A range of assays have been developed to determine the stemness or stem cell activity of human stem cells. The key assays of stem cells are functional: they must show self-renewal and the ability to generate the appropriate tissue. The best assays available to study this property in putative human stem cells involve xeno-transplantation into immune-deficient mice. Demonstration of both long-term (2-3 months) multi-lineage reconstitution of human blood or liver in a murine host and the ability of the putative stem cells to mediate reconstitution of a secondary host upon re-isolation from the primary mouse are generally accepted as the gold standard for demonstrating the presence of human hematopoietic and hepatic stem cells. Here, we describe a method of reconstituting NOD-scid IL-2Rγ^-/-(NSG) mice with CD34⁺ stem cells from human fetal liver and repurification of CD34⁺ cells for serial transplantation.

Hematopoietic progenitor (Hematopoietic祖)

Hepatic progenitor (肝祖)

Immune system (免疫系统)

Human Hepatocyte (人肝细胞)

Chimera mouse (嵌合体小鼠)