Liver functions comprise over 500 procedures to protect the body system of the living creatures, including metabolism of the absorbed materials from the intestines, storage of the processed materials in the cells, production of many proteins, detoxification of unnecessary food materials, drugs and alcohols and many more. Therefore if the liver is damaged by cirrhosis we will observe weakness, anorexia, skin rash, discolorations, edema and in advanced cases there will be infectious peritonitis, esophageal hemorrhage, ascites and nervousness due to undigested ammonia and its impact on CNS (8).
We could induce liver cirrhosis by the ligating of the bile duct as Marques etal. did; they found that ligation of the bile duct induces liver cirrhosis in shorter time than CCL4 administration (9 weeks vs. 16 weeks) (9). But this was not considered in this study, since the method would develop many structural changes around the ligated bile duct and liver; so it would have not been possible to see the effects of stem cell or any other drugs well. Addition of olive oil to CCL4 lets gradual absorption of CCL4 from the peritoneal cavity.
There have been many researches trying to reverse the liver cirrhosis in animal models such as studies on the preventive effect of curcumin on liver cirrhosis induction in rat models by CCL4, which revealed that daily oral administration of curcumin improves liver cirrhosis and fibrosis (10, 11). In another study, the positive preventive effect of the coffee on rats' cirrhotic liver induced by CCL4 was evaluated (12). Uzma etal. induced liver cirrhosis in rats by CCL4 and treated them by red wine demonstrated that red wine has powerful protective impact on cirrhotic liver due to its antioxidant effect, activation of immune system and anti-inflammatory effects (13).
Administration of stem cells for treatment of liver failure and cirrhosis were also assessed in many studies (14). Takami etal. used bone marrow derived stem cells to treat chronic liver diseases and showed improvement in clinical outcomes (15). Stem cells derived from amniotic membrane and bone marrow could treat liver fibrosis in rats, which suggests the potential effects of these stem cells for liver regeneration and reconstruction (16). Also, autologous bone marrow derived stem cells could treat liver cirrhosis as a safe procedure (17, 18). And the health-related quality of life was studied in patients who received stem cell therapy for end-stage liver disease (19).
In the present study, we used mesenchymal stem cells derived from the mesenteric fat to treat the liver cirrhosis induced by CCL4 in a period of 16 weeks. These stem cells were able to prevent cirrhosis advancement, they could transform the fat colonies to hepatocyte colonies, reduce the connective tissue in the parenchyma and transform them to hepatic cells, so that the liver color changed from creamy yellow to nice liver red color. The liver surface nodular appearance was also changed to normal smooth surface. The stem cells were able to alter the clinical signs of liver cirrhosis so that the rats looked healthier, more alert, more sociable, showing more appetite. These clinical signs appeared after 30 days post stem cell injection.
It is suggested to extend post-op evaluation to 60 days in future studies to have better clinical and pathological assessments. We also injected the stem cells only once, and it is not clear that any second injections would be beneficial to cirrhotic conditions or may compromise the state of previous injected stem cells and their newly laid down tissues.
All previous studies have been used stem cells derived from bone marrow (15, 20), umbilical cord (21) the liver itself (22) or hepatic cell line (23) and the amniotic membrane (16), but in this study we used mesenteric adipose tissue to harvest stem cells and applied a modified technique which proved good results clinically and histopathologically. Few animal studies administered adipose stem cells (ADSC) for hepatic regeneration with different methods (24, 25). Sakai etal. also enrolled a clinical trial in 2017 based on intrahepatic arterial infusion of autologous subcutaneous adipose tissue stem cells for liver cirrhosis, but it is not completed yet (26). It seems that the therapeutic effect on the symptoms of cirrhosis is based on ADSC-secreted growth factors (HGF & VEGF), anti-inflammatory effects on hepatic stellate cells, and the anti-fibrotic and angiogenic effects of ADSC-secreted proteins (27).
In most researches they injected the stem cells into portal vein, but this study tried to inject stem cells directly into cirrhotic liver parenchyma beside portal vein injection, because of high portal vein pressure due to cirrhosis. This technique have some advantages such as avoiding much manipulation of high pressure portal vein and its subsequent hemorrhage, preventing cardiac arrhythmias and finally patient fatality. Also it will give us opportunity to inject the prepared stem cells directly into the liver parenchyma from the abdominal wall without opening the peritoneal cavity using ultrasound or CT scan guide, which should be investigated in future.
These studies are very attractive for developing effective anti-cirrhotic therapies. Researches are needed to determine the most valuable cell source, culture condition, cell number, administration frequency, and administration route, at low cost for treating liver diseases (28).