Ischemia/reperfusion injury (IRI), an inherent component of transplantation, affects organ quality and transplant outcomes. Although the complexity of the pathophysiology is recognized, detailed mechanisms remain unclear, and strategies preventing the consequences of IRI have been challenging. Of critical significance appears the link between IRI, the initiation of innate immune responses, and the (potential) augmentation of adaptive immunity. An improved understanding of those complex mechanisms and interactions may pave the way for more effective treatment strategies.

Consequences of aging are gaining clinical relevance. In transplantation, aging and immunosenescence impact treatment and outcomes. The impact of aging, however, will critically depend on distinguishing healthy, chronological aging from biological aging that may result into frailty. Approximately 15% of individuals older than 65 years are frail, and it is expected that this condition will gain more clinical relevance with an expected increase to greater than 20% over the next 5 years. Clearly, frailty impacts various general aspects of health care and organ transplantation in particular including patient selection, waitlist management and treatment after transplantation. In general, frailty has been characterized by a compromised physiological reserve and an augmented vulnerability. In comparison to healthy aging, inflammatory markers and cytokines are increased in frail older adults. Thus, modifications of the immune response, in addition to physical limitations and changes of metabolism, are likely to impact outcomes after transplantation. Here, we provide a risk assessment of frailty at the time of transplant evaluation and review effects on outcomes and recovery after transplantation. Moreover, we summarize our current understanding of the pathophysiology of frailty and consequences on immune responses and metabolism.