Effect of human umbilical cord blood stem cell transplantation on oval cell response in 2-AAF/CCL4 liver injury model: experimental immunohistochemical study

BACKGROUND: Oval cells, specific liver progenitors, are activated in response to injury. The human umbilical cord blood (hUCB) is a possible source of transplantable hepatic progenitors and can be used in cases of severe liver injury. We detected the effect of hUCB stem cell transplantation on natural response of oval cells to injury. METHODS: Twenty-four female albino rats were randomly divided into three groups: (A) control, (B) liver injury with hepatocyte block, and (C) hUCB transplanted group. Hepatocyte block was performed by administration of 2-acetylaminofluorene (2-AAF) for 12 days. CCL4 was administrated at day 5 from experiment start. Animals were sacrificed at 9 days post CCL4 administration, and samples were collected for biochemical and histopathological analysis. Oval cell response to injury was evaluated by the percentage of oval cells in the liver tissue and frequency of cells incorporated into new ducts. RESULTS: Immunohistochemical analysis of oval cell response to injury was performed. There was significant deviation in the hUCB-transplanted (4.9 ± 1.4) and liver injury groups (2.4 ± 0.9) as compared to control (0.89 ± 0.4) 9 days post injury. Detection of oval cell response was dependant on OV-6 immunoreactivity. For mere localization of cells with human origin, CD34 antihuman immunoreactivity was performed. There was no significant difference in endogenous OV-6 immunoreactivity following stem cell transplantation as compared to the liver injury group. CONCLUSIONS: In vivo transplantation of cord blood stem cells (hUCB) does not interfere with natural oval cell response to liver injury.