The authors sought to identify novel biomarkers for early detection of neural tube defects (NTDs) in human fetuses.
Amniotic fluid and serum were drawn from women in the second trimester of pregnancy. The study group included 2 women pregnant with normal fetuses and 4 with fetuses displaying myelomeningocele (n = 1), anencephaly (n = 1), holoprosencephaly (n = 1), or encephalocele (n = 1). Amniotic fluid stem cells (AFSCs) were isolated and cultured. The cells were immunostained for the stem cell markers Oct4, CD133, and Sox2; the epigenetic biomarkers H3K4me2, H3K4me3, H3K27me2, H3K27me3, H3K9Ac, and H3K18Ac; and the histone modifiers KDM6B (a histone H3K27 demethylase) and Gcn5 (a histone acetyltransferase). The levels of 2 markers for neural tube development, bone morphogenetic protein–4 (BMP4) and sonic hedgehog (Shh), were measured in amniotic fluid and serum using an enzyme-linked immunosorbent assay.
The AFSCs from the woman pregnant with a fetus affected by myelomeningocele had higher levels of H3K4me2, H3K4me3, H3K27me2, and H3K27me3 and lower levels of KDM6B than the AFSCs from the women with healthy fetuses. The levels of H3K9ac, H3K18ac, and Gcn5 were also decreased in the woman with the fetus exhibiting myelomeningocele. In AFSCs from the woman carrying an anencephalic fetus, levels of H3K27me3, along with those of H3K9Ac, H3K18ac, and Gcn5, were increased, while that of KDM6B was decreased. Compared with the normal controls, the levels of BMP4 in amniotic fluid and serum from the woman with a fetus with myelomeningocele were increased, whereas levels of Shh were increased in the woman pregnant with a fetus displaying anencephaly.
The levels of epigenetic marks, such as H3K4me, H3K27me3, H3K9Ac, and H3K18A, in cultured AFSCs in combination with levels of key developmental proteins, such as BMP4 and Shh, are potential biomarkers for early detection and identification of NTDs in amniotic fluid and maternal serum.