Effect of l-arginine deprivation in the medium on differentiation and proliferation of CD34⁺ and CD34^- cells. (A) Expression patterns of lineage differentiation markers in CD34⁺ cord blood cells generated in vitro in the absence of l-arginine in the medium. (B) Changes in the number of cells in culture with or without l-arginine originated from CD34⁺ human cord blood cells. ▪ and □ represent the number of cells cultivated in the medium with l-arginine and without l-arginine, respectively. 1 × 10⁴/mL of CD34⁺ cells were cultured in the presence or absence of l-arginine, and cells were harvested at days 7 and 10. (C) Expression patterns of lineage differentiation markers in CD34^- cord blood cells generated in vitro in the absence of l-arginine in the medium. (D) Changes in the number of cells in culture with or without l-arginine originated from CD34^- human cord blood cells. ▪ and □ represent the number of the cells cultivated in the medium with l-arginine and without l-arginine, respectively. 2 × 10⁵/mL of CD34^- cells were cultured in the presence or absence of l-arginine, and cells were harvested at days 3, 7, and 10. Data represent means of three experiments, and error bars indicate SD.