Single-cell RNA-seq analysis of nonchondrocytes from healthy and OA patients. (a) UMAP plot of 259 single cells from the human knee depicting 3 nonchondrocyte cell types. (b) Bar plot shows frequency of each cell type in the healthy and OA groups. (c) Split UMAP plot depicting the nonchondrocyte clusters from healthy (N) and OA patients (O). (d) Heat map indicates the top 10 marker genes for each cell type. (e) Expression distribution of the top marker genes for the nonchondrocytes projected onto the UMAP plot. (f) Expression distribution of top markers in the monocyte cluster. (g) Expression distribution of top markers in the macrophage cluster.