Histological analysis
The mouse knee samples were fixed with 4% paraformaldehyde solution for
48 h and then decalcified with 0.5 M ethylenediaminetetraacetic acid
(EDTA) until the tissues became soft. The samples were embedded in
paraffin and cut into 5 mm sections by a microtome. The tissue sections
were subsequently stained with safranin O and then observed by optical
microscopy. The OARSI grading system (0–6) was used to evaluate the
sections.