Bone marrow stromal cells contribute to synovial cell proliferation in rats with collagen induced arthritis.

OBJECTIVE

To observe the migration of bone marrow stromal cells into the joint cavity and the contribution of such cells to synovial proliferation in rats with collagen induced arthritis (CIA).

METHODS

After bone marrow stromal cells preliminarily labeled with fluorescent dye or 3H thymidine accumulated in the bone marrow of splenectomized rats by intraperitoneal injection, the migration of labeled stromal cells in rats with CIA was analyzed by liquid scintillation counting, autoradiography, and fluorography.

RESULTS

In splenectomized control rats, labeled bone marrow stromal cells were mostly found in the bone marrow and not in the synovium. Over 2 weeks after immunization, labeled stromal cells were microscopically found migrating directly into the joint cavity through the area between the articular margin and the synovial insertion (the bare zone). Labeled stromal cells were mainly found in the sublining layers of proliferating synovial tissue.

CONCLUSION

At the onset of CIA, bone marrow stromal cells migrated from the bone marrow into the affected joint cavity and seemed to contribute to synovial proliferation.