OBJECTIVETo observe the in vivo colonization, migration, and differentiation of in vitro cultured human fetal hepatic stem cells (HSCs) following intrasplenic transplantation for treatment of acute liver injury in mice with severe combined immunodeficiency (SCID).

METHODSHuman fetal HSCs were isolated from the normal fetal liver (16-24 weeks) and purified, and the morphology of HSCs was observed under optical and transmission electron microscopes. The expressions of stem cell markers were examined in these HSCs by means of immunocytochemistry and flow cytometry. The passaged human fetal HSC suspension (0.2 ml) were injected into the spleen of SCID mice with acute liver injury induced by two-third partial hepatectomy, and 15, 30, 60, and 90 days after cell transplantation, immunohistochemistry was performed to examine the location and expressions of human hepatocytes, alpha1-AT and AFP antigen in the spleen and liver of the recipient SCID mice. PAS staining was used to examine the expression of glycogen and RT-PCR employed for detection of the expressions of AFP and albumin mRNA in the spleen of the mice on the scheduled time points.

RESULTSUnder optical microscope and transmission electron microscope, most of the HSCs were small, about 1/6 to 1/3 of the size of the hepatocyte, with relatively large nucleus-cytoplasm ratio and only small quantities of endocytoplasmic reticulum, chondriosome, and ribosome. Immunohistochemistry and flow cytometry identified positive expressions of AFP, Thy-1, C-kit, CD34 and CK19 in the HSCs, and after cell transplantation, positive expressions of human hepatocyte, alpha1-AT, and AFP antigen occurred in the liver and spleen of the recipient SCID mice. PAS staining confirmed the presence of glycogenosome in the spleen of the mice following cell transplantation. RT-PCR on days 30, 60, and 90 showed positive expressions of human AFP and albumin mRNA in the spleen of the mice.

CONCLUSIONHuman fetal HSCs can survive and settle in the spleen and liver, and migrate to the damaged liver of the recipient mice after intrasplenic transplantation, with the capacity of proliferation and differentiation into hepatocytes in the recipient target organs.