Fig. 1

Surface marker analysis and sorting strategy to identify progenitors with robust chondrogenic potential from heterogenous chondroprogenitor (CP) cells. a Flow cytometry showed approximately 4.27% of cells expressed COL2A1-GFP. b, c Chondroprogenitors were labeled for various surface markers and analyzed for co-expression with COL2A1-GFP. b Most COL2A1-GFP⁺ cells did not express CD271, CD105, CD73, and BMPR1β. c PDGFRβ, CD146, and CD166 were co-expressed with COL2A1-GFP. d A schematic representing the experimental design. The RVR cell line with the COL2A1-GFP reporter was differentiated into chondroprogenitor cells. Surface marker analysis indicated that PDGFRβ, CD146, and CD166 expression were highly co-expressed with COL2A1 but not CD45. e Cells expressing these desired markers were sorted from wildtype BJFF chondroprogenitor cells. To evaluate the chondrogenic potential of the sorted cells, pellets from the sorted cells were either made immediately post-sorting or formed after in vitro expansion. f A higher percentage of the total cell population (~ 16.8%) was triple positive for the desired markers compared to the population not expressing any of these markers. *p < 0.05. Data represented as mean ± SEM. n = 7–8 independent experiments. See also Figure S1