Risk factors of metabolic bone disease of prematurity

To identify the factors that increase risk of metabolic bone disease of prematurity (MBD). A retrospective case-control study of infants born between January 2013–April 2014 with gestation age <30weeks and birth weight <1000g. MBD was defined as serum alkaline phosphatase above 500U/L and characteristic radiographic changes. Information was obtained on the presence of specific comorbidities. Of 76 infants evaluated, 40 met criteria for MBD. Median gestational age was 25weeks in both groups (p=0.512). Median birth weight of infants with MBD was significantly lower than that of controls (560 vs. 765g, p<0.01). Longer period of parenteral nutrition and dexamethasone use was observed in MBD group. Cholestasis was associated with the highest likelihood of MBD (OR 16.6, 95% CI 4.8–56.9). Seizures (OR 5.2, 95% CI 1.3–20.5) and the prolonged use of diuretics (OR 2.6, 95% CI 1.0–7.0) also significantly increased the likelihood of MBD. Only cholestasis remained significant (OR 9.6, 95% CI 2.1–45.3) after multiple regression analysis. Cholestasis is a significant risk factor for the development of MBD. Our future studies will be directed towards determining the causal relationship between cholestasis and MBD. •Metabolic Bone Disease (MBD) is a common problem among preterm infants•Cholestasis carries the highest likelihood of developing likelihood of developing MBD•Lower birth weight, longer duration of parenteral nutrition and steroid use are also observed in preterm infants with MB

The Effect of Gender on Mesenchymal Stem Cell (MSC) Efficacy in Neonatal Hyperoxia-Induced Lung Injury.

Mesenchymal stem cells (MSC) improve alveolar and vascular structures in experimental models of bronchopulmonary dysplasia (BPD). Female MSC secrete more anti-inflammatory and pro-angiogenic factors as compared to male MSC. Whether the therapeutic efficacy of MSC in attenuating lung injury in an experimental model of BPD is influenced by the sex of the donor MSC or recipient is unknown. Here we tested the hypothesis that female MSC would have greater lung regenerative properties than male MSC in experimental BPD and this benefit would be more evident in males.To determine whether intra-tracheal (IT) administration of female MSC to neonatal rats with experimental BPD has more beneficial reparative effects as compared to IT male MSC.Newborn Sprague-Dawley rats exposed to normoxia (RA) or hyperoxia (85% O2) from postnatal day (P) 2- P21 were randomly assigned to receive male or female IT bone marrow (BM)-derived green fluorescent protein (GFP+) MSC (1 x 106 cells/50 μl), or Placebo on P7. Pulmonary hypertension (PH), vascular remodeling, alveolarization, and angiogenesis were assessed at P21. PH was determined by measuring right ventricular systolic pressure (RVSP) and pulmonary vascular remodeling was evaluated by quantifying the percentage of muscularized peripheral pulmonary vessels. Alveolarization was evaluated by measuring mean linear intercept (MLI) and radial alveolar count (RAC). Angiogenesis was determined by measuring vascular density. Data are expressed as mean ± SD, and analyzed by ANOVA.There were no significant differences in the RA groups. Exposure to hyperoxia resulted in a decrease in vascular density and RAC, with a significant increase in MLI, RVSP, and the percentage of partially and fully muscularized pulmonary arterioles. Administration of both male and female MSC significantly improved vascular density, alveolarization, RVSP, percent of muscularized vessels and alveolarization. Interestingly, the improvement in PH and vascular remodeling was more robust in the hyperoxic rodents who received MSC from female donors. In keeping with our hypothesis, male animals receiving female MSC, had a greater improvement in vascular remodeling. This was accompanied by a more significant decrease in lung pro-inflammatory markers and a larger increase in anti-inflammatory and pro-angiogenic markers in male rodents that received female MSC. There were no significant differences in MSC engraftment among groups.Female BM-derived MSC have greater therapeutic efficacy than male MSC in reducing neonatal hyperoxia-induced lung inflammation and vascular remodeling. Furthermore, the beneficial effects of female MSC were more pronounced in male animals. Together, these findings suggest that female MSC maybe the most potent BM-derived MSC population for lung repair in severe BPD complicated by PH

Female MSC have more marked effects on pulmonary hypertension.

<p>(a) Female MSC improve right ventricular systolic pressure (RVSP) to a greater degree than male MSC. The efficacy of MSC in improving RVSP in female (b) and male (c) animals is not dependent on the sex of the recipient. (*<i>P</i> < 0.05: RA vs hyperoxia-PL; † <i>P</i> <0.05: hyperoxia-PL vs hyperoxia male or female MSC; $ <i>P</i> <0.05: hyperoxia male MSC vs hyperoxia female MSC). White bars are RA and black bars are hyperoxia.</p

Female MSC exhibit greater anti-remodeling effects.

<p>(a) Lung sections stained with Von Willebrand Factor (green), α-smooth muscle actin (red), and DAPI (blue), demonstrating improved vascular remodeling in hyperoxia-exposed pups treated with male or female MSC. Original magnification X400. (b) Female MSC are superior to male MSC in reducing the percentage of fully muscularized blood vessels. (c) IT male or female MSC improved medial wall thickness of vessels (20–50 μm). In female pups, IT male or female MSC similarly improve the percentage of muscularized vessels (d), and the medial wall thickness (e). In male pups, IT female MSC are superior to male MSC in improving the percentage of muscularized blood vessels (f), while being as effective in reducing the medial wall thickness (g). (*<i>P</i> < 0.05: RA vs hyperoxia-PL; † hyperoxia-PL vs hyperoxia male or female MSC; $ <i>P</i> <0.05: hyperoxia male MSC vs hyperoxia female MSC). White bars are RA and black bars are hyperoxia unless otherwise specified.</p

Intra-tracheal (IT) administration of male or female MSC similarly improves alveolarization.

<p>(a) Hematoxylin and eosin stained lung sections demonstrating improved alveolar structure in hyperoxia-exposed pups treated with IT male or female MSC. Original magnification X 200. Bars = 100 μm. IT male or female MSC similarly increased mean linear intercept (b) and decreased radial alveolar count (c). IT male or female MSC similarly improve RAC in female (d) and male (e) animals. (*<i>P</i> < 0.05; Room air (RA) vs hyperoxia- placebo (PL), † <i>P</i> <0.05; hyperoxia -PL vs hyperoxia male or female MSC). White bars are RA and black bars are hyperoxia.</p

Female MSC produce more VEGF and IL-10 after 24 hours in culture.

<p>(a) VEGF concentration as measured by ELISA in male and female MSC (b) IL-10 concentration as measured by ELISA in male and female MSC (* <i>P</i> < 0.05; Male vs Female MSC, N = 3 experiments/group).</p

IT male or female MSC similarly improve lung angiogenesis.

<p>(a) Lung sections stained with Von Willebrand Factor (green) and 4’6-diamidino-2-phenylindole (DAPI: blue), demonstrating improved vascular density in hyperoxia-exposed pups treated with male and female MSC at P7. Original magnification X 100. Bars = 100 μm. (b) IT male and female MSC similarly increased lung vascular density in hyperoxic pups. (c) Female MSC normalizes lung VEGF concentration in hyperoxia. Female and male MSC exhibit similar efficacy in improving lung angiogenesis in female (d) and male (e) animals. (*<i>P</i> < 0.05: RA vs hyperoxia-PL; † <i>P</i> <0.05: hyperoxia-PL vs hyperoxia male or female MSC; $ <i>P</i> <0.05: hyperoxia male MSC vs hyperoxia female MSC). White bars are RA and black bars are hyperoxia.</p

Neonatal intermittent hypoxia persistently impairs lung vascular development and induces long-term lung mitochondrial DNA damage

Adults born preterm have an increased risk of pulmonary vascular disease. Extreme preterm infants often require supplemental oxygen but they also exhibit frequent intermittent hypoxemic episodes (IH). Here, we test the hypothesis that neonatal IH induces lung endothelial cell mitochondrial DNA (mitDNA) damage and contributes to long-term pulmonary vascular disease and pulmonary hypertension (PH). Newborn C57BL/6J mice were assigned to the following groups:) normoxia,) hyperoxia (O65%),) normoxia cycling with IH (O21% + O10%), and) hyperoxia cycling with IH (O65% + O10%) for 3 wk. IH episodes were initiated on. Lung angiogenesis, PH, and mitDNA lesions were assessed at 3 wk and 3 mo. In vitro, the effect of IH on tubule formation and mitDNA lesions was evaluated in human pulmonary microvascular endothelial cells (HPMECs). Data were analyzed by ANOVA. In vitro, IH exposure reduced tubule formation and increased mitDNA lesions in HPMECs. This was most marked in HPMECs exposed to hyperoxia cycling with IH. In vivo, neonatal IH increased lung mitDNA lesions, impaired angiogenesis, and induced PH in 3-wk-old mice. These findings were pronounced in mice exposed to hyperoxia cycling with IH. At 3 mo follow-up, mice exposed to neonatal IH had persistently increased lung mitDNA lesions and impaired lung angiogenesis, even without concomitant hyperoxia exposure. Neonatal IH induces lung endothelial cell mitDNA damage and causes persistent impairment in lung angiogenesis. These findings provide important mechanistic insight into the pathogenesis of pulmonary vascular disease in preterm survivors.Our current study demonstrates that neonatal intermittent hypoxia (IH) alters lung endothelial cell function, induces mitochondrial DNA lesions, and impairs lung vascular growth into adulthood. Moreover, when superimposed on hyperoxia, neonatal IH induces a severe lung vascular phenotype that is seen in preterm infants with PH. These findings suggest that neonatal IH contributes to PH in adults born preterm and importantly, that mitochondrial protection strategies may mitigate these deleterious effects

Neonatal hyperoxia exposure induces aortic biomechanical alterations and cardiac dysfunction in juvenile rats

Supplemental oxygen (O ) therapy in preterm infants impairs lung development, but the impact of O on long-term systemic vascular structure and function has not been well-explored. The present study tested the hypothesis that neonatal O therapy induces long-term structural and functional alterations in the systemic vasculature, resulting in vascular stiffness observed in children and young adults born preterm. Newborn Sprague-Dawley rats were exposed to normoxia (21% O ) or hyperoxia (85% O ) for 1 and 3 weeks. A subgroup exposed to 3 weeks hyperoxia was recovered in normoxia for an additional 3 weeks. Aortic stiffness was assessed by pulse wave velocity (PWV) using Doppler ultrasound and pressure myography. Aorta remodeling was assessed by collagen deposition and expression. Left ventricular (LV) function was assessed by echocardiography. We found that neonatal hyperoxia exposure increased vascular stiffness at 3 weeks, which persisted after normoxic recovery at 6 weeks of age. These findings were accompanied by increased PWV, aortic remodeling, and altered LV function as evidenced by decreased ejection fraction, cardiac output, and stroke volume. Importantly, these functional changes were associated with increased collagen deposition in the aorta. Together, these findings demonstrate that neonatal hyperoxia induces early and sustained biomechanical alterations in the systemic vasculature and impairs LV function. Early identification of preterm infants who are at risk of developing systemic vascular dysfunction will be crucial in developing targeted prevention strategies that may improve the long-term cardiovascular outcomes in this vulnerable population