Manganese Porphyrin Promotes Post Cardiac Arrest Recovery in Mice and Rats

Abstract

Introduction Cardiac arrest (CA) and resuscitation induces global cerebral ischemia and reperfusion, causing neurologic deficits or death. Manganese porphyrins, superoxide dismutase mimics, are reportedly able to effectively reduce ischemic injury in brain, kidney, and other tissues. This study evaluates the efficacy of a third generation lipophilic Mn porphyrin, MnTnBuOE-2-PyP5+, Mn(III) ortho meso-tetrakis (N-n-butoxyethylpyridinium-2-yl)porphyrin (MnBuOE, BMX-001), in both mouse and rat models of CA. Methods Forty-eight animals were subjected to 8 min of CA and resuscitated subsequently by chest compression and epinephrine infusion. Vehicle or MnBuOE was given immediately after resuscitation followed by daily subcutaneous injections. Body weight, spontaneous activity, neurologic deficits, rotarod performance, and neuronal death were assessed. Kidney tubular injury was assessed in CA mice. Data were collected by the investigators who were blinded to the treatment groups. Results Vehicle mice had a mortality of 20%, which was reduced by 50% by MnBuOE. All CA mice had body weight loss, spontaneous activity decline, neurologic deficits, and decreased rotarod performance that were significantly improved at three days post MnBuOE daily treatment. MnBuOE treatment reduced cortical neuronal death and kidney tubular injury in mice (p < 0.05) but not hippocampus neuronal death (23% MnBuOE vs. 34% vehicle group, p = 0.49). In rats, they had a better body-weight recovery and increased rotarod latency after MnBuOE treatment when compared to vehicle group (p < 0.01 vs. vehicle). MnBuOE-treated rats had a low percentage of hippocampus neuronal death (39% MnBuOE vs. 49% vehicle group, p = 0.21) and less tubular injury (p < 0.05) relative to vehicle group. Conclusions We demonstrated the ability of MnBuOE to improve post-CA survival, as well as functional outcomes in both mice and rats, which jointly account for the improvement not only of brain function but also of the overall wellbeing of the animals. While MnBuOE bears therapeutic potential for treating CA patients, the females and the animals with comorbidities must be further evaluated before advancing toward clinical trials.

Keywords: BMX-001; cardiac arrest; functional deficit; ischemia/reperfusion; manganese porphyrin; outcome.

Figure 1

Body weight and functional recovery in mouse that underwent CA. (A) Mouse survival curve. (B) Daily body weight changes, (C) Daily spontaneous activity time, (D) Spontaneous activity time on day 3 for individual mice. (E) Neuroscore at day 3 post CA. (F) Rotarod performance prior to and at day 3 post CA. Data were expressed as mean ± SEM except neuroscore (Bar = median). Each circle represents an individual mouse. Vehicle n = 8, MnBuOE n = 9 and sham n = 4. * p < 0.05 vs. vehicle. ** p < 0.01 vs. vehicle, *** p < 0.001 vs. Vehicle, # p < 0.05 vs. Sham.

Figure 2

Quantified post-CA histological damage in mice. (A) A representative hippocampal CA1 area in CA mice. Arrows point to dead neurons. (B) The percentage of CA1 neuronal death in both groups. (C) A representative cortex area in CA mice. Arrows point to dead neurons. (D) Cortex damage scores in both groups. (E) A representative kidney cortex. Arrow points to thinned tubular wall and enlarged tubular cavity. (F) Tubular injury score in both groups. Circles represent an individual mice and bars indicate mean ± SEM. * p < 0.05 vs. vehicle.

Figure 3

Arterial blood pressure changes in CA rats. Data were collected before CA, during CA, and 20 min after resuscitation in both groups. Data = mean ± SEM.

Figure 4

Body weight and neurologic recovery in rat which underwent CA. (A) Daily body weight change, (B) Neuroscore prior to CA, and at days 1 and 7 post-CA, (C) Rotarod performance prior to CA, and at days 1 and 7 post-CA. (D) Rotarod performances at day 7 for individual rats. Data were expressed as mean ± SEM except neuroscore. Each circle represents an individual rat. Bar = median. Vehicle n = 10 and MnBuOE n = 10. * p < 0.05 vs. vehicle, ** p < 0.01 vs. vehicle.

Figure 5

Left ventricular wall thickness at 7 days post-CA. (A) a representative left ventricular wall in vehicle rat, (B) a representative left ventricular wall in MnBuOE rat, (C) left ventricular wall thickness in vehicle (n = 5) and MnBuOE (n = 5). Data were expressed as mean ± SEM (lines in C). Each circle represents an individual rat.

Figure 6

Quantified post-CA histologic damage in rats. (A) A representative hippocampal CA1 area in CA rat. Arrows point to dead neurons. (B) The percentage of CA1 neuronal death in both groups. (C) A representative cortex area in CA rat. Arrows point to dead neurons. (D) Cortex damage scores in both groups. (E) A representative tubular ischemic injury in CA rat. Arrow points to thinned tubular wall and enlarged tubular cavity. (F) Tubular injury score in both groups. Circles represent individual animals and bars indicate mean ± SEM. * p < 0.05.