Figure 4: Differentiation of human adult spinal disc stem cells into NP cells, and characterization of their phenotype. Single stem cell suspensions derived from discospheres were plated on cover slips coated with 50 μg/ml laminin in chondrogenic media supplemented with 10% fetal calf serum, and chondrogenic culture conditions, for 14 days. A. Photomicrograph taken with light microscopy at 10X magnification of NP cells differentiated from spinal disc stem cells over 14 days, at 70% confluency. B. Photomicrograph taken with light microscopy at 10X magnification of NP cells differentiated from spinal disc stem cells over 14 days at 100% confluency. C. Photomicrograph taken with light microscopy at 20X magnification of NP cells differentiated from spinal disc stem cells over 14 days at 100% confluency. D. Photomicrograph taken with light microscopy at 40X magnification of NP cells differentiated from spinal disc stem cells over 14 days at 100% confluency. Escalating photomicroscopic magnifications are shown to demonstrate the significant amount of secreted extracellular matrix in differentiated mature confluent NP cells.