Human dental pulp cells are isolated from the dental pulp of extracted molars. Human dental pulp cells are isolated from a single donor. These cells enable researcher to investigate stem cells, regenerative dentistry, and tissue engineering and repair in vitro. In addition, they enable researchers to investigate diseases. Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs but principally attacks the joints, producing an inflammatory synovitis that often progresses to destruction of the articular cartilage and ankylosis of the joints.