Host hepatocyte senescence determines the success of hepatocyte transplantation in a mouse model of liver injury

Background & Aims: Hepatocyte transplantation has shown promise for genetic diseases of the hepatocytes but to date has shown limited efficacy for non-genetic forms of severe liver injury. Limited cell engraftment and poor function of donor hepatocytes in recipient livers impacts the clinical utility of hepatocyte cell therapy. The mechanisms underpinning this are poorly understood. We explored this in a liver injury model, where predictable levels of injury and hepatocyte senescence were induced in AhCreMdm2 ^fl/fl mice through genetic excision of hepatocyte Mdm2. Methods: Freshly isolated mouse or human cryopreserved hepatocytes were delivered via intrasplenic injection into AhCreMdm2 ^fl/fl (immune competent and deficient strains) mice. Engraftment kinetics, donor cell engraftment and host liver function were assessed. Paired transcriptomic and proteomic analyses were performed on healthy vs. senescent mouse hepatocytes. Results: We found inhibition of host hepatocyte proliferation and liver injury is a requirement for donor hepatocyte engraftment and long-term repopulation, improving liver repair and function, but excessive senescence inhibited this process, causing a decline in graft function due to transmission of senescence from host to donor cells. Paired proteomic and transcriptomic analyses of healthy vs. senescent hepatocytes reveal a unique senescent signature associated with paracrine senescence. Modification of the host niche prior to transplantation with the senotherapeutic drug ABT737 improved donor cell proliferative capacity. Conclusions: The host niche impacts the initial engraftment and long-term function of transplanted hepatocytes. Targeting paracrine senescence may be a way to improve donor hepatocyte function, optimise therapy and guide translation into the clinic. Impact and Implications: Hepatocyte transplantation has shown promise for genetic diseases but has limited efficacy for acute and severe liver injury. Poor engraftment and functionality have prevented large-scale clinical application. We show that host senescence provides the required non-competitive niche for donor hepatocytes to repopulate the recipient liver, but can, paradoxically, negatively impact donor function. These findings demonstrate a requirement for a clear understanding of the host niche prior to cell transfusion. This has significant implications not only for hepatocellular therapies, but also when developing and optimising any preclinical and clinical cell therapies.