Induction of collagenase induced OA mice model

Thirty male C57/BL6 mice aged 8–12 weeks were randomly divided into five groups with six for each group: (1) control group, (2) OA + isotype IgG group, (3) OA + Cadherin-11 antibody group, (4) OA+ LY2940002 (PI3K/Akt inhibitor) group, and (5) OA + DMSO group.

Experimental OA mice model was induced as previously described [16]. In brief, the procedure involves intraarticular administration of 10 μl collagenase VII (containing 1 unit collagenase) (Sigma, St. Louis, MO) in the right knee on day 0 and day 2.

After 2 weeks of collagenase induction, 2 μg isotype IgG (ZSGB-BIO, China, ZDR-5001) or Cadherin-11 antibody (sc-30,314, Santa-Cruz, USA) was separately intraarticularly administered twice a week for 2 weeks. Then, the mice were euthanized with CO₂, and the right knees were isolated and processed for histological examination.

After 2 weeks of collagenase induction, 1 mg LY294002 dissolved in 200 μl 8%DMSO diluted by PBS was inoculated intraperitoneally (i.p.) daily for 2 weeks. Two hundred microliters of 8%DMSO-PBS was inoculated i.p. daily for the control group. After 2 weeks, the mice were euthanized with CO₂, and the right knees were isolated and processed for histological examination.