Alterations in maternal-fetal cellular trafficking after fetal surgery

Abstract

Background/purpose: Bidirectional trafficking of cells between the mother and the fetus is routine in pregnancy and a component of maternal-fetal tolerance. Changes in fetal-to-maternal cellular trafficking have been reported in prenatal complications, but maternal-to-fetal trafficking has never been studied in the context of fetal intervention. We hypothesized that patients undergoing open fetal surgery would have altered maternal-fetal cellular trafficking.

Methods: Cellular trafficking was analyzed in patients with myelomeningocele (MMC) who underwent open fetal surgical repair (n = 5), patients with MMC who had routine postnatal repair (n = 6), and healthy control healthy patients (n = 9). As an additional control for the fetal operation, trafficking was also analyzed in patients who were delivered by an ex utero intrapartum treatment procedure (n = 6). Microchimerism in maternal and cord blood was determined using quantitative real-time polymerase chain reaction for nonshared alleles.

Results: Maternal-to-fetal trafficking was significantly increased in patients who underwent open fetal surgery for MMC compared with healthy controls, patients who underwent postnatal MMC repair, and patients who underwent ex utero intrapartum treatment. There were no differences in fetal-to-maternal cell trafficking among groups.

Conclusion: Patients undergoing open fetal surgery for MMC have elevated levels of maternal microchimerism. These results suggest altered trafficking and/or increased proliferation of maternal cells in fetal blood and may have important implications for preterm labor.

Figure 1

Maternal microchimerism. The percentage of maternal cells in cord blood was significantly different among groups (Kruskal Wallis for all groups, p=0.01. *= p<0.05 by pairwise comparison using Mann-Whitney; **= p<0.05 by Kruskal-Wallis with Dunn's post-hoc comparison.) MMC = myelomeningocele, EXIT = ex utero intrapartum treatment. Maternal to fetal cellular trafficking could not be analyzed in one normal patient due to an absence of non-shared alleles on PCR.

Figure 2

Fetal microchimerism. The percentage of fetal cells in maternal blood was not significantly different among groups. MMC = myelomeningocele, EXIT = ex utero intrapartum treatment. Fetal to maternal cellular trafficking could not be analyzed in two postnatal MMC patients due to an absence of non-shared alleles on PCR.