Placenta-targeted treatment with nMitoQ prevents an endothelin receptor-A pathway cardiac phenotype observed in adult male offspring exposed to hypoxia in utero.

Prenatal hypoxia is associated with enhanced susceptibility to cardiac ischemia-reperfusion (I/R) injury in adult offspring, however, the mechanisms remain to be fully investigated. Endothelin-1 (ET-1) is a vasoconstrictor that acts via endothelin A (ETA) and endothelin B (ETB) receptors and is essential in maintaining cardiovascular (CV) function. Prenatal hypoxia alters the ET-1 system in adult offspring possibly contributing to I/R susceptibility. We previously showed that ex vivo application of ETA antagonist ABT-627 during I/R prevented the recovery of cardiac function in prenatal hypoxia-exposed males but not in normoxic males nor normoxic or prenatal hypoxia-exposed females. In this follow-up study, we examined whether placenta-targeted treatment with a nanoparticle-encapsulated mitochondrial antioxidant (nMitoQ) during hypoxic pregnancies could alleviate this hypoxic phenotype observed in adult male offspring. We used a rat model of prenatal hypoxia where pregnant Sprague-Dawley rats were exposed to hypoxia (11% O2) from gestational days (GD) 15-21 after injection with 100 µL saline or nMitoQ (125 µM) on GD15. Male offspring were aged to 4 mo and ex vivo cardiac recovery from I/R was assessed. Offspring born from hypoxic pregnancies and treated with nMitoQ had increased cardiac recovery from I/R in the presence of ABT-627 compared with their untreated counterparts where ABT-627 prevented recovery. Cardiac ETA levels were increased in males born from hypoxic pregnancies with nMitoQ treatment compared with saline controls (Western blotting). Our data indicate a profound impact of placenta-targeted treatment to prevent an ETA receptor cardiac phenotype observed in adult male offspring exposed to hypoxia in utero.NEW & NOTEWORTHY In this follow-up study, we showed a complete lack of recovery from I/R injury after the application of an ETA receptor antagonist (ABT-627) in adult male offspring exposed to hypoxia in utero while maternal treatment with nMitoQ during prenatal hypoxia exposure prevented this effect. Our data suggest that nMitoQ treatment during hypoxic pregnancies may prevent a hypoxic cardiac phenotype in adult male offspring.

Sex-Specific Effects of Prenatal Hypoxia and a Placental Antioxidant Treatment on Cardiac Mitochondrial Function in the Young Adult Offspring.

Prenatal hypoxia is associated with placental oxidative stress, leading to impaired fetal growth and an increased risk of cardiovascular disease in the adult offspring; however, the mechanisms are unknown. Alterations in mitochondrial function may result in impaired cardiac function in offspring. In this study, we hypothesized that cardiac mitochondrial function is impaired in adult offspring exposed to intrauterine hypoxia, which can be prevented by placental treatment with a nanoparticle-encapsulated mitochondrial antioxidant (nMitoQ). Cardiac mitochondrial respiration was assessed in 4-month-old rat offspring exposed to prenatal hypoxia (11% O2) from gestational day (GD)15-21 receiving either saline or nMitoQ on GD 15. Prenatal hypoxia did not alter cardiac mitochondrial oxidative phosphorylation capacity in the male offspring. In females, the NADH + succinate pathway capacity decreased by prenatal hypoxia and tended to be increased by nMitoQ. Prenatal hypoxia also decreased the succinate pathway capacity in females. nMitoQ treatment increased respiratory coupling efficiency in prenatal hypoxia-exposed female offspring. In conclusion, prenatal hypoxia impaired cardiac mitochondrial function in adult female offspring only, which was improved with prenatal nMitoQ treatment. Therefore, treatment strategies targeting placental oxidative stress in prenatal hypoxia may reduce the risk of cardiovascular disease in adult offspring by improving cardiac mitochondrial function in a sex-specific manner.

Nanoparticle-encapsulated antioxidant improves placental mitochondrial function in a sexually dimorphic manner in a rat model of prenatal hypoxia.

Pregnancy complications associated with prenatal hypoxia lead to increased placental oxidative stress. Previous studies suggest that prenatal hypoxia can reduce mitochondrial respiratory capacity and mitochondrial fusion, which could lead to placental dysfunction and impaired fetal development. We developed a placenta-targeted treatment strategy using a mitochondrial antioxidant, MitoQ, encapsulated into nanoparticles (nMitoQ) to reduce placental oxidative stress and (indirectly) improve fetal outcomes. We hypothesized that, in a rat model of prenatal hypoxia, nMitoQ improves placental mitochondrial function and promotes mitochondrial fusion in both male and female placentae. Pregnant rats were treated with saline or nMitoQ on gestational day (GD) 15 and exposed to normoxia (21% O2 ) or hypoxia (11% O2 ) from GD15-21. On GD21, male and female placental labyrinth zones were collected for mitochondrial respirometry assessments, mitochondrial content, and markers of mitochondrial biogenesis, fusion and fission. Prenatal hypoxia reduced complex IV activity and fusion in male placentae, while nMitoQ improved complex IV activity in hypoxic male placentae. In female placentae, prenatal hypoxia decreased respiration through the S-pathway (complex II) and increased N-pathway (complex I) respiration, while nMitoQ increased fusion in hypoxic female placentae. No changes in mitochondrial content, biogenesis or fission were found. In conclusion, nMitoQ improved placental mitochondrial function in male and female placentae from fetuses exposed to prenatal hypoxia, which may contribute to improved placental function. However, the mechanisms (ie, changes in mitochondrial respiratory capacity and mitochondrial fusion) were distinct between the sexes. Treatment strategies targeted against placental oxidative stress could improve placental mitochondrial function in complicated pregnancies.

Placenta-targeted treatment in hypoxic dams improves maturation and growth of fetal cardiomyocytes in vitro via the release of placental factors.

NEW FINDINGS: What is the central question of this study? Does treatment of hypoxic dams with a placenta-targeted antioxidant prevent the release of placenta-derived factors that impair maturation or growth of fetal cardiomyocytes in vitro? What is the main finding and its importance? Factors released from hypoxic placentae impaired fetal cardiomyocyte maturation (induced terminal differentiation) and growth (increased cell size) in vitro, which was prevented by maternal treatment with a placenta-targeted antioxidant (nMitoQ). Moreover, there were no sex differences in the effects of placental factors on fetal cardiomyocyte maturation and growth. Overall, our data suggest that treatment targeted against placental oxidative stress could prevent fetal programming of cardiac diseases via the release of placental factors. ABSTRACT: Pregnancy complications associated with placental oxidative stress may impair fetal organ development through the release of placenta-derived factors into the fetal circulation. We assessed the effect of factors secreted from placentae previously exposed to prenatal hypoxia on fetal cardiomyocyte development and developed a treatment strategy that targets placental oxidative stress by encapsulating the antioxidant MitoQ into nanoparticles (nMitoQ). We used a rat model of prenatal hypoxia (gestational day (GD) 15-21), which was treated with saline or nMitoQ on GD15. On GD21, placentae were harvested, placed in culture, and conditioned medium (containing placenta-derived factors) was collected after 24 h. This conditioned medium was then added to cultured cardiomyocytes from control dam fetuses. Conditioned medium from prenatally hypoxic placentae increased the percentage of binucleated cardiomyocytes (marker of terminal differentiation) and the size of mononucleated and binucleated cardiomyocytes (sign of hypertrophy), effects that were prevented by nMitoQ treatment. Our data suggest that factors derived from placentae previously exposed to prenatal hypoxia lead to abnormal fetal cardiomyocyte development, and show that treatment against placental oxidative stress may prevent fetal programming of cardiac disease.

Sex-specific differences in the mechanisms for enhanced thromboxane A2-mediated vasoconstriction in adult offspring exposed to prenatal hypoxia.

BACKGROUND: Prenatal hypoxia, a common pregnancy complication, leads to impaired cardiovascular outcomes in the adult offspring. It results in impaired vasodilation in coronary and mesenteric arteries of the adult offspring, due to reduced nitric oxide (NO). Thromboxane A2 (TxA2) is a potent vasoconstrictor increased in cardiovascular diseases, but its role in the impact of prenatal hypoxia is unknown. To prevent the risk of cardiovascular disease by prenatal hypoxia, we have tested a maternal treatment using a nanoparticle-encapsulated mitochondrial antioxidant (nMitoQ). We hypothesized that prenatal hypoxia enhances vascular TxA2 responses in the adult offspring, due to decreased NO modulation, and that this might be prevented by maternal nMitoQ treatment. METHODS: Pregnant Sprague-Dawley rats received a single intravenous injection (100 µL) of vehicle (saline) or nMitoQ (125 µmol/L) on gestational day (GD)15 and were exposed to normoxia (21% O2) or hypoxia (11% O2) from GD15 to GD21 (term = 22 days). Coronary and mesenteric arteries were isolated from the 4-month-old female and male offspring, and vasoconstriction responses to U46619 (TxA2 analog) were evaluated using wire myography. In mesenteric arteries, L-NAME (pan-NO synthase (NOS) inhibitor) was used to assess NO modulation. Mesenteric artery endothelial (e)NOS, and TxA2 receptor expression, superoxide, and 3-nitrotyrosine levels were assessed by immunofluorescence. RESULTS: Prenatal hypoxia resulted in increased U46619 responsiveness in coronary and mesenteric arteries of the female offspring, and to a lesser extent in the male offspring, which was prevented by nMitoQ. In females, there was a reduced impact of L-NAME in mesenteric arteries of the prenatal hypoxia saline-treated females, and reduced 3-nitrotyrosine levels. In males, L-NAME increased U46619 responses in mesenteric artery to a similar extent, but TxA2 receptor expression was increased by prenatal hypoxia. There were no changes in eNOS or superoxide levels. CONCLUSIONS: Prenatal hypoxia increased TxA2 vasoconstrictor capacity in the adult offspring in a sex-specific manner, via reduced NO modulation in females and increased TP expression in males. Maternal placental antioxidant treatment prevented the impact of prenatal hypoxia. These findings increase our understanding of how complicated pregnancies can lead to a sex difference in the programming of cardiovascular disease in the adult offspring.

Prenatal hypoxia, when the fetus does not receive enough oxygen, is a common problem during pregnancy that impacts the developing fetus. It is associated with an increased risk of cardiovascular disease in the offspring in adulthood. While the mechanisms are not fully understood, the blood vessel function in the offspring may be impacted by prenatal hypoxia. We hypothesize that prenatal hypoxia increases the constriction of the blood vessels in the offspring. The placenta, an essential organ for fetal development, supplies oxygen and nutrients to the fetus. In prenatal hypoxia pregnancies, the placenta does not work properly. We have been studying a placental treatment (called nMitoQ) to improve placenta function and thereby the blood vessel function of the offspring. We used a rat model of prenatal hypoxia, where pregnant rats (dams) were placed in a low oxygen environment (hypoxia) during the last trimester of pregnancy. Control rats were kept in normal oxygen conditions. The dams were treated with nMitoQ, or with saline (control). Next, we studied the blood vessels of the offspring in adulthood. We found that prenatal hypoxia increases the constriction of the blood vessels, which was prevented by treating the dams with nMitoQ. Interestingly, this impact was more severe in females compared to males, and the mechanisms were different between the sexes. This study helps in the understanding of how complicated pregnancies can impair cardiovascular health in the offspring, and in a potential development of targeted and sex-specific therapies for those offspring at high risk for future cardiovascular disease.