BS48 Transient exposure to the diabetic milieu in gestational diabetes imposes a persistent phenotypic switch in human umbilical artery smooth muscle cells

Introduction Gestation diabetes (GDM) is the transient development of diabetes during pregnancy, which resolves after delivery. It affects 1 in 20 UK pregnancies and predisposes both mother and child to early development of metabolic syndrome, type 2 diabetes (T2DM) and cardiovascular disease. Smooth muscle cells (SMC) are the principal cell type in the vascular wall and previous studies have shown that T2DM-SMC exhibit sustained phenotypic changes in morphology, proliferation, and become senescent with a persistently activated DNA damage response. However, it is unknown how long these patients had T2DM, and thus how long an exposure to the diabetic milieu is needed to induce persistent SMC dysfunction. The present study is the first to characterise primary SMC phenotype from the umbilical artery of mothers with and without GDM, to examine whether phenotypic change can be induced in less than 9 months of diabetes. Methods Human umbilical artery SMC were isolated from GDM and non-diabetic (ND) donors via explant. SMC identify was validated using immunocytochemistry, and morphological characteristics were analysed using light microscopy and ImageJ. Senescence was measured by beta-galactosidase staining, gene expression of senescence-associated cytokines by qPCR, and proliferation by cell counting. Results The identity of explanted SMC was confirmed by co-staining for alpha smooth muscle actin and smooth muscle myosin heavy chain. GDM-SMC had a greater diversity in size and were on average 39.9% larger than ND-SMC, though they retained their spindle morphology. GDM-SMC had significantly higher senescence scores (69% increase) and incidence of multinucleation (43%), with reduced expression of LMNB1 and increased expression of interleukins -8 (453% increase) and -17A (1533% increase). Proliferative capacity was unchanged. Conclusion GDM-SMC present evidence of persistent DNA damage after transient (maximum 9 months) exposure to the diabetic milieu, which is similar to the characteristics seen in T2DM-SMC. However, changes in morphology and proliferation were less pronounced in GDM-SMC. This study has therefore revealed that transient exposure to diabetes in vivo is enough to impart persistent phenotypic change in vitro, highlighting a potential mechanism by which GDM mothers and children are predisposed to vascular disease. Furthermore, given that morphological and proliferative changes in GDM are less pronounced than T2DM, this suggests that enhanced DNA damage and senescence is the triggering factor for SMC dysfunction in diabetes which is worthy of further study. Conflict of Interest None