Figure 1.

SDF-1/CXCR4 interactions mediate homing and engraftment of irradiated NOD/SCID mouse liver by human CD34⁺ cells. (a) Homing of human CB or MPB enriched CD34⁺ cells to the murine BM, spleen (Spl), and liver is inhibited by neutralizing CXCR4. Data present inhibition as percentage of control. P ≤ 0.008, comparing anti-CXCR4–treated samples with their control counterparts. (b) A representative homing experiment shows human CD34⁺/CD38^–/low homing cells (gated) in the liver of mice transplanted with nontreated cells (top), or CXCR4-neutralized cells (middle). A noninjected (Non-inj) mouse served as a negative control (bottom). Numbers indicate human homing cells/1.5 × 10⁶ acquired cells. (c) Four-hour homing of CXCR4-neutralized or nontreated CD34⁺ cells to the liver of nonirradiated mice. Human SDF-1 was injected into the liver parenchyma as indicated. Cells were collected from the injected lobe to determine the homing of human CD34⁺ cells. (d) Human cell engraftment of the liver by CB nonstimulated CD34⁺ cells or CD34⁺ cells that migrated toward SDF-1, determined by Southern blot specific for human DNA. A representative blot is shown (*mouse transplanted with CD34⁺ cells migrating toward SDF-1). (e) Data as presented in d, summarizing three independent experiments (n = 37 mice). (f) SDF-1 levels in liver extracts of mice with no irradiation (ctrl), 24 hours and 48 hours after irradiation, determined by ELISA. Data summarize three experiments.