Figure 1

Immunohistochemical staining of BMP-2 in collagenase-induced calcific tendinopathy and central one-third traumatic injury model. (A-E) collagenase-induced calcific tendinopathy and (F-I) central one-third patellar tendon traumatic injury models at different time points. A: week 12 saline-injection control; B: week 2; C: week 4; D-E: week 12 after collagenase injection. F: week 12 sham control; G: week 2; H: week 4; I-J: week 12 after central one-third traumatized injury. For the collagenase-induced calcific tendinopathy group, weak signal was observed at the tendon matrix at week 2. At week 4, matrix around chondrocyte-like cells was also stained. At week 12, the staining was observed mainly in the calcific matrix and the matrix around chondrocyte-like cells. Similar result was observed in the central one-third patellar tendon traumatic injury group though the immunopositive staining of BMP-2 was generally weaker. At weeks 2 and 4, weak signal was observed in the tendon cell matrix. At week 12, the matrix around chondrocyte-like cells and the calcific matrix were stained. No immunopositivity of BMP-2 was observed in both control groups. arrows: tendon cells; arrowheads: chondrocyte-like cells; CR: calcific region; Magnification: 400×; error bar: 100 μm