Transdifferentiation of human male germline stem cells to hepatocytes in vivo via the transplantation under renal capsules

Here we proposed a new concept that human spermatogonial stem cells (SSCs) can transdifferentiate into hepatocytes in vivo. We first established liver injury model of mice by carbon tetrachloride to provide proper environment for human SSC transplantation. Liver mesenchymal cells were isolated from mice and identified phenotypically. Human SSC line was recombined with liver mesenchymal cells, and they were transplanted under renal capsules of nude mice with liver injury. The grafts expressed hepatocyte hallmarks, including ALB, AAT, CK18, and CYP1A2, whereas germ cell and SSC markers VASA and GPR125 were undetected in these cells, implicating that human SSCs were converted to hepatocytes. Furthermore, Western blots revealed high levels of PCNA, AFP, and ALB, indicating that human SSCs-derived hepatocytes had strong proliferation potential and features of hepatocytes. In addition, ALB-, CK8-, and CYP1A2- positive cells were detected in liver tissues of recipient mice. Significantly, no obvious lesion or teratomas was observed in several important organs and tissues of recipient mice, reflecting that transplantation of human SSCs was safe and feasible. Collectively, we have for the first time demonstrated that human SSCs can be transdifferentiated to hepatocyte in vivo. This study provides a novel approach for curing liver diseases using human SSC transplantation.