Senolytics May Improve Organ Transplantation
Senescent cells accumulate with age and negatively affect surrounding tissue with their pro-inflammatory secretions. Greater understanding of this contribution to degenerative aging has led to the development of senolytic therapies to selectively destroy these errant cells and thus improve tissue function. Cellular senescence may also occur in tissues undergoing transplantation, a result of the stresses involved, and cause loss of function and related issues following transplantation. Thus senolytics may find a use in the organ transplant industry as a way to improve success rates and patient outcomes following successful transplants.
Liver transplantation is the only curative option for patients with end-stage liver disease. Despite improvements in surgical techniques, nonanastomotic strictures (characterized by the progressive loss of biliary tract architecture) continue to occur after liver transplantation, negatively affecting liver function and frequently leading to graft loss and retransplantation. To study the biological effects of organ preservation before liver transplantation, we generated murine models that recapitulate liver procurement and static cold storage. In these models, we explored the response of cholangiocytes and hepatocytes to cold storage, focusing on responses that affect liver regeneration, including DNA damage, apoptosis, and cellular senescence.
We show that biliary senescence was induced during organ retrieval and exacerbated during static cold storage, resulting in impaired biliary regeneration. We identified decoy receptor 2 (DCR2)-dependent responses in cholangiocytes and hepatocytes, which differentially affected the outcome of those populations during cold storage. Moreover, CRISPR-mediated DCR2 knockdown in vitro increased cholangiocyte proliferation and decreased cellular senescence but had the opposite effect in hepatocytes. Using the p21 knockout model to inhibit senescence onset, we showed that biliary tract architecture was better preserved during cold storage. Similar results were achieved by administering senolytic ABT737 to mice before procurement.
Last, we perfused senolytics into discarded human donor livers and showed that biliary architecture and regenerative capacities were better preserved. Our results indicate that cholangiocytes are susceptible to senescence and identify the use of senolytics and the combination of senotherapies and machine-perfusion preservation to prevent this phenotype and reduce the incidence of biliary injury after transplantation.