Table 1. Specific cell surface markers reported to be expressed in chondrocytes and chondroprogenitors from normal and osteoarthritis (OA) cartilage tissue.

CD44 is a common marker between chondrocytes and chondroprogenitor cells in normal cartilage. CD90, CD105 and CD166 are common markers between chondroprogenitor cells in normal and OA cartilage.

Cell type	Distinguishing positive cell surface markers
Chondrocyte	. (37,66)
Chondroprogenitor (normal cartilage)	. (7,10,35,36)
Chondroprogenitor (OA cartilage)	. (5,8)