Amniotic Fluid Mesenchymal Stromal Cells Derived from Fetuses with Isolated Cardiac Defects Exhibit Decreased Proliferation and Cardiomyogenic Potential

SIMPLE SUMMARY: Congenital heart defect (CHD) is the most common birth defect that affects the structure of the heart from birth. A possible reason for this occurrence could be alterations in the properties of the stem cells associated with fetal heart development. In this study, we compared the growth and cardiomyogenic potential of fetal-derived amniotic fluid mesenchymal stem cells (AF-MSCs) from isolated congenital heart defective fetuses (ICHD) with AF-MSCs of normal fetuses. The ICHD AF-MSCs showed a defect in the ability to grow efficiently and displayed increased senescence and DNA damage processes compared to normal AF-MSCs. Furthermore, the ICHD AF-MSCs showed cardiomyogenic differentiation defects that were accompanied by decreased expression of various proteins, including cardiac progenitor markers, transcription factors, and structural proteins, which are necessary for proper heart development. Overall, our study highlights that these defects in AF-MSCs of ICHD fetuses possibly contribute to CHDs and may lead to improper heart development. ABSTRACT: Amniotic fluid mesenchymal stromal cells (AF-MSCs) represent an autologous cell source to ameliorate congenital heart defects (CHDs) in children. The AF-MSCs, having cardiomyogenic potential and being of fetal origin, may reflect the physiological and pathological changes in the fetal heart during embryogenesis. Hence, the study of defects in the functional properties of these stem cells during fetal heart development will help obtain a better understanding of the cause of neonatal CHDs. Therefore, in the present study, we compared the proliferative and cardiomyogenic potential of AF-MSCs derived from ICHD fetuses (ICHD AF-MSCs) with AF-MSCs from structurally normal fetuses (normal AF-MSCs). Compared to normal AF-MSCs, the ICHD AF-MSCs showed comparable immunophenotypic MSC marker expression and adipogenic and chondrogenic differentiation potential, with decreased proliferation, higher senescence, increased expression of DNA-damaged genes, and osteogenic differentiation potential. Furthermore, the expression of cardiac progenitor markers (PDGFR-α, VEGFR-2, and SSEA-1), cardiac transcription factors (GATA-4, NKx 2-5, ISL-1, TBX-5, TBX-18, and MeF-2C), and cardiovascular markers (cTNT, CD31, and α-SMA) were significantly reduced in ICHD AF-MSCs. Overall, these results suggest that the AF-MSCs of ICHD fetuses have proliferation defects with significantly decreased cardiomyogenic differentiation potential. Thus, these defects in ICHD AF-MSCs highlight that the impaired heart development in ICHD fetuses may be due to defects in the stem cells associated with heart development during embryogenesis.