(679) Impact of amnioinfusions on the ultrastructure of the amnion in a rodent model

Amnioinfusions are an important part of many fetal therapy procedures. Prior research has shown that in vitro, amnioinfusions with normal saline (NS) and lactated ringer’s (LR) leads to apoptosis of human amniotic membranes when compared with a novel synthetic amniotic fluid. We sought to evaluate the effect of amnioinfusions with commercially available fluids compared to a novel synthetic amniotic fluid in vivo in a rodent model.

Study Design:

This study was IACUC approved through Cincinnati Children’s Hospital Medical Center. At day E17.5, pregnant rats underwent midline laparotomy to amnio exchange with removal of amniotic fluid around the rat fetus and 1 to 1 replacement of fluid with NS, LR, or a synthetic amniotic fluid, termed “amnio-well” (AW). As a control, some fetuses in each pregnant rat did not undergo amnio-exchange. Rats were harvested at day E20.5 and uterus and amnion specimens were evaluated via electron microscopy for ultrastructure changes as well as the rat amnions evaluating for matrix metalloproteinase 9 (MMP9) expression (a known executor of collagenase and amnion degradation in rodents) via Western Blot. Vinculin was used as a loading control. Western Blot images were analyzed via ImageJ® Software.

Results: Under scanning electron microscopy, there was an increase in amniotic microfractures, as well as amniotic epithelial cellular shrinkage, signs indicative of impending rupture of membranes. These changes were not seen with amnio well nor control (Figure). The MMP9/Vinculin expression was noted to be 1.53 (IQR  1.09, 2.27) in control, compared with , with 2.82 (IQR 2.01, 3.09, p = 0.072) in NS, 5.86 (IQR 1.06, 6.72, p = 0.038) in LR and 1.58 (IQR 1.41, 1.74, p = 0.395) in AW.

Conclusion: The ultrastructure of the amnion, after amnio exchange with normal saline and lactated ringers, was notable for increased microfractures and cellular shrinkage, compared to use of a synthetic amniotic fluid. Increased MMP9 production was noted in LR when compared with control. Further study into the impact of amnioinfusions on the amniotic membrane is warranted.