Transgelin induces dysfunction of fetal endothelial colony-forming cells from gestational diabetic pregnancies

Fetal exposure to gestational diabetes mellitus (GDM) predisposes children to future health complications including hypertension and cardiovascular disease. A key mechanism by which these complications occur is through the functional impairment of vascular progenitor cells, including endothelial colony-forming cells (ECFCs). Previously, we showed that fetal ECFCs exposed to GDM have decreased vasculogenic potential and altered gene expression. In this study, we evaluate whether transgelin (TAGLN), which is increased in GDM-exposed ECFCs, contributes to vasculogenic dysfunction. TAGLN is an actin-binding protein involved in the regulation of cytoskeletal rearrangement. We hypothesized that increased TAGLN expression in GDM-exposed fetal ECFCs decreases network formation by impairing cytoskeletal rearrangement resulting in reduced cell migration. To determine if TAGLN is required and/or sufficient to impair ECFC network formation, TAGLN was reduced and overexpressed in ECFCs from GDM and uncomplicated pregnancies, respectively. Decreasing TAGLN expression in GDM-exposed ECFCs improved network formation and stability as well as increased migration. In contrast, overexpressing TAGLN in ECFCs from uncomplicated pregnancies decreased network formation, network stability, migration, and alignment to laminar flow. Overall, these data suggest that increased TAGLN likely contributes to the vasculogenic dysfunction observed in GDM-exposed ECFCs, as it impairs ECFC migration, cell alignment, and network formation. Identifying the molecular mechanisms underlying fetal ECFC dysfunction following GDM exposure is key to ascertain mechanistically the basis for cardiovascular disease predisposition later in life.

Mesenchyme Homeobox 2 Enhances Migration of Endothelial Colony Forming Cells Exposed to Intrauterine Diabetes Mellitus

Diabetes mellitus (DM) during pregnancy has long-lasting implications for the fetus, including cardiovascular morbidity. Previously, we showed that endothelial colony forming cells (ECFCs) from DM human pregnancies have decreased vasculogenic potential. Here, we evaluate whether the molecular mechanism responsible for this phenotype involves the transcription factor, Mesenchyme Homeobox 2 (MEOX2). In human umbilical vein endothelial cells, MEOX2 upregulates cyclin-dependent kinase inhibitor expression, resulting in increased senescence and decreased proliferation. We hypothesized that dysregulated MEOX2 expression in neonatal ECFCs from DM pregnancies decreases network formation through increased senescence and altered cell cycle progression. Our studies show that nuclear MEOX2 is increased in ECFCs from DM pregnancies. To determine if MEOX2 is sufficient and/or required to induce impaired network formation, MEOX2 was overexpressed and depleted in ECFCs from control and DM pregnancies, respectively. Surprisingly, MEOX2 overexpression in control ECFCs resulted in increased network formation, altered cell cycle progression, and increased senescence. In contrast, MEOX2 knockdown in ECFCs from DM pregnancies led to decreased network formation, while cell cycle progression and senescence were unaffected. Importantly, migration studies demonstrated that MEOX2 overexpression increased migration, while MEOX2 knockdown decreased migration. Taken together, these data suggest that altered migration may be mediating the impaired vasculogenesis of ECFCs from DM pregnancies. While initially believed to be maladaptive, these data suggest that MEOX2 may serve a protective role, enabling increased vessel formation despite exposure to a DM intrauterine environment. J. Cell. Physiol. 232: 1885-1892, 2017. © 2016 Wiley Periodicals, Inc.

Kinetic analyses of vasculogenesis inform mechanistic studies

Vasculogenesis is a complex process by which endothelial stem and progenitor cells undergo de novo vessel formation. Quantitative assessment of vasculogenesis is a central readout of endothelial progenitor cell functionality. However, current assays lack kinetic measurements. To address this issue, new approaches were developed to quantitatively assess in vitro endothelial colony-forming cell (ECFC) network formation in real time. Eight parameters of network structure were quantified using novel Kinetic Analysis of Vasculogenesis (KAV) software. KAV assessment of structure complexity identified two phases of network formation. This observation guided the development of additional vasculogenic readouts. A tissue cytometry approach was established to quantify the frequency and localization of dividing ECFCs. Additionally, Fiji TrackMate was used to quantify ECFC displacement and speed at the single-cell level during network formation. These novel approaches were then implemented to identify how intrauterine exposure to maternal diabetes mellitus (DM) impairs fetal ECFC vasculogenesis. Fetal ECFCs exposed to maternal DM form fewer initial network structures, which are not stable over time. Correlation analyses demonstrated that ECFC samples with greater division in branches form fewer closed network structures. Additionally, reductions in average ECFC movement over time decrease structural connectivity. Identification of these novel phenotypes utilizing the newly established methodologies provides evidence for the cellular mechanisms contributing to aberrant ECFC vasculogenesis.

Epigenetic Regulation of Placenta-Specific 8 Contributes to Altered Function of Endothelial Colony-Forming Cells Exposed to Intrauterine Gestational Diabetes Mellitus

Intrauterine exposure to gestational diabetes mellitus (GDM) is linked to development of hypertension, obesity, and type 2 diabetes in children. Our previous studies determined that endothelial colony-forming cells (ECFCs) from neonates exposed to GDM exhibit impaired function. The current goals were to identify aberrantly expressed genes that contribute to impaired function of GDM-exposed ECFCs and to evaluate for evidence of altered epigenetic regulation of gene expression. Genome-wide mRNA expression analysis was conducted on ECFCs from control and GDM pregnancies. Candidate genes were validated by quantitative RT-PCR and Western blotting. Bisulfite sequencing evaluated DNA methylation of placenta-specific 8 (PLAC8). Proliferation and senescence assays of ECFCs transfected with siRNA to knockdown PLAC8 were performed to determine functional impact. Thirty-eight genes were differentially expressed between control and GDM-exposed ECFCs. PLAC8 was highly expressed in GDM-exposed ECFCs, and PLAC8 expression correlated with maternal hyperglycemia. Methylation status of 17 CpG sites in PLAC8 negatively correlated with mRNA expression. Knockdown of PLAC8 in GDM-exposed ECFCs improved proliferation and senescence defects. This study provides strong evidence in neonatal endothelial progenitor cells that GDM exposure in utero leads to altered gene expression and DNA methylation, suggesting the possibility of altered epigenetic regulation.