Direct effect of HGF on thymopoiesis. BDF1 (Ly5.2) recipients were irradiated (9 Gy) and received TCD bone marrow cells (5 × 10⁶) from B6 (Ly5.1) donors. HVJ liposomes containing 8 μg human HGF cDNA or a mock vector were injected intramuscularly on days 0, +7, and +14 of BMT. On days 14 and 21 after BMT, the number of Ly5.1⁺ cells (A) and Ly5.1⁺CD3⁺ cells (B) in the spleen and the number of Ly5.1⁺ cells in the thymus (C) were analyzed by flow cytometry. □ indicates control-treated BM transplant recipients; and ▦, HGF-treated BM transplant recipients. Data represent the mean ± SD from 3 mice. ^*P < .05. ^**P not significant. Representative results from 2 similar experiments are shown.