(91) Impact of a synthetic amniotic fluid upon fetal lung development

Serial amnioinfusions in the setting of anyhydramnios seek to promote fetal lung development, however these procedures can be fraught with complications, and the fluid infused (Normal Saline-NS or Lactated Ringer’s-LR) is not designed for the in-utero environment. We previously designed a synthetic amniotic fluid (Amnio-well - AW), which minimizes reactive oxygen species damage to the amniotic membrane. Given the interplay between the amniotic fluid and fetal lungs, we sought to evaluate the impact of AW on fetal lung development.

Study Design: At E17.5, pregnant rats underwent laparotomy to amniotic fluid replacement with either NS, LR, AW, or AW plus epidermal and fibroblast growth factor (AW++), with sham surgery as a control. Fetal lungs were harvested at E20.5. Histology was evaluated by H&E staining, using morphometric measurement of fractional airspace to estimate growth. Gene expression for surfactant A, B, and C (SP-A, SP-B, SP-C) was compared between groups via reverse transcriptase PCR and immunofluorescence. Inflammatory gene panels were run to identify patterns in abnormal inflammation in the various treatment groups.

Results: Fetal lungs from NS and LR were noted to have increased edema, macrophage infiltration, and decreased airspace (p< 0.001) (Figure 1).  When evaluating surfactant expression, there was increased SP-B, SP-C expression with AW relative to control, significantly decreased SP-A, SP-B, SP-C expression with both NS and LR, and mildly decreased SP-A, SP-B, SP-C with AW++ (Figure 2). Inflammatory gene profiling revealed marked alterations in histamines, annexins, phospholipase, and immune cell recruitment in NS and LR, indicating abnormal cell membrane integrity (Figure 2). The closest profile to control was AW, with altered gene expression in 10/94 genes (9 upregulated, 1 downregulated), vs 41 genes with NS (22 up, 19 down), 33 with LR (14 up, 19 down), and 12 with AW++ (10 up, 2 down).

Conclusion: A synthetic amniotic fluid leads to decreased lung inflammatory profiles and improved surfactant expression compared to commercially available fluids when used for amnioinfusion.