Direct toxicity of insulin on the human placenta and protection by metformin.

Abstract

OBJECTIVE\nTo study the effects of insulin and metformin on primary trophoblasts from early pregnancies.\n\n\nDESIGN\nExperimental in\xa0vitro study.\n\n\nSETTING\nAcademic research institute.\n\n\nPATIENT(S)\nTrophoblasts from healthy patients undergoing first trimester elective termination of pregnancy and primary lung fibroblasts (IMR-90).\n\n\nINTERVENTION(S)\nCulture and treatment with insulin and metformin of primary trophoblasts and primary lung fibroblasts (IMR-90).\n\n\nMAIN OUTCOME MEASURE(S)\nDNA damage measured by expression of γ-H2AX with immunofluorescence and Western blot. Apoptosis measured by expression of cleaved caspase-3 by Western blot. Cell survival measured by cell proliferation assay.\n\n\nRESULT(S)\nCulture of purified primary trophoblast cells in the presence of insulin at levels as low as 1\xa0nM resulted in a 386% increase in the number of cell with elevated γ-H2AX expression, a 66% reduction in cell survival and a marked increase of cleaved caspase-3 expression. Pretreatment of trophoblasts with therapeutic doses of metformin prevented the detrimental effects of insulin. Treatment with insulin and/or metformin had no effects on primary fibroblasts.\n\n\nCONCLUSION(S)\nElevated insulin levels are directly toxic to first trimester trophoblasts and result in increased DNA damage, apoptosis, and decreased cell survival. These effects are prevented by metformin. Trophoblast cells from early pregnancy are uniquely vulnerable to elevated levels of insulin. These findings, if confirmed in\xa0vivo, suggest that there may be a role for insulin resistance screening before attempting pregnancy and for focusing on prevention of hyperinsulinemia during early pregnancy.