Edelfosine induces cell cycle arrest and apoptosis in vascular smooth muscle cells to suppress neointimal hyperplasia

Neointimal hyperplasia, driven by abnormal proliferation and survival of vascular smooth muscle cells (VSMCs), underlies atherosclerotic stenosis and restenosis after angioplasty or stenting. Edelfosine (ET-18-OCH₃) is an alkylphospholipid with pro-apoptotic activity. We tested whether edelfosine limits pathological VSMC growth and neointimal lesion formation by enforcing cell-cycle arrest and Apoptosis. Primary VSMCs from mouse and rat aortas were exposed to edelfosine (0–15 µM). Viability (MTT) and DNA synthesis (BrdU) were quantified. DNA content and binucleation were assessed by laser scanning cytometry and immunofluorescence. Apoptosis was measured by TUNEL and by cleavage of caspase-9, -7, and -3, with the pan-caspase inhibitor Z-VAD-FMK to test Caspase dependence. Apoptosis in live cells was also analyzed using Annexin V and propidium iodide staining. Intracellular Ca²⁺ was imaged and measured in fluorescent Ca²⁺ indicator-loaded cells. In vivo, carotid artery ligation in mice induced neointimal hyperplasia; edelfosine or vehicle was delivered locally, and lesion size was measured morphometrically. Vascular Apoptosis was further evaluated by TUNEL. Edelfosine reduced VSMC viability and proliferation in a dose- and time-dependent manner; at 5–10 µM it suppressed BrdU incorporation by > 90% and triggered extensive cell death. Cells accumulated with 4 N DNA content and showed increased binucleation, consistent with G₂/M arrest and failed cytokinesis. Approximately 40% of edelfosine-treated VSMCs were TUNEL-positive versus ~ 5% with vehicle (p < 0.001), coincident with activation of caspase-9, -7, and -3; Z-VAD-FMK prevented Caspase-3 cleavage and reduced TUNEL positivity. Mechanistically, edelfosine induced endoplasmic reticulum (ER) stress (increased phospho-eIF2α), upregulated Bax, and evoked a rapid rise in intracellular Ca²⁺ in the presence of extracellular Ca²⁺. Edelfosine-induced Ca²⁺ elevation was reduced by extracellular Ca²⁺ chelation with EGTA, blockade of VGCCs with nifedipine, and perturbation of IP₃ receptor-linked Ca²⁺ pathways with 2-APB. In vivo, edelfosine significantly reduced neointimal lesion size after carotid ligation, lowering the intima-to-lumen ratio (p < 0.05) and increasing TUNEL positivity within the vessel wall. Edelfosine enforces G₂/M cell-cycle arrest and caspase-dependent Apoptosis in VSMCs, linked to ER stress and Ca²⁺ influx, thereby limiting neointimal hyperplasia after blood flow cessation. Local edelfosine delivery may offer a dual anti-proliferative and pro-apoptotic strategy to prevent restenosis.

Apoptosis; Carotid artery ligation; Cell-cycle arrest; Edelfosine; Endoplasmic reticulum stress; Neointimal hyperplasia; Restenosis; Vascular smooth muscle cell.