Human Hepatocytes and Hematolymphoid Dual Reconstitution in Treosulfan-Conditioned uPA-NOG Mice

Abstract

Human-specific HIV-1 and hepatitis co-infections significantly affect patient management and call for new therapeutic options. Small xenotransplantation models with human hepatocytes and hematolymphoid tissue should facilitate antiviral/antiretroviral drug trials. However, experience with mouse strains tested for dual reconstitution is limited, with technical difficulties such as risky manipulations with newborns and high mortality rates due to metabolic abnormalities. The best animal strains for hepatocyte transplantation are not optimal for human hematopoietic stem cell (HSC) engraftment, and vice versa. We evaluated a new strain of highly immunodeficient nonobese diabetic/Shi-scid (severe combined immunodeficiency)/IL-2Rγc(null) (NOG) mice that carry two copies of the mouse albumin promoter-driven urokinase-type plasminogen activator transgene for dual reconstitution with human liver and immune cells. Three approaches for dual reconstitution were evaluated: i) freshly isolated fetal hepatoblasts were injected intrasplenically, followed by transplantation of cryopreserved HSCs obtained from the same tissue samples 1 month later after treosulfan conditioning; ii) treosulfan conditioning is followed by intrasplenic simultaneous transplantation of fetal hepatoblasts and HSCs; and iii) transplantation of mature hepatocytes is followed by mismatched HSCs. The long-term dual reconstitution was achieved on urokinase-type plasminogen activator-NOG mice with mature hepatocytes (not fetal hepatoblasts) and HSCs. Even major histocompatibility complex mismatched transplantation was sustained without any evidence of hepatocyte rejection by the human immune system.

Humanized mice efficiently engrafted with fetal hepatoblasts and syngeneic immune cells develop human monocytes and NK cells

“…This has recently been reported by transplanting adult human hepatocytes and mismatched HSC derived from fetal human liver tissue, which resulted in doubly engrafted animals [7,8]. However, to avoid allogeneic immune responses both grafts should be derived from the same human donor.…”

“…Human HSC can also be obtained from adults [9] but hepatocytes from these same individuals are rarely available. When fetal hepatoblasts are combined with syngeneic HSC the liver graft either was lost [7] or the engrafted hepatoblasts fail to expand to high levels [10,11]. Together, these findings suggest that allogeneic doubly reconstituted mice can be generated but that human fetal hepatoblasts insufficiently engraft human liver chimeric mice, which limits the generation of syngeneic doubly reconstituted mice.…”

Determinants of hepatitis B and delta virus host tropism

“…Engraftment efficiency appears to be strain-dependent as some studies report more robust engraftment with these fetal progenitor cells in AFC8 mice [25]. However, similar to liver transplantation in humans, close donor matching may not be imperative as it was recently shown that extensive humanization of both the liver and the immune system can been achieved through the use of allogeneic adult hepatocytes and HSCs without any overt rejection [34,35]. Dually engrafted mice mounted virus-specific immune responses following HBV infection, resulting in human-specific liver fibrosis [36].…”

Animal models for the study of HCV

“…However, studies on HCV immunopathogenesis, primary (human) adaptive immune response and vaccine efficacy in mice would require both a human liver graft and a functional (human) immune system in one and the same recipient animal. This has recently been achieved by combining adult human hepatocytes and human CD34 + hematopoietic stem cells (HSCs) from different human donors [110,111]. Although the authors did not show HCV infection, the high human engraftment levels suggest that these mice could become viremic upon HCV challenge.…”