Susceptibility of human synovial cells in four strains of SCID mice

Human synovial cells from patients with rheumatoid arthritis were transferr ed to four strains of severe combined immunodeficient (SCID) mice. C.B-17-S CID, BALB/cA-SCID, BALB/cA-bg-SCID (beige gene: low natural killer cell act ivity) and RAG2-deficient mice were studied. Synovial tissue-infiltrating c ells were obtained from an explant culture of synovial tissues derived from patients with rheumatoid arthritis. Synovial tissue-infiltrating cells wer e injected into the right knee and dorsal side of foot joint of the animals at 6 weeks of age. Five weeks after the injection, a histopathological stu dy was carried out under light microscope. The study revealed evidence that transplanted human cells made characteristic lesions in the mice, i.e., mu ltiplication of synovial cells, proliferation of fibroblasts, fibrin exudat ion neovascularization, bone and cartilage replacement by connective tissue , and pannus formation. The most remarkable and characteristic lesions were observed in RAG2-deficient mice, then BALB/cA-bg-SCID, BALB/cA-SCID and C. B-17-SCID mice, respectively. A highly reproducible experimental animal mod el of arthritis was established by human synovial cells under in vivo trans fer circumstances. It is possible that the human/RAG2 chimeric model is use ful for studies on the pathogenesis of arthritis and the development or eva luation of therapeutic agents.