Changes in surface markers of human mesenchymal stem cells during the chondrogenic differentiation and dedifferentiation processes in vitro.

OBJECTIVE To investigate surface markers showing specific changes during the chondrogenic differentiation and dedifferentiation of human mesenchymal stem cells (MSCs). METHODS Human MSCs from adult bone marrow were subjected to chondrogenic differentiation in 3-dimensional (3-D) alginate culture with or without transforming growth factor beta3 (TGFbeta3) for 2 weeks, followed by dedifferentiation in monolayer for 1 week. Surface antigens were selected from those previously reported to show changes in expression during dedifferentiation of human articular chondrocytes (HACs). RESULTS Flow cytometry was used to identify 3 groups of surface antigens with differential expression patterns that were quite different from those previously reported on HACs. Two groups of antigens were expressed at high levels on human MSCs. The expression of the first group of antigens (CD44, CD58, CD81, CD90, CD105, and CD166) was decreased reversibly by the 3-D alginate culture and irreversibly in the presence of TGFbeta3, except for CD81, which showed reversible changes regardless of TGFbeta3. The expression of the second group of antigens (CD49c, CD49e, and CD151) was decreased during chondrogenic differentiation only in the presence of TGFbeta3. During all experimental stages, the expression of the third group of antigens (CD14, CD26, CD49f, CD54, CD106, CD119, and CD140a) was maintained at low levels (expressed on <30% of cells), although with some fluctuations. CONCLUSION We speculate that the second group of surface antigens could be negative markers for chondrogenic differentiation of human MSCs.