Western blot results show that both fr- and ds-HMGB1 are expressed in the extracellular matrix of aging mouse tendon, but Met treatment nearly eliminates dsHMGB1, reduces frHMGB1 to the level close to that of young tendon, decreases the expression of inflammatory macrophage marker CD68, and senescent markers CCN1 and p16 expression in aging tendon (A). Semi-quantification of the Western blot shows the increased levels of both frHMGB1 and dsHMGB1in aging tendon, but Met treatment decreases both frHMGB1 and dsHMGB1, with dsHMGB1 nearly absent (B). *p < 0.01 (19M compared to 4M); #p < 0.01 (19M+Met compared to 19M).