Kinetic vasculogenic analyses of endothelial colony forming cells exposed to intrauterine diabetes

Abstract

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, including a tissue cytometry approach to quantify the frequency and localization of dividing ECFCs within cell networks. Additionally, FIJI TrackMate was used to quantify ECFC displacement and speed at the single cell level during network formation. These novel approaches were then applied to determine how intrauterine exposure to maternal type 2 diabetes mellitus (T2DM) impairs fetal ECFC vasculogenesis, and whether increased Transgelin 1 (TAGLN) expression in ECFCs from pregnancies complicated by gestational diabetes (GDM) was sufficient to impair vasculogenesis. Fetal ECFCs exposed to maternal T2DM formed fewer initial network structures, which were not stable over time. Correlation analyses identified that ECFC samples with greater division in branches formed fewer closed network structures and that reductions in ECFC movement decreased structural connectivity. To identify specific cellular mechanisms and signaling pathways altered in ECFCs following intrauterine GDM exposure, these new techniques were also applied in TAGLN expression studies. Similarly, ECFCs from GDM pregnancies and ECFCs overexpressing TAGLN exhibited impaired vasculogenesis and decreased migration. Both ECFCs from GDM pregnancies as well as ECFCs over expressing TAGLN exhibited increased phosphorylation of myosin light chain. Reduction of myosin light chain phosphorylation via Rho kinase inhibition increased ECFC migration; therefore, increased TAGLN was sufficient to impair ECFC vasculogenic function. Overall, identification of these novel phenotypes provides evidence for the molecular mechanisms contributing to aberrant ECFC vasculogenesis. Determining how intrauterine exposure to maternal T2DM and GDM alters fetal ECFC function will enable greater understanding of the chronic vascular pathologies observed in children from pregnancies complicated by diabetes mellitus.