Fig 2: Evaluation of the CD marker location in the synovial membrane. Immunohistochemical analysis using DAB (3, 3'-diaminobenzidine, orange/brown staining) was performed to identify the location of CD90, CD44, CD73, CD271, and CD34 expression in the normal (circle) and osteoarthritic (OA, square) synovial membrane. Representative images, containing both fibrous and adipose type synovial membrane, were chosen. The scale bar is set at 50 µm. Quantification of the DAB staining was performed with Image ProPlus 6.0 software (Media Cybernetics) in 3 to 6 random regions of interest (ROI) per donor, resulting in a mean percentage of DAB positive staining areas for each donor

Fig 3: Graphical overview of the CD marker expression in the synovial membrane. A Synovial membrane (SM) was collected from normal and OA knee joints B Immunohistochemical staining was performed for CD90, CD44, CD73, and CD271. Tissue expression of these markers is visualized in red. Immunopositivity of CD90 was observed mainly in the subintimal and perivascular layer. CD44 was mainly expressed in the intimal lining cells, although variable expression was observed in the subintimal layer and perivascular. CD73 positive cells were mostly observed in the intimal lining and perivascular layer. CD271 was expressed perivascular and in the normal SM also in the intimal layer of the adipose parts of the synovial membrane