A temporary inhibitor of a p53 gene for use in prophylaxis of ischemic reperfusion injury in a kidney at risk of IRI from a donor aged 35 years or older, wherein the inhibitor is for contacting the kidney, wherein contacting the kidney with the temporary inhibitor comprises administering the temporary inhibitor to a subject to which the kidney at risk of IRI has been transplanted, or contacting the kidney with the temporary inhibitor ex vivo prior to transplantation of the kidney to a recipient, wherein the inhibitor is a synthetic small interfering ribonucleic acid (siRNA) having the structure: 5' UGAAGGGUGAAAUAUUCUC 3' (antisense strand) (SEQ ID NO: 37) 3' ACUUCCCACUUUAUAAGAG 5' (sense strand) (SEQ ID NO: 36) wherein each of A, C, U and G is a ribonucleotide and each consecutive ribonucleotide is joined to the next ribonucleotide by a covalent bond; and wherein alternating ribonucleotides in both the antisense strand and the sense strand are 2'-O-methyl sugar modified ribonucleotides and a 2'-O-methyl sugar modified ribonucleotide is present at both the 5' terminus and the 3' terminus of the antisense strand and an unmodified ribonucleotide is present at both the 5' terminus and the 3' terminus of the sense strand; or wherein the inhibitor is a double-stranded ribonucleic acid (dsRNA) selected from: dsRNA Compound Sense (N')y 5->3 Antisense x 5->3 TP53_13_S2275 C3- C AGACCUAUGGAAAC U A C U-C3-pi 5' phos-AG U AGUuUCC A U A GGUC U G-C3;C3-pi TP53_13_S2276 C3- C AGACCUAUGGAAAC U A C U-C3-pi 5' phos-AG U AGUuU C C A U A GGUC U G-C3;C3-pi TP53_13_S2277 C3- C AGACCUAUGGAAAcuacu-C3-pi 5' phos-AG U AGUuUCC A UAGGUC U G-C3;C3-pi TP53_13_S2278 C3- C AGACCUAUGGAAAcuacu-C3-pi 5' phos-AG U AGUuU C C A U A GGUC U G-C3;C3-pi TP53_41_S709 GACUCAGACUGACAUUCUU-dTdT$ AAGAAUGUCAGUCUGAGUC-dTdT$ TP53_41_S2279 C3-GACUCAGACUGA C AU U C U U-C3-pi 5' phos-AAGAA U gU C AGUCU G AG U C-C3;C3-pi TP53_41_S2298 C3-GACUCAGACUGACAuucuu-C3-pi 5' phos-AAGAA U gU C AGUCU G AG U C-C3;C3-pi TP53_41_S2299 C3-GACUCAGACUGACAuucuu-C3-pi 5'phos-AAGAAUgU C AGUCUGAGUC-C3; C3-pi TP53_41_S2300 C3-GACUCAGACUGA C AU U C U U-C3-pi 5' phos-AAGAAUgU C AGUCUGAGUC-C3;C3-pi TP53_44_S2301 C3-GGGCCUGACUCAGAcugau-C3-pi 5' phos-AU C AGUc U GAGU C AGGCCC-C3;C3-pi TP53_44_S2302 C3-GGGCCUGACUCAGAcugau-C3-pi 5' phos-AU C AGUcUGAGUCAGGCCC-C3;C3-pi TP53_44_S2303 C3-GGGCCUGACUCAGAC U GAU-C3-pi 5' phos-AU C AGUc U GAGU C AGGCCC-C3;C3-pi TP53_44_S2304 C3-GGGCCUGACUCAGAC U GAU-C3-pi 5' phos-AU C AGUcUGAGUCAGGCCC-C3;C3-pi wherein: A, U, G, C - designates an unmodified ribonucleotide; A, U, G, C - designates a 2'-O-methyl sugar modified ribonucleotide; a, u, c, g - designates a nucleotide joined to an adjacent nucleotide (5'>3') by a 2'-5' internucleotide phosphate bond; C3 - designates 1,3-Propanediol, mono(dihydrogen phosphate) also identified as 3-Hydroxypropane-1-phosphate capping moiety [CAS RN: 13507-42-1]; C3C3 - designates a capping moiety consisting of two consecutive C3 molecules; dT - designates thymidine; dT$ - designates thymidine with no terminal phosphate; pi - designates 3'- phosphate; 5'-phos - designates 5'- phosphate. 5' UGAAGGGUGAAAUAUUCUC 3' (antisense strand) (SEQ ID NO: 37) 3' ACUUCCCACUUUAUAAGAG 5' (sense strand) (SEQ ID NO: 36) wherein each of A, C, U and G is a ribonucleotide and each consecutive ribonucleotide is joined to the next ribonucleotide by a covalent bond; and A, U, G, C - designates an unmodified ribonucleotide; A, U, G, C - designates a 2'-O-methyl sugar modified ribonucleotide; a, u, c, g - designates a nucleotide joined to an adjacent nucleotide (5'>3') by a 2'-5' internucleotide phosphate bond; C3 - designates 1,3-Propanediol, mono(dihydrogen phosphate) also identified as 3-Hydroxypropane-1-phosphate capping moiety [CAS RN: 13507-42-1]; C3C3 - designates a capping moiety consisting of two consecutive C3 molecules; dT - designates thymidine; dT$ - designates thymidine with no terminal phosphate; pi - designates 3'- phosphate; 5'-phos - designates 5'- phosphate.