2016•Arteriosclerosis Thrombosis and Vascular BiologyRequires access
Abstract 626: Oxidized Low-density Lipoprotein-induced Cell Membrane Damage in Bone Marrow Stem Cells is Independent of ROS Formation
Xin Li, Yuqi Cui, Tao Tan, Chandrakala Aluganti Narasimhulu, Yuan Xiao, Jia Zhang, Hong Hao, Lingjuan Liu, Jianjie Ma, Catherine M. Verfaillie, Sampath Parthasarathy, Hua Zhu, Zhenguo Liu
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Abstract
Objectives: Membrane repair mechanism is important to the cell survival and function. MG53, also known as TRIM72, is a critical component in the membrane repair process. We have demonstrated that cell membrane damage was involved in the impaired survival of bone marrow stem cells (BMSCs) by oxidized low-density lipoprotein (ox-LDL) in vitro, and recombinant human MG53 protein (rhMG53) significantly protected the cell membrane of BMSCs and enhanced their survival. However, the mechanism(s) for ox-LDL-induced membrane damage in BMSCs is unclear. It is well known that ox-LDL is a potent oxidative agent with formation of abundant reactive oxygen species ( ROS ). The present study was designed to determine the role of ROS in ox-LDL-induced membrane damage in BMSCs. Methods: Rat bone marrow multipotent adult progenitor cells ( MAPCs ) were cultured with and without ox-LDL (0-20 ug/ml) for up to 48 hrs. Exposure of MAPCs to ox-LDL led to increased LDH release to the media and entry of fluorescent dye FM1-43 measured under confocal microscope, suggesting damage to the plasma membrane. Ox-LDL also generated excessive ROS as measured with electron paramagnetic resonance spectroscopy. While antioxidant N-acetylcysteine (NAC) completely blocked ROS production from ox-LDL, it failed to prevent ox-LDL-induced cell death or membrane damage. When MAPCs were treated with rhMG53, ox-LDL induced LDH release and FM1-43 dye entry were significantly reduced. Interestingly, NAC treatment significantly potentiated the protective effect of rhMG53 on ox-LDL-induced membrane damage with enhanced cell survival. Western blot analysis showed that ox-LDL significantly reduced the level of rhMG53 both in vitro and in vivo that was substantially prevented with NAC treatment. Conclusion: Our data suggest that membrane damage induced by ox-LDL contributed to the impaired survival of MAPCs independent of ROS production. NAC potentiated the protective effect of rhMG53 on ox-LDL-induced membrane damage of BMSCs via preventing ox-LDL-induced reduction of rhMG53 level.