Attenuating Ischemia and Reperfusion Injury Using NAD⁺-Loaded Nanoparticles in Mouse Kidneys

Ischemia and reperfusion (IR) injury is a major complication in solid organ transplantation, necessitating new therapeutic strategies to suppress IR injury and thereby reduce early allograft dysfunction and delayed graft function. In kidney transplantation, IR injury is associated with disruption of mitochondrial homeostasis, including depletion of nicotinamide adenine dinucleotide (NAD⁺) leading to diminished ATP levels, which cells need for survival. Here, we describe a novel approach to attenuate IR injury in a mouse kidney model using a NAD⁺-loaded nanoparticle, capable of direct intracellular delivery of NAD⁺.

C57BL/6NCrl mice underwent a laparotomy and occlusion of the left renal pedicle for 30 min to induce IR injury. Right nephrectomy was performed during the injury incubation. Mice received the test agents by 2 different techniques: direct kidney injection via the renal artery and systemically via intravenous (IV) injection into the vena cava. Mice received a single dose of the NAD⁺-loaded nanoparticle at 3 different concentrations. Blood and kidney tissue were collected for analysis 24 h after IR injury. Measurement of blood creatinine levels and histological analysis was performed to assess the protective effectiveness of the NAD⁺-loaded nanoparticle.

A single dose of NAD⁺-loaded nanoparticles resulted in significantly reduced creatinine levels in both the direct kidney-injected animals (P < 0.0001) and the IV-injected animals (P < 0.01) compared with empty nanoparticle, free NAD⁺, or saline controls. IR-induced renal tubular injury scores were markedly reduced for both IV delivery (P < 0.01) and direct injection (P < 0.05) compared with control treatments.

These results justify further development of this novel NAD⁺-loaded nanoparticle in the realm of organ transplantation to ameliorate IR injury and potentially increase usage of expanded criteria organs and reduce instances of delayed graft function.