Fatty acid metabolism during hypothermic perfusion of the isolated dog kidney

Current Insights into the Metabolome during Hypothermic Kidney Perfusion-A Scoping Review

This scoping review summarizes what is known about kidney metabolism during hypothermic perfusion preservation. Papers studying kidney metabolism during hypothermic (<12 °C) perfusion were identified (PubMed, Embase, Web of Science, Cochrane). Out of 14,335 initially identified records, 52 were included [dog (26/52), rabbit (2/52), pig (20/52), human (7/52)]. These were published between 1970-2023, partially explaining study heterogeneity. There is a considerable risk of bias in the reported studies. Studies used different perfusates, oxygenation levels, kidney injury levels, and devices and reported on perfusate and tissue metabolites. In 11 papers, (non)radioactively labeled metabolites (tracers) were used to study metabolic pathways. Together these studies show that kidneys are metabolically active during hypothermic perfusion, regardless of the perfusion setting. Although tracers give us more insight into active metabolic pathways, kidney metabolism during hypothermic perfusion is incompletely understood. Metabolism is influenced by perfusate composition, oxygenation levels, and likely also by pre-existing ischemic injury. In the modern era, with increasing donations after circulatory death and the emergence of hypothermic oxygenated perfusion, the focus should be on understanding metabolic perturbations caused by pre-existing injury levels and the effect of perfusate oxygen levels. The use of tracers is indispensable to understanding the kidney's metabolism during perfusion, given the complexity of interactions between different metabolites.

NOS: the underlying mechanism preserving vascular integrity and during ex vivo warm kidney perfusion

Research involving metabolically active and functioning organs, maintained ex vivo in culture-like conditions, could provide numerous opportunities for medical innovations and research. We report successful perfusion of isolated canine and human kidneys ex vivo at near physiologic temperature for 48 h. During the perfusions parameters of metabolism and function remained stable. Nitric oxide synthase (NOS) was identified as the underlying mechanism preserving vascular integrity. Most importantly, when the canine kidneys were reimplanted there was immediate normal renal function. This report highlights the potential significance of whole organ culture using a warm temperature ex vivo perfusion and discusses medical applications that could be developed.