The influence of EPO and hypothermia on the kidneys of rats after perinatal asphyxia

Hypothermia cannot ameliorate renal fibrosis after asphyxia in the newborn piglet

BACKGROUND

The effects of therapeutic hypothermia (TH) on renal function are not widely reported, especially in longer term animal models. The hypothesis of this study was that TH of the kidneys of hypoxic-ischemic newborn piglets would reduce pathological renal fibrosis.

METHODS

Twenty-five newborn piglets obtained within 24 h of birth were classified into a control group (n = 5), an hypoxic insult with normothermia (HI-NT) group (n = 12), and an hypoxic insult with TH (HI-TH) group (33.5 °C ± 0.5 °C for 24 h; n = 8). Five days after the insult, all piglets were sacrificed under deep anesthesia by isoflurane inhalation. The kidneys were perfused with phosphate-buffered paraformaldehyde and immersed in formalin buffer. Territory fibrosis was studied and scored in the renal medulla using Azan staining.

RESULTS

Fibrosis area scores (means ± standard deviations) based on Azan staining were 1.00 ± 0.46 in the control group, 2.85 ± 0.93 in the HI-NT group, and 3.58 ± 1.14 in the HI-TH group. The fibrosis area of the HI-NT and HI-TH groups was larger than that of the control. The HI-NT and HI-TH groups were not statistically different.

CONCLUSIONS

Renal fibrosis is affected by perinatal asphyxia and cannot be prevented by TH, based on histopathological findings.

Bridging Translation by Improving Preclinical Study Design in AKI

Despite extensive research, no therapeutic interventions have been shown to prevent AKI, accelerate recovery of AKI, or reduce progression of AKI to CKD in patients. This failure in translation has led investigators to speculate that the animal models being used do not predict therapeutic responses in humans. Although this issue continues to be debated, an important concern that has not been addressed is whether improvements in preclinical study design can be identified that might also increase the likelihood of translating basic AKI research into clinical practice using the current models. In this review, we have taken an evidence-based approach to identify common weaknesses in study design and reporting in preclinical AKI research that may contribute to the poor translatability of the findings. We focused on use of N-acetylcysteine or sodium bicarbonate for the prevention of contrast-induced AKI and use of erythropoietin for the prevention of AKI, two therapeutic approaches that have been extensively studied in clinical trials. On the basis of our findings, we identified five areas for improvement in preclinical study design and reporting. These suggested and preliminary guidelines may help improve the quality of preclinical research for AKI drug development.

Ovine fetal renal development impacted by multiple fetuses and uterine space restriction

Intrauterine growth restriction (IUGR) from uteroplacental dysfunction causes impaired nephrogenesis and ultimately hypertension, but it is unknown whether IUGR caused by insufficient space for placental development seen in uterine anomalies and/or multifetal gestation exerts the same effects. Fetal renal development and metabolism were studied in an ovine space-restriction model by combining unilateral horn surgical ligation and/or multifetal gestation. Reduced placental attachment sites and placental weight per fetus defined space-restricted (USR) v. control nonrestricted (NSR) fetuses. Space-restricted fetuses exhibited evidence for decreased plasma volume, with higher hematocrit and plasma albumin at gestational day (GD) 120, followed by lower blood pO2, and higher osmolarity and creatinine at GD130, P < 0.05 for all. By combining treatments, fetal kidney weight relative to fetal weight was inversely related to both fetal weight and plasma creatinine levels, P < 0.05 for both. At GD130, space-restricted fetal kidney weights, cortical depths and glomerular generations were decreased, P < 0.05 for all. Space-restricted kidneys underwent an adaptive response by prolonging active nephrogenesis and increasing maculae densa number, P < 0.05 for both. The major renal adaptations in space-restricted IUGR fetuses included immaturity in both development and endocrine function, with evidence for impaired renal excretory function.

The effect of erythropoietin on the severity of retinopathy of prematurity

AIMS

Exogenous human erythropoietin (EPO) artificially synthesised through recombinant DNA technology (rHuEPO) is currently used as a substitute for blood transfusion in preterm and low birth weight neonates. The objective of this study is to determine whether the use of rHuEPO is associated with an increased severity of retinopathy of prematurity (ROP) in preterm neonates.

METHOD

This retrospective review studies neonates who were admitted to a tertiary perinatal unit and screened for ROP during the 10-year period from January 2003 to December 2012.

RESULTS

: During the 10-year period, 688 preterm neonates underwent ROP screening, with 198 identified as having ROP. The incidence of stage 1 ROP was 51.5% (102/198), followed by 35.9% (71/198) for stage 2, and 12.6% (25/198) for stage 3 and greater. Plus disease was seen in 14 neonates (7.1%). Treatment (laser photocoagulation) was administered in 64% of neonates (16/25) with stage 3 of the disease and above because of progression to threshold ROP. Twenty-six (13%) of the neonates received rHuEPO treatment. There were no statistically significant differences in birth weight (910.4 vs 885 g; P=0.71), gestational age (26.5 vs 25.8 weeks; P=0.09), and duration of ventilation (512 vs 501.4 h; P=0.92) between neonates who did not receive rHuEPO compared with those who were treated with rHuEPO. Multivariate regression analysis showed that the use of EPO was associated with increased severity of ROP.

CONCLUSIONS

EPO therapy appears to increase the risk of development and worsening of ROP.

Neuroprotective effects of hypothermia and erythropoietin after perinatal asphyxia in newborn rats

OBJECTIVE

Evaluation of neuroprotective effects of hypothermia, erythropoietin and their simultaneous use after perinatal asphyxia in newborn rats.

METHOD

Hysterectomy was performed to Wistar female rats on the last day of gestation. Perinatal asphyxia was induced by submersion of uterus containing pups in saline for 15 min. After resuscitation, pups were randomized into 4 groups, 15 animals in each: G1 - asphyxia; G2 - asphyxia + hypothermia (rectal temperature 33 °C for 1 h); G3 - asphyxia + erythropoietin (Darbepoetin-α 2.5 μg, intraperitoneally) and G4 - asphyxia + erythropoietin + hypothermia. Pups were sacrificed on 7th day of life and histopathological analysis of hippocampus was performed.

RESULTS

Measure of damage to dorsal, ventral and entire hippocampus was significantly lower in groups G2, G3 and G4 than in group G1 (p ~ 0.00; respectively). Measure of damage to hippocampus in group G4 was significantly lower than in group G2 (p = 0.029).

CONCLUSIONS

This study demonstrates that simultaneous use of hypothermia and erythropoietin has more expressed neuroprotective effects than sole use of hypothermia after perinatal asphyxia in newborn rats.