One major difference between the two studies is that whereas we formed HC·HA in vitro (with purified human IαI (19), recombinant TSG-6 (42), and medical grade HA), the material used by Zhuo et al. (16) was isolated from the synovial fluids of patients with rheumatoid arthritis. Here, TNFAIP6 is linked to rheumatoid arthritis.