Fig. 1

Experimental design and characteristics of human intervertebral disc-derived cells. a Schematic illustration of the experimental paradigm adopted in this study. b Morphology of the cells (passage 3) derived from human intervertebral discs. c Quantitative real-time reverse transcription-polymerase chain reaction demonstrated high expression of chondrogenic marker genes, aggrecan (ACAN), SRY (sex determining region Y)-box9 (Sox9), and type II collagen (Col2A1), in the disc cells compared with adult dermal fibroblasts, urine cells, and adipose-derived stromal cells (ADSCs). All cell types were analyzed at passage 3. *P < 0.01 (n = 3). hDF human dermal fibroblast, iPSC induced pluripotent stem cell, NPC neural precursor cell