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BACKGROUND: Recent studies have confirmed that the success of stem cell transplantation and the function of transplanted cells are closely related to the in vivo microenvironment. Under normal physiological conditions, the liver is not susceptible to exogenous cells. Therefore, a transplant animal model is usually established to damage the host liver or reduce the immune response of the host liver, creating a good condition for the transplantation and proliferation of exogenous cells. OBJECTIVE: To observe the colonization and distribution of embryonic hepatic stem cells from GFP transgenic mice in a rat model of liposome-coated dichloromethylene diphosphate/retrorsine and 1/3 liver resection (L-CL2MDP/RS/PH). METHODS: GFP transgenic mice at gestational 15 days were taken as donors to separate and cultivate embryonic hepatic stem cells. Fluorescence microscope was used to observe the GFP expression followed by immunocytochemical identification. Thirty Sprague-Dawley rats were randomized into experimental group and control group. Rats in the experimental group were given intraperitoneal injection of retrorsine (30 mg/kg, twice, with an interval of 2 weeks). At 1 preoperative day, these rats were subjected to intravenous infusion of L-CL2MDP (1 mL) and 1/3 liver resection followed by intra-spleen transplantation of embryonic hepatic stem cells from GFP transgenic mice. Rats in the control group were only given injection of normal saline instead of L-CL2MDP and retrorsine, but no liver resection. Frozen liver sections were made in the two groups to observe the distribution of GFP-positive hepatic stem cells under the fluorescence microscope at 3, 15, 30 days after transplantation. Moreover, immunohistochemical staining was used to detect the expression of anti-mouse C-Kit antibody in the rat liver. RESULTS AND CONCLUSION: (1) The hepatic stem cells under microscope were uniform with a cobblestone shape. After 5 days of culture, the cells with increased size presented with the shape of fusiform or polygon, and the green fluorescence was observed in cells under the fluorescence microscope. Passage 3 hepatic stem cells expressed CD34 and AFP. (2) At 3 days after spleen transplantation of embryonic hepatic stem cells, GFP positive cells were scattered in the experimental group under the fluorescence microscope, and the GFP positive expression was still visible in the liver at 30 days after transplantation. (3) At 3, 15, and 30 days after transplantation, C-Kit positive cells were visible in the liver of rats in the experimental group. All these findings reveal that embryonic hepatic stem cells from GFP transgenic mice have been successfully transplanted into the spleen of the L-CL2MDP/RS/PH rat model, and the transplanted cells can survive and proliferate in the rat liver. Subject headings: Liver; Stem Cells; Mice, Transgenic; Tissue Engineering Funding: the National Basic Research Program of China (973 Program), No. 2010CB945502; the Scientific Research Plan Project of Guangdong Province, No. 2015B020226004; the Scientific Research Plan Project of Guangzhou City, No. 201508020262 [ABSTRACT FROM AUTHOR]

BACKGROUND: Retrorsine (RS) is a chemical agent for the long-term inhibition of mature liver cell division and proliferation. OBJECTIVE: To establish a rat model of liver injury by combined use of RS and 1/3 partial hepatectomy, to observe the proliferation of liver cells and oval cells in rats after liver injury, and to discuss the relationship between liver regeneration and mature liver cells and oval cells after liver injury. METHODS: Thirty male Sprague-Dawely rats were randomized into two groups (n=15 per group): RS group and control group. Rats in the RS group were subjected to intraperitoneal injection of RS, 30 mg/kg, twice in total, with 2 weeks in between; and rats in the control group were injected physiological saline instead of RS. Four weeks after the last injection, the 1/3 partial hepatectomy was performed in two groups of rats. Liver pathological and morphological changes as well as cell proliferation were observed, and CK19 and C-kit immunohistochemical detections of the rat liver in the two groups were conducted at different time points after operation. RESULTS AND CONCLUSION: At 20 days after operation, the body mass of the RS group rats was still lower than the baseline, and the liver increase was obviously less than that in the control group; there was cell body swelling shown by hematoxylin-eosin staining, loose cytoplasm, extensive vacuoles degeneration of liver cells, and clustered or scattered oval cells around the portal area of small bile duct and in the hepatic lobule. However, in the control group, the body mass was close to the baseline, liver damage was lighter than that in the RS group, a large number of mature liver cells proliferated under BrdU Immunofluorescence at 20 days after operation; liver oval cells proliferated and distributed in the liver cell line at 14 days after operation, with morphology and immunohistochemical markers consistent with oval cells in the RS group. These findings indicate that the rat model of acute liver injury is successfully established by combining retrorsine with 1/3 partial hepatectomy, liver poisoning and the proliferation of liver stem cells and mature liver cells after poisoning can be seen in the experiment, which firmly confirm that liver cell renewal and regeneration after injury is accredited to the combined action of liver stem cells in liver basin and mature liver cells. [ABSTRACT FROM AUTHOR]