Bone marrow-derived c-kit+ cells attenuate neonatal hyperoxia-induced lung injury.

Recent studies suggest that bone marrow (BM)-derived stem cells have therapeutic efficacy in neonatal hyperoxia-induced lung injury (HILI). c-kit, a tyrosine kinase receptor that regulates angiogenesis, is expressed on several populations of BM-derived cells. Preterm infants exposed to hyperoxia have decreased lung angiogenesis. Here we tested the hypothesis that administration of BM-derived c-kit(+) cells would improve angiogenesis in neonatal rats with HILI. To determine whether intratracheal (IT) administration of BM-derived c-kit(+) cells attenuates neonatal HILI, rat pups exposed to either normobaric normoxia (21% O2) or hyperoxia (90% O2) from postnatal day (P) 2 to P15 were randomly assigned to receive either IT BM-derived green fluorescent protein (GFP)(+) c-kit(-) cells (PL) or BM-derived GFP(+) c-kit(+) cells on P8. The effect of cell therapy on lung angiogenesis, alveolarization, pulmonary hypertension, vascular remodeling, cell proliferation, and apoptosis was determined at P15. Cell engraftment was determined by GFP immunostaining. Compared to PL, the IT administration of BM-derived c-kit(+) cells to neonatal rodents with HILI improved alveolarization as evidenced by increased lung septation and decreased mean linear intercept. This was accompanied by an increase in lung vascular density, a decrease in lung apoptosis, and an increase in the secretion of proangiogenic factors. There was no difference in pulmonary vascular remodeling or the degree of pulmonary hypertension. Confocal microscopy demonstrated that 1% of total lung cells were GFP(+) cells. IT administration of BM-derived c-kit(+) cells improves lung alveolarization and angiogenesis in neonatal HILI, and this may be secondary to an improvement in the lung angiogenic milieu.

Effects of maternal exposure to phthalates and bisphenol A during pregnancy on gestational age.

OBJECTIVE: Phthalates and bisphenol A (BPA) are ubiquitous environmental toxicants, present in high concentrations in numerous consumer products. We hypothesized that maternal exposure to phthalates and BPA in pregnancy is associated with shortened gestation. METHODS: Urinary phthalate and BPA metabolites from 72 pregnant women were measured at the last obstetric clinic visit prior to delivery. Using linear regression models, we estimated the change in gestational age associated with each interquartile range (IQR) increase in phthalate and BPA metabolite concentration. RESULTS: IQR increases in urinary mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and BPA concentrations were associated with 4.2 and 1.1 d decreases in gestation, respectively. When stratified by gender, these alterations were found only in male infants. CONCLUSIONS: We conclude that MEHHP and BPA (free + glucuronide) are associated with reductions in gestation, with effects observed only in males. Our findings are consistent with the idea that these agents induce gender-specific alterations in signaling via PPAR-γ transcription factor, androgen precursors and/or inflammatory mediators during the initiation of labor.

Stem cell factor improves lung recovery in rats following neonatal hyperoxia-induced lung injury.

BACKGROUND: Stem cell factor (SCF) and its receptor, c-kit, are modulators of angiogenesis. Neonatal hyperoxia-induced lung injury (HILI) is characterized by disordered angiogenesis. The objective of this study was to determine whether exogenous SCF improves recovery from neonatal HILI by improving angiogenesis. METHODS: Newborn rats assigned to normoxia (RA: 20.9% O2) or hyperoxia (90% O2) from postnatal day (P) 2 to 15, received daily injections of SCF 100 µg/kg or placebo (PL) from P15 to P21. Lung morphometry was performed at P28. Capillary tube formation in SCF-treated hyperoxia-exposed pulmonary microvascular endothelial cells (HPMECs) was determined by Matrigel assay. RESULTS: As compared with RA, hyperoxic-PL pups had decrease in alveolarization and in lung vascular density, and this was associated with increased right ventricular systolic pressure (RVSP), right ventricular hypertrophy, and vascular remodeling. In contrast, SCF-treated hyperoxic pups had increased angiogenesis, improved alveolarization, and attenuation of pulmonary hypertension as evidenced by decreased RVSP, right ventricular hypertrophy, and vascular remodeling. Moreover, in an in vitro model, SCF increased capillary tube formation in hyperoxia-exposed HPMECs. CONCLUSION: Exogenous SCF restores alveolar and vascular structure in neonatal rats with HILI by promoting neoangiogenesis. These findings suggest a new strategy to treat lung diseases characterized by dysangiogenesis.