MMP9 and rheumatoid arthritis: In the presence of MMP-9, 6-loaded PRNPs (6-PRNPs) showed high cellular uptake in both human synovial macrophages and osteoclasts derived from late-stage RA patients undergoing joint replacement surgery, via RGD-αvβ3 integrin interaction, thus enhancing the apoptosis of the forementioned cells [72].