Cell surface epitope characterisation of infrapatellar fat pad cells. Cell surface staining on passage 2 infrapatellar fat pad cells was performed with a panel of antibodies and fluorescein isothiocyanate-conjugated secondary antibody (green), and 4',6-diamidino-2-phenylindole (blue). Results showed strong staining for CD13, CD29, CD44, CD90 and CD105, weak staining for 3G5, and negative staining for low-affinity nerve growth factor receptor (LNGFR), STRO-1, CD34 and CD56. No staining was observed for the IgG control. The staining pattern was confirmed by flow cytometry characterisation and showed the increase in fluorescence (green) compared with the autofluorescence (black).