Transient receptor potential channel M2 contributes to neointimal hyperplasia in vascular walls

Background: A hallmark of atherosclerosis is progressive intimal thickening (namely neointimal hyperplasia), which leads to occlusive vascular diseases. Over-production of reactive oxygen species (ROS) and alteration of Ca²⁺ signaling are among the key factors contributing to neointimal growth. In the present study, we investigated the role of TRPM2, a ROS-sensitive Ca²⁺ entry channel, in neointimal hyperplasia. Methods and results: Perivascular cuffs were used to induce neointimal hyperplasia in rat/mouse arteries. Immunostaining showed numerous TRPM2-positive smooth muscle cells in neointimal regions. ROS were over-produced and PCNA-positive proliferating cells were numerous in the neointimal regions. The neointimal hyperplasia was substantially reduced in Trpm2 knockout mice compared with wild-type mice. In the cultured rat/mouse aortic smooth muscle cells, H₂O₂ treatment was found to stimulate cell proliferation and migration. The effect of H₂O₂ was reduced by a TRPM2-specific blocking antibody TM2E3 or Trpm2 knockout. The signaling molecules downstream of TRPM2 were found to be Axl and Akt. Conclusions: These data suggest a critical functional role of TRPM2 in the progression of neointimal hyperplasia. The study also highlights the possibility of targeting TRPM2 as a potential therapeutic option for the treatment of occlusive vascular diseases.