Background: Cold storage (CS) of cadaveric kidneys procured from hemodynamically stable donors for less than 24 hours is a safe procedure. Some papers indicate that continuous pulsatile machine perfusion (MP) allows for extension of preservation times, permits a wider use of kidneys damaged by preagonal ischemia, results in superior immediate function rate as compared to CS and improves long-term graft survival. The aim of the study was to evaluate the influence of kidney preservation method prior to transplantation on the characteristics of histopathological lesions of allografts at long-term post transplantation.
Material/Methods: The study group consisted of 274 patients who received a cadaveric kidney allograft between 1994 and 1999. Altogether 553 biopsy specimens were obtained from this group of patients between 1994 and 2004and graded according to Banff 2005 criteria.Two groups were identified: CS - recipients of kidneys stored in simple hypothermia (n=114) and MP - recipients of kidneys stored by machine perfusion (n=160). There were 161 cadaveric donors, 92 in the Mp group and 69 in the CS group. The 553 biopsy specimens obtained revealed the following: interstitial fibrosis and tubular atrophy - 189, chronic rejection - 19, acute rejection - 64, arteriosclerosis - 117, calcineurin inhibitor toxicity - 25, microangiopathy - 44, focal glomerulosclerosis - 82, arteriole hyalinization - 85, ATN - 241.
Results: In the CS group histopathological lesions consistent with interstitial fibrosis and tubular atrophy were more frequently encountered than in the MP group (90% vs 64%, p<0.05) Also, chronic rejection was more frequent in the CS group (9% vs 3%, p<0.05). The remaining lesions encountered in biopsies did not differ significantly between the groups.
Conclusions: Kidneys preserved by cold storage are more frequently affected by chronic rejection and interstitial fibrosis.

Keywords: long term results, Machine Perfusion, chronic rejection, histopathologic changes