Graft assessment of the ex vivo perfused porcine kidney using hyperpolarized [1-¹³ C]pyruvate

Normothermic perfusion is an emerging strategy for donor organ preservation and therapy, incited by the high worldwide demand for organs for transplantation. Hyperpolarized MRI and MRS using [1-¹³ C]pyruvate and other ¹³ C-labeled molecules pose a novel way to acquire highly detailed information about metabolism and function in a noninvasive manner. This study investigates the use of this methodology as a means to study and monitor the state of ex vivo perfused porcine kidneys, in the context of kidney graft preservation research.

Kidneys from four 40-kg Danish domestic pigs were perfused ex vivo with whole blood under normothermic conditions, using an MR-compatible perfusion system. Kidneys were investigated using ¹ H MRI as well as hyperpolarized [1-¹³ C]pyruvate MRI and MRS. Using the acquired anatomical, functional and metabolic data, the state of the ex vivo perfused porcine kidney could be quantified.

Four kidneys were successfully perfused for 120 minutes and verified using a DCE perfusion experiment. Renal metabolism was examined using hyperpolarized [1-¹³ C]pyruvate MRI and MRS, and displayed an apparent reduction in pyruvate turnover compared with the usual case in vivo. Perfusion and blood gas parameters were in the normal ex vivo range.

This study demonstrates the ability to monitor ex vivo graft metabolism and function in a large animal model, resembling human renal physiology. The ability of hyperpolarized MRI and MRS to directly compare the metabolic state of an organ in vivo and ex vivo, in combination with the simple MR implementation of normothermic perfusion, renders this methodology a powerful future tool for graft preservation research.