A transgenic animal model for evaluating growth, survival and/or metastasis of xenotransplanted normal or tumor cells or tissue is disclosed, in which a human growth factor, hHGF stimulates growth in vivo of human cells or tissue. A strain of Tg mice on the C3H background that is immunocompromised as a result of a homozygous scid gene has been bred which express a nucleic acid encoding hHGF/SE The ectopically expressed hHGF/SF ligand significantly enhances growth of human tumor cell lines and explanted tumor cells or tissue that express the Met receptor for hHGF. Such animals also have an enlarged normal livers and greater than normal liver regenerative capacity. Any Met-expressing hHGF-dependent human cells, including hepatocytes and various stem cells can survive and grow in such animals.