Synovial membranes from patients with OA contain more cells positive for CD44, CD90, and CD105 antigens than those from joints with undamaged cartilage.

Synovial membranes from OA patients contain more cells expressing CD271 antigen than those from healthy joints, and spontaneous cartilage repair tissue contains cells positive for CD271 antigen. These data suggest the involvement of CD271 antigen in spontaneous cartilage repair and indicate that the cell subset MSC CD271+ provides higher quality chondral repair than the CD271- subset.