Urine-derived stem cells accelerate the recovery of injured mouse hepatic tissue

Urine-derived stem cells (USCs) are autologous stem cells that exhibit self-renewal ability and multi-lineage differentiation potential. These characteristics make USCs an ideal cell source for hepatocellular transplantation. Here, we investigated the biological characteristics of USCs and their potential use for the treatment of chronic liver injury. We characterized the cell-surface marker profile of USCs by flow cytometry and determined the osteogenic, adipogenic, and hepatic differentiation capacities of USCs using histology. We established a chronic liver-injury model by intraperitoneally injecting carbon tetrachloride into nude mice. USCs were then transplanted via tail vein injection. To determine liver function and histopathology following chronic liver injury, we calculated the liver index, measured serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, and performed histological staining. USCs were small, adherent cells expressing mesenchymal but not hematopoietic stem-cell markers. Some induced USCs underwent osteogenic and adipogenic differentiation. When co-cultured with hepatic progenitor cells, about 10% of USCs underwent hepatic differentiation. The ALT and AST levels of the USC-transplanted group were lower than that of the chronic liver-injury model group, and there were no significant differences between the two USC-transplanted groups. However, hepatocyte degeneration and liver fibrosis substantially improved in the hypoxia-pretreated USC-transplanted group compared with the normoxia USC-transplanted group. Taken together, USCs display desirable proliferation and differentiation characteristics, and USC transplantation partially improves abnormal liver function and pathology associated with chronic liver injury. Furthermore, hypoxia pretreatment promotes cell proliferation, migration, and colony formation by inducing autophagy, leading to USC-elicited liver tissue recovery following injury in vivo.