Morphology and phenotype of WJ-MSC cultured in monolayer and as spheroids. (A). Flow cytometry analysis. Initial population of WJ-MSC used to experiments expressed specific MSC markers (CD73, CD90, and CD105) and less than 1% of WJ-MSC expressed negative markers (CD11b, CD19, CD34, CD45, and HLA-DR). Red histogram—analyzed marker, grey histogram—isotype control. (B). Morphology of 2D and 3D cultured WJ-MSC—monolayer culture of WJ-MSC from 4th passage (up) and WJ-MSC 4 div after formed spheroids (down). (C). Flow cytometry—Forward scatter (FSC) and Side scatter (SSC) analysis for 3D culture (spheroids) and 2D (monolayer). Three days in vitro (div) and 10 div after sphere induction, there were differences in size of cells between 2D and 3D culture. (D). Different morphology of cells cultured as spheroids after reseeding into 2D conditions. Right: WJ-MSC cultured constantly in 2D for 8 passages. Center and left: WJ-MSC from 3D reseeded to 2D condition—visible two different types of morphology: narrow and small (center) and flat and broad (left) cells. White scalebars represent 100 µm.