Figure 4From: Relative percentage and zonal distribution of mesenchymal progenitor cells in human osteoarthritic and normal cartilageMicroscopic images and corresponding FACS analysis of chondrocytes before and after immunomagnetic separation. After incubation with bead-coupled antibodies to the surface antigen CD166, both membrane-bound and free magnetic anti-CD166 particles are visible, as are non-labeled chondrocytes (a1). In the positive fraction after separation, only magnetobead-covered CD166+ cells and free magnetobeads are present (b1). In the negative fraction, only CD166- cells without magnetobeads are present; also, no free magnetobeads are present (c1). These results were confirmed by FACS analysis, demonstrating an enrichment of CD166+ cells from 10% before (a2) to approximately 87% after (b2) separation, whereas the negative fraction contained only a very low percentage of CD166+ cells (c2). FACS, fluorescence-activated cell sorting; FITC, fluorescein isothiocyanate.Back to article page