Figure 3.

Isolation, culture and identification of primary nucleus pulposus (NP) cells. (A) Primary NP cells were obtained by enzymatic digestion (magnification, ×100). (B) Degenerated NP cells from passage 2 attached to the culture dish after passage for 3 h (magnification, ×100). The primary NP cells derived from degenerative human disc were round at the moment of isolation (A) and they had attached to the culture dish after 5–7 days of culture. The cells gradually became elongated and triangular or polygonal in shape, and the cytoplasm became plump and equally distributed. The number of attached cells exponentially increased. (C and D) Immunostaining revealed that these cells were positive for aggrecan and type II collagen, which are makers of the NP cell phenotype (magnification, ×100).