New insight into mitochondrial changes in vascular endothelial cells irradiated by gamma ray

Abstract

Purpose: To investigate alterations of mitochondria in irradiated endothelial cells to further elucidate the mechanism underlying radiation-induced heart disease.

Materials and methods: Experiments were performed using human umbilical vein endothelial cells (HUVECs). HUVECs were irradiated with single gamma ray dose of 0, 5, 10 and 20 Gy, respectively. Apoptosis was assessed by flow cytometry at 24, 48 and 72 h post-irradiation, respectively. The intracellular reactive oxygen species (ROS) was measured with 2′,7′-dichlorofluorescein-diacetate (DCFH-DA) at 24 h post-irradiation. Mitochondrial membrane potential (ΔΨm) by JC-1 and the opening of mitochondrial permeability transition pore (mPTP) by a calcein-cobalt quenching method were detected at 24 h post-irradiation in order to measure changes of mitochondria induced by gamma ray irradiation.

Results: Gamma ray irradiation increased HUVECs apoptosis in a dose-dependent and time-dependent manner. Irradiation also promoted ROS production in HUVECs in a dose-dependent manner. At 24 h post-irradiation, the results showed that irradiation decreases ΔΨm, however, paradoxically, flow cytometry showed green fluorescence instensity higher in irradiated HUVECs than in control HUVECs in an irradiation dose-dependent manner which indicated gamma ray irradiation inhibited mPTP opening in HUVECs.

Conclusions: Gamma ray irradiation induces apoptosis and ROS production of endothelial cells, and decreases ΔΨm meanwhile contradictorily inhibiting the opening of mPTP.

Keywords:

• Mitochondrial membrane potential
• mitochondrial permeability transition pore
• reactive oxygen species
• apoptosis
• human umbilical vein endothelial cells
• gamma ray irradiation

Disclosure statement

The authors report no conflict of interest. The authors are responsible for the content and writing of the paper.

Additional information

Funding

This work is supported by grants from National Natural Science Foundation of China (no. 81102079) and China Postdoctoral Science Foundation (no. 201003776). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.