Fig. 1

BIG can effectively promote the proliferation of OA chondrocytes in a duration-dependent manner. A Cells from the tibial plateau tissue were isolated and cultured. B The cytoplasm and cell membrane of chondrocytes were dark blue, proving that the chondrocytes secreted and synthesized proteoglycans. C The morphology of the red-stained cells was spindle and polygonal, and the nucleus was partial to one side and close to the cell membrane. The fibres of the cells were longer, and the cells were red without green, which shows that the cultured cells secreted proteoglycans. D Toluthanidine blue staining showed purplish-red allochromatic granules with a small number of granules around the cells. Granules were apparent (× 400). E During anti-aggrecan staining, purple abnormal staining granules were found in the chondrocytes, and a small amount of abnormal staining granules appeared around the cells; this phenomenon was more obvious in the formed cell nodule area. After anti-Col2a1 IHC staining, the chondrocyte cytoplasm was stained brown-yellow. The nuclei were uncoloured, and brownish-yellow particles were also observed in the extracellular matrix. F Microscopic pictures showed that BIG promotes chondrocyte proliferation and secretion matrix in chondrocytes (× 400). G The OD 450 value confirmed that BIG increased the concentration of chondrocytes. H The CCK-8 test confirmed that BIG effectively promoted the proliferation of chondrocytes. I BIG produces cytotoxicity in a time-dependent manner. Data are presented as the mean ± SEM (n = 3) and were analysed by the Kruskal‒Wallis test, **P < 0.01, ***P < 0.001