Morphological Features of the Synovial Membrane and Articular Cartilage in Rats under Simulated Adjuvant Arthritis and Application of Allogeneic Biomaterial

The aim of research was to study morphological features of the synovial membrane and articular cartilage of rats under simulated adjuvant arthritis and application of allogeneic biomaterial.Material and methods. To simulate rheumatoid arthritis, 12 white outbred female rats were injected 100 μl of complete Freund's adjuvant into the plantar surface of the hind paw. In 7 days, 5 mg of the allogeneic biomaterial “Regeneration stimulator” dissolved in physiological solution was injected into the periarticular bursae of the right knee joint and surrounding tissues in the rats of the main experimental group (n=6). Saline solution was injected into animals of the main control group (n=6). Intact rats (n=6) were included in the intact control group. All the animals were withdrawn from the experiment in 37 days after the onset of the experiment. The knee joints of rats were examined using standard histological, morphometric and statistical methods.Results. Animals of the main control group manifested signs of degenerative changes of varying degrees in the articular apparatus. Proliferation of the synovial cells and tissue hyperplasia were detected in the synovial membrane, these leading to the formation of pannus. There was disorganization of the connective tissue: they were thinned, the fibrous layer was separated, the cartilage and bone tissue were destructed. In animals of the experimental group, there were no signs of tissue hyperplasia and edema, pronounced pannus were not detected after the introduction of the allogeneic biomaterial in the synovial membrane. Mild signs of arthritis manifested as slightly increased processes of the synovial cell proliferation and moderate perivascular infiltration with cellular elements were detected in 2 rats. There were no changes in the structure of the cartilage and bone in the knee joint.Conclusion. Intraarticular injection of the allogeneic biomaterial "Regeneration Stimulator" in rats with simulated autoimmune rheumatoid arthritis is accompanied by a decreased external manifestations of a generalized inflammatory process in the knee joints, and by a decreased inflammation and degenerative changes in the articular apparatus at the tissue level. Notably, the structures of the synovial membrane, the articular cartilage of the knee joint and the underlying subchondral bone are preserved compared with animals of the control group.