Machine perfusion of kidneys from brain-dead donors better protects against delayed graft function after transplantation compared with therapeutic hypothermia, according to new trial findings published in the New England Journal of Medicine.

In the randomized trial, the risk for delayed graft function was a significant 1.7-fold higher after hypothermia compared with machine perfusion, Claus Niemann, MD, of the University of California San Francisco, and colleagues reported. The risk for dialysis initiation within the first 7 days of transplantation was a significant 1.6-fold higher after hypothermia compared with combination therapy.

Graft survival at 1 year was similar across the 3 groups, the investigators reported.

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Adult brain-dead donors in the mild hypothermia group were externally cooled to 34-35°C with kidney perfusion. The machine perfusion group had donor normothermia, followed by ex situ hypothermic, nonoxygenated machine perfusion of the kidneys. The combination group had donor hypothermia and machine perfusion of a kidney.

Among 725 adult brain-dead donors, 1349 kidneys were transplanted, including 359 kidneys in the hypothermia group, 511 in the machine-perfusion group, and 479 in the combined-therapy group. Delayed graft function occurred in a lower proportion of the machine perfusion than hypothermia or combined-therapy groups (19% vs 30% vs 22%).

“Our findings provide additional evidence that machine perfusion protects against delayed graft function as compared with static cold storage, even when the donor was undergoing therapeutic hypothermia,” Dr Niemann’s team wrote.

In an accompanying editorial, Paulo Martins, MD, PhD, of the University of Massachusetts in Worcester, and Winfred Williams, MD, of Massachusetts General Hospital in Boston, noted that this trial did not include a control group representing current standard practice consisting of donor normothermia and cold static preservation alone. “Therefore, a head-to-head comparison of current-day, standard protocols for procurement and preservation is not possible,” they stated.

Disclosure: This research was supported by Arnold Ventures. Please see the original reference for a full list of disclosures.


Malinoski D, Saunders C, Swain S, et al. Hypothermia or machine perfusion in kidney donors. N Engl J Med 388(5):418-426. Published online February 2, 2023. doi:10.1056/NEJMoa2118265

Martins PN, Williams WW. To cool or not to cool – organ-preservation strategies in transplantation. N Engl J Med 388(5):468-469. Published online February 2, 2023. doi:10.1056/NEJMe2214715