*2.6. Multichromatic Flow Cytometry*

A panel of 12 surface markers was used in multichromatic flow cytometry to assess the phenotype of the cells. The harvested cells were blocked with human IgG (Grifols, Cambridge, UK) for 1 h, washed with PBS and incubated for 30 min with antibodies against the mesenchymal stromal/stem cell (MSC) markers CD73, CD90 and CD105 putative chondropotency markers CD151, CD166, FGFR3, CD44 and integrins CD29, CD49a, CD49b CD49c, CD51/CD61 (all BD Biosciences, except for FGFR-3 which was sourced from R&D Systems). The matching isotype controls for each antibody were also prepared according to manufacturer's recommendations. At least 5000 cells were measured per marker via a FACS Canto II cytometer and analysis was performed using the FACS Diva software.
