217 - Antenatal Vitamin D Therapy Improves Pulmonary Endothelial Cell Growth and Response to Proangiogenic Stimuli in a Preeclampsia Model of Bronchopulmonary Dysplasia

Poster Number: 217
Publication Number: 217.221

Michael Cookson, University of Colorado School of Medicine, Aurora, CO, United States; Tania Gonzalez, University of Colorado School of Medicine, Aurora, CO, United States; Elisa Bye, University of Colorado School of Medicine, Aurora, CO, United States; James Fleet, University of Texas at Austin, Austin, TX, United States; Steven Abman, University of Colorado School of Medicine, denver, CO, United States; Erica Mandell, University of Colorado School of Medicine, Aurora, CO, United States

Background: Preeclampsia (PE) is a major risk factor for preterm birth and the subsequent development of bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity. We have previously shown that antenatal (AN) exposure to soluble fms-like tyrosine kinase 1 (sFlt-1), an endogenous VEGF antagonist that is markedly increased in maternal blood and amniotic fluid in PE, causes abnormal lung structure and function in infant rats. We have also shown that AN vitamin D (VD; 1,25(OH)2D3) treatment improves infant lung structure and function after sFlt-1exposure in vivo. Since sFlt-1disrupts angiogenesis and VD has pro-angiogenic effects, we hypothesized that VD treatment improves lung structure through preserved pulmonary endothelial cell (PEC) growth after AN sFlt-1 exposure.
 

Objective: To determine if VD treatment preserves rat PEC growth in vitro after AN sFlt-1 exposure.

Design/Methods: Fetal rats were exposed to saline (CTL), recombinant human sFlt-1 (sFlt-1), sFlt-1 + VD, or VD, via intra-amniotic (IA) injection at E20 and delivered at E22. At birth, PEC were isolated using CD-31 immunomagnetic cell separation. In vitro growth assays were conducted to assess baseline growth and response to VD or VEGF.

Results: We found that AN exposure to sFlt-1 reduced PEC growth by 43% when compared to CTL PEC (p < .05). AN VD alone had no effect on PEC growth compared to CTL PEC, but when combined with sFlt-1exposure, VD prevented the suppression of PEC growth caused by sFlt-1alone (s-Flt-1 + VD v. s-Flt-1; p< 0.01) We next determined the effects of angiogenic stimuli on PEC growth. In CTL PEC, exogenous VEGF and 1,25(OH)2D3 increased PEC growth by 44 % and 33%, respectively, compared to non-stimulated CTL PEC (p < 0.05). In sFlt-1exposed PEC, VEGF and 1,25(OH)2D3 increased PEC growth by 70% and 68%, respectively, compared to non-stimulated sFlt-1 PEC (p < 0.01). In sFlt-1 + VD exposed PEC, VEGF and 1,25(OH)2D3 increased PEC growth by 68% and 55%, respectively, compared to non-stimulated sFlt-1 + VD (p < 0.05). In VD PEC, VEGF and 1,25(OH)2D3 increased PEC growth by 82% and 73% respectively compared to non-stimulated VD PEC (p < 0.01). In CTL PEC, VEGF increased growth by 50% compared to sFlt-1 PEC treated with VEGF (p < 0.01).Conclusion(s): AN sFlt-1 exposure reduced PEC growth and blunted responsiveness to exogenous angiogenic stimuli in vitro, and that AN VD treatment enhanced PEC growth and the response to angiogenic stimuli in this model. We speculate that VD treatment of sFlt-1 exposed pups preserves lung structure and function through enhanced pro-angiogenic signaling.