Fig. 1

Histopathological observation, IHC analysis, and pain behavior tests on the in vivo effects of hucMSCs, SF, and SF-stimulated hucMSCs on kOA rats. A Safranin O/Fast green staining on cartilage with black arrows (hypertrophy or loss of chondrocytes). Scale bars = 50 μm. B IHC staining of Col2 and MMP13 on cartilage with red arrows (positive cells). Scale bars = 50 μm. C OARSI and Mankin’s scoring of histopathology. D Quantitative measurements of the percentage of Col2-positive area and MMP13-positive cells. E Measurement of MWT and TWL of rats. Data expressed as mean ± SD. The different letter symbols (a, b, bc, c, cd, and d) indicate significant difference between each other (Fisher’s LSD, P < 0.05 or P < 0.01) in the descending order of data from a to z. Although the overlapped letters (b versus bc, bc versus c, c versus cd, and cd versus d) were statistically different, their difference between each other was not significant. All experiments were repeated at least three times