Activation of reparative liver regeneration following the combined transplantation of multipotent mesenchymal stromal cells and hepatic stellate cells

Aim. To study the effect of combined transplantation of multipotent mesenchymal stromal and hepatic stellate cells on the reparative liver regeneration.

Methods. Laboratory mice were given intravenous administration of multipotent mesenchymal stromal and hepatic stellate cells after partial hepatectomy. The mice were divided into four groups: control, experimental 1 (injection of multipotent mesenchymal stromal cells), experimental 2 (co-transplantation of multipotent mesenchymal stromal cells and hepatic stellate cells), the comparison group. Comparison of the experimental groups with the control group and the comparison group was carried out. Each group consisted of 14 animals. The control and experimental groups underwent partial hepatectomy. The experimental mice were injected with the cells into the lateral tail vein 1 hour after the operation. Multipotent mesenchymal stromal cells were administered at a dose of 4 million cells/kg (120 thousand cells/mouse), hepatic stellate cells — in the amount of 9 million cells/kg (270 thousand cells/mouse), suspended in 0.2 ml 0.9% NaCl solution. The control group animals were injected with 0.2 ml 0.9% NaCl solution into the lateral tail vein. The comparison group consisted of mice without partial hepatectomy, injected with 0.2 ml 0.9% NaCl solution. To assess reparative regeneration of the liver, morphometric parameters of the liver, blood biochemical parameters on the 3rd and 7th days after partial hepatectomy were studied. The severity of apoptosis was assessed by the immunohistochemical method, the activity of deoxyribonucleic acid (DNA) repair enzymes of the poly (ADP-ribose) polymerases was determined by flow cytometry. The number of micronucleated hepatocytes was also determined. The hepatocyte growth factor (HGF) content was measured by using an enzyme-linked immunosorbent assay in serum. The significance of differences in the compared samples was determined by using the Student's t-test. Statistical data processing was performed by using the SPSS Statistics software version 17.0.

Results. It was found that the combined transplantation of multipotent mesenchymal stromal and stellate liver cells causes restoration of the activity of alanine aminotransferase (a decrease of 30.3%, p=0.016), aspartate aminotransferase (a decrease of 27.7%, p=0.021), alkaline phosphatase (a decrease of 21.1%, p=0.036), an increase in the protein synthetic function of the liver (increase in albumin level by 36.6%, p=0.009), an increase in hepatocyte growth factor level by 74.3%. These changes were accompanied by the restoration of liver morphometric parameters: there was an increase in the mitotic activity of hepatocytes by 28.7% (p=0.008), the nuclear area of hepatocytes by 26.7% (p=0.006), the number of binucleated hepatocytes by 26.1% (p=0.004), which led to the restoration of liver mass. There was a decrease in the level of apoptosis by 28.8% (p=0.006) and a decrease in the number of micronucleated hepatocytes by 22.7% (p=0.001) compared with the control group, which may be related to an increase in the activity of Poly (ADP-ribose) polymerase repair enzymes detected in the study. The deviations were presented as a difference relative to the indicators of the control group (operated animals that were injected with 0.9% NaCl solution).

Conclusion. Combined transplantation of multipotent mesenchymal stromal and hepatic stellate cells activates reparative liver regeneration after partial hepatectomy.Keywords: multipotent mesenchymal stromal cells, MSC, hepatic stellate cells, HSC, liver regeneration, partial hepatectomy.