Fig. 4

CD271⁺ cartilage-derived cells: loss of CD271⁺ phenotype and response to NGF during in vitro culture. a Abundance of CD271⁺ cells in the cartilage-derived cells determined by flow cytometry. Passages in culture: P0, 33.60 ± 5.09 %; P1, 3.00 ± 2.33 %; P3 and P5, signal undetectable (P0 versus P1: *p <0.05; n = 5, biological replicates; mean ± SD). b CD271⁺ cells (%) at P3, after treatment with 10 ng/ml NGF for 24 hours. Representative sample is shown (n = 3). c Early-passage cells isolated from healthy cartilage (passage 1 (P1); n = 3, biological replicates, mean ± SD) and late passage from OA articular cartilage (passage 4 (P4); n = 5, biological replicates, mean ± SD) are not chemotactic for NGF (10 ng/ml), p >0.05. d CSPC proliferation (n = 4). e Gene expression profiles of COL2, AGN, MMP2/3/13, and ADAMTS-4/5, in CSPCs before and after NGF (10 ng/ml, 48 hours) and IL-1β (100 pg/ml, 48 hours) treatment. IL-1β versus control: *p <0.05, n = 5, biological replicates, mean ± SD, values normalized to RPL13a. ab NGF neutralizing antibody, ADAMTS a disintegrin-like and metalloproteinase with thrombospondin motifs, IL interleukin, MMP matrix metalloproteinase, NGF nerve growth factor, OA osteoarthritis