Carrara C, Cravedi P, Perna A, Peraro F, Villa A, Carrara F, Cortinovis M, Gotti E, Plati AR, Amaduzzi A, Rota G, Lacanna F, Rossini G, Abelli M, Remuzzi G, Ruggenenti P: Preimplantation Histological Score Associates with 6-Month GFR in Recipients of Perfused, Older Kidney Grafts: Results from a Pilot Study. Nephron DOI 10.1159/000512341
The selection of donor kidneys for optimal post-transplant outcomes is an important issue, and discarding kidneys based on clinical criteria decreases the availability of organs. Pre-implantation biopsies of potential donor kidneys combined with pulsatile machine perfusion may help to improve marginal kidney donor use in transplantations.
Carrara and co-workers examined this issue in a single-center, prospective cohort study of 20 deceased donor kidney transplants for >60-year-old donors. The Kidney Donor Profile Index (KDPI) was >80% in 19 out of 20 cases. All grafts were hypothermically pulsatile machine perfused. A wedge biopsy was fixed in formalin and evaluated by a single pathologist. The global histological findings (glomeruli, tubule-interstitium, vascular) were scores on a scale of 0–12. Kidneys with a score of 0–4 were eligible for a single transplant, scores from 5 to 7 were eligible for a dual kidney transplant, and kidneys with a score of 8 or greater were discarded. Flow and resistance were monitored continuously during machine perfusion.
Ten kidneys were allocated to 10 recipients, 28 kidneys were allocated to 14 recipients, and 34 kidneys were discarded. Four recipients were not further evaluated. The average global histological score was 4.14 ± 1.4. Patient and graft survival at 6 months was 100% and delayed graft function was observed in 2 out of 20 patients. At 6 months, the eGFR was 41 mL/min among the recipients.
The machine perfusion duration averaged about 10 h and during perfusion vascular resistance was higher in those kidneys with a higher histological score, but it decreased similarly over time in both the high and low histological score groups. The global histological score was inversely correlated with eGFR at 6 months post-transplantation. The KDPI did not correlate with the 6-month eGFR.
Without the component of histologic evaluation, most of the kidneys included in this study would have been discarded, but the discard rate was only 47% in this study. Notably, the outcomes (at 6 months) were quite favorable in terms of graft function and survival. The optimal processing of biopsies using fixation and embedding may have contributed to these findings. The biopsy score was independently associated with an improvement of perfusion characteristics, and hypothermic, pulsatile perfusion might have contributed to better post-implantation function of the grafts. Although this was a small, pilot trial, it generates a hypothesis that deserves testing in a larger study with longer post-transplantation follow-up. Histological scoring and hypothermic, pulsatile perfusion might provide a new pathway for increasing donor availability.