Survival Benefit in Older Patients Transplanted With Viremic Hepatitis C Positive Kidneys When Compared With High KDPI Kidneys

Effect of Cellular Senescence in Disease Progression and Transplantation: Immune Cells and Solid Organs

Aging of the world population significantly impacts healthcare globally and specifically, the field of transplantation. Together with end-organ dysfunction and prolonged immunosuppression, age increases the frequency of comorbid chronic diseases in transplant candidates and recipients, contributing to inferior outcomes. Although the frequency of death increases with age, limited use of organs from older deceased donors reflects the concerns about organ durability and inadequate function. Cellular senescence (CS) is a hallmark of aging, which occurs in response to a myriad of cellular stressors, leading to activation of signaling cascades that stably arrest cell cycle progression to prevent tumorigenesis. In aging and chronic conditions, senescent cells accumulate as the immune system's ability to clear them wanes, which is causally implicated in the progression of chronic diseases, immune dysfunction, organ damage, decreased regenerative capacity, and aging itself. The intimate interplay between senescent cells, their proinflammatory secretome, and immune cells results in a positive feedback loop, propagating chronic sterile inflammation and the spread of CS. Hence, senescent cells in organs from older donors trigger the recipient's alloimmune response, resulting in the increased risk of graft loss. Eliminating senescent cells or attenuating their inflammatory phenotype is a novel, potential therapeutic target to improve transplant outcomes and expand utilization of organs from older donors. This review focuses on the current knowledge about the impact of CS on circulating immune cells in the context of organ damage and disease progression, discusses the impact of CS on abdominal solid organs that are commonly transplanted, and reviews emerging therapies that target CS.

Utilization of hepatitis C virus-positive donors in kidney transplantation

PURPOSE OF REVIEW

Direct-acting antivirals (DAA) have transformed kidney transplantation by increasing the donor pool from hepatitis C virus (HCV)-infected donors and allowing HCV nucleic acid amplification testing (NAT) donor-positive/recipient-negative (D+/R-) transplantation over the last 7 years. Willingness to accept kidneys from HCV-infected donors and timing/duration of DAA therapy have been evolving.

RECENT FINDINGS

By 2021, most of the HCV NAT+ kidneys (92.6%) were transplanted to HCV-naive recipients. Despite the availability of effective DAA therapy, the discard rate of HCV NAT kidneys has been stagnant around 25%. The proportion of wait-listed patients willing to accept a deceased donor kidney from HCV Ab+ and HCV NAT+ donors increased 20-fold between 2015 and 2022. Wait-listed time to receive HCV NAT+ kidneys has been rising and most of the kidneys are transplanted to HCV-naive recipients. The proportion of deceased donor kidney transplants performed in recipients with HCV seropositivity decreased from 5.1 to 2.8% during the same period. Relatively short courses of DAA therapy (7-8 days) appear to be effective to decrease HCV transmission (<5%) and achieve sustained virological response at 12 weeks if administered prior to revascularization.

SUMMARY

Further studies are needed to evaluate long-term outcomes of HCV NAT D+/R- transplantation and the best course of DAA treatment.