Fig 2: The receptors and signaling pathways that are activated in NGF-induced BMSCs in vitro and in vivo. (a-d) qRT-PCR was to determine the expression levels of the ACAN, SOX9, COL2A1 and COL1A1 genes in the repaired model after 4, 8 and 12 weeks. (e) Western blots was used to analyze the protein expression levels of Col1A1 and COL2A1. (f and g) Western blots was used to analyze the protein expression levels of the NGF receptors TrkA and p75 in vitro (f) and in vivo (g). (h and i) Western blots was used to analyze the protein expression of proteins in the PI3K/AKT signaling pathway, including PI3K, AKT and p-AKT, in vitro (h) and in vivo (i). (j and k) Western blots was used to analyze the expression of proteins in the ERK/MAPK signaling pathway, including ERK, p-ERK, P38 and p-P38, in vitro (j) and in vivo (k). (l) Schematic description of the relevant signaling pathways that were activated by NGF. The values are means±S.D., n=10 joints; bars with different letters are significantly different from each other at P<0.05

Fig 3: Chondrogenic effects of NGF on BMSCs grown in 3D cultures. (a and b) Immunohistochemical staining of COL1A1 (a) and COL2A1 (b) was performed in the cultured constructs on days 7, 14 and 21. (c) qRT-PCR was performed to determine the expression levels of ACAN, SOX9, COL2A1, COL1A1, RUNX2, ENO2, GDNF, BDNF and CNTF in the cultured constructs on 7 14 and 21 day. (d) Western blots was used to analyze the protein expression levels of Col1A1 and COL2A1. The values are means±S.D., n=6; bars with different letters are significantly different from each other at P<0.05, Scale bar=100 μm

Fig 4: Chondrogenic effects of NGF on BMSCs in vivo. (a) Safranin O staining were performed on cartilage sections. (b and c) Immunohistochemical staining of COL1A2 (b) and COL1A1 (c) were performed in cartilage sections. (Original low magnification × 40 (scale bar, 500 μm); original high magnification × 200 (scale bar, 100 μm))