MMP9 and cyclic hematopoiesis: As shown in Figures 6C,D, the gene expression levels of both COL3A1 and MMP9 increased in the OA-CH group, and IL-1β promoted the expressions of COL3A1 and MMP9. Notably, the expressions of COL3A1 and MMP9 increased as the concentration of IL-1β increased.