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Prenatal Ad.VEGF Gene Therapy Increases Fetal Growth Velocity and Expression of VEGF Receptors in an Ovine Parad PowerPoint Presentation
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Prenatal Ad.VEGF Gene Therapy Increases Fetal Growth Velocity and Expression of VEGF Receptors in an Ovine Parad

Prenatal Ad.VEGF Gene Therapy Increases Fetal Growth Velocity and Expression of VEGF Receptors in an Ovine Parad

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Prenatal Ad.VEGF Gene Therapy Increases Fetal Growth Velocity and Expression of VEGF Receptors in an Ovine Parad

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  1. Prenatal Ad.VEGF Gene Therapy Increases Fetal Growth Velocity and Expression of VEGF Receptors in an Ovine Paradigm of Fetal Growth Restriction DJ Carr, RP Aitken, JS Milne, DM Peebles, J Martin, I Zachary, JM Wallace, AL David Prenatal Cell and Gene Therapy Group, UCL Institute for Women’s Health Rowett Institute of Nutrition and Health, University of Aberdeen Centre for Cardiovascular Medicine and Biology, UCL

  2. Complicates 8% of pregnancies (severe in 1:500) • Major cause of perinatal mortality and morbidity • No effective treatment • Outcome dependent on gestational age • Reduced uterine blood flow (in early onset FGR) Fetal Growth Restriction – FGR

  3. Prenatal Ad.VEGF Gene Therapy • Uterine artery injection of Ad.VEGF (adenoviral constructs encoding • vascular endothelial growth factor gene) in normal sheep pregnancy • increases uterine blood flow for at least 4 weeks (Mehta et al. 2011) Ad.VEGF 40 % increase Ad.LacZ 16 % increase

  4. 58th Annual SGI Meeting, March 2011 • Ad.VEGF treatment of growth-restricted sheep fetuses: • Significant increase in fetal growth velocity • (maximum effect observed 3 to 4 weeks post-treatment) • Tendency towards increased lamb birth weight near to term p=0.081 * * * p=<0.05

  5. ↓ Fetal weight (30-40%) ↓ Placental size ↓ Gestation length ↑ Perinatal mortality ↓ Placental vascularity ↓ Placental angiogenic factors ↓ Placental hormone production ↓ Uterine blood flow (42%) (Wallace 1996–2011) Overnourished Adolescent Paradigm of FGR

  6. Aims • To determine the effects of Ad.VEGF therapy in FGR on: • Serial measurements of uterine blood flow • Fetal growth (relative to normally growing controls) • Fetal weight and fetal body composition in late gestation • Placental expression of selected angiogenic factors/receptors

  7. 1. Superovulation + laparoscopic intrauterine insemination (single sire) Materials and Methods 2. Embryo Recovery • Singletons • Known gestational age • Maximised genetic homogeneity Embryo Recovery 3. Embryo Transfer

  8. Experimental Design n = 57 Viable pregnancies n = 45 High intake n = 12 Control intake

  9. Uterine artery injection (mid-gestation) Overnourished ewes randomised to Ad.VEGF, Ad.LacZ or Saline

  10. Experimental Design n = 57 Viable pregnancies n = 45 High intake n = 12 Control intake +Saline +LacZ +Saline +Ad.VEGF n = 12 Control n = 18 VEGF n = 13 Saline n = 14 LacZ

  11. Placement of uterine artery flow probes

  12. Telemetric monitoring of uterine blood flow

  13. Abdominal circumference Biparietal diameter Umbilical artery Dopplersl Renal length Renal transverse / AP diameters Deepest vertical pool of liquor

  14. Fetal Cotyledon Necropsy (D131) and Placental Analyses Uterine Wall Maternal Caruncle • Placentome separated into maternal (caruncular) • and fetal (cotyledonary) portions and snap frozen • RNA extracted and reversed transcribed to cDNA • Quantitative RT-PCR for eNOS, VEGF, Flt1 and KDR

  15. Uterine Blood Flow

  16. Fetal Growth Velocity A p = 0.031 / p = 0.047 B p = 0.032 / p = 0.016

  17. Fetal Weight in Late Gestation

  18. Proportions of Fetuses >2SD Below Control Mean (Control mean = 5084g , SD = 431g, >2SD cut-off = 4222g) FGR >2SD FGR <2SD p = 0.033 (Fisher’s exact test) Saline+LacZ VEGF

  19. Serial Ultrasound BPD to AC Ratios A p = 0.007 / p = 0.016 B p = 0.016 / p = <0.001 C p = <0.001 / p = <0.001

  20. Indices of Fetal Brain Sparing at Necropsy: Relative Brain Weight (g/kg)Brain:Liver Weight Ratio p=0.046 p=0.009 p=0.001 p=<0.001

  21. Placental mRNA Expression: VEGF & eNOS VEGF / 18s eNOS / 18s

  22. Placental mRNA Expression: Flt1 & KDR Flt1 / 18s KDR / 18s

  23. Ad.VEGF treatment in the overnourished adolescent sheep paradigm of FGR resulted in: • Increased fetal growth velocity relative to untreated FGR groups (maximum effect 3 to 4 weeks post- administration) • Fewer fetuses >2SD below control mean in late gestation • Evidence of an attenuated brain sparing effect: • ↓ BPD:AC ratios on serial ultrasound examination • ↓ relative brain weight / brain to liver weight ratio • No measurable effect on uterine blood flow • Increased caruncular mRNA expression of Flt1 and KDR Summary

  24. Acknowledgements Funded by the Wellcome Trust, Wellbeing of Women and Ark Therapeutics plc