin/streptomycin, 50 µg/mL l-ascorbic acid-2-phosphate, 10 nM dexamethasone and 5 mM β-glycerophosphate). Negative control was stimulated with basal medium (α-MEM + 10% FBS).