Fig. 1: Aggrecan localization in normal and OA synovial MPCs.

In normal synovial MPCs, aggrecan staining is present throughout the cytoplasm (A–C), with areas of increased staining observed adjacent to the nucleus (C, arrow, G—representation). In OA synovial MPCs, little to no cytoplasmic staining is observed (D–L), instead intense staining is observed only adjacent to the nucleus (F, arrows, H—representation). When OA MPCs were doubled labeled for aggrecan (G3 polyclonal) (O) and a marker of the endoplasmic reticulum (KDEL, P), the majority, but not all of the aggrecan staining appeared to be within the endoplasmic reticulum (Q, arrows). Secondary antibody alone controls demonstrate minimal non-specific staining (M, N). Scale bars equal 10 µm (A–L), 20 µm (O–Q).