Effects Of Low Intensity Laser Irradiation On Coronary Restenosis: A Vitro Study

Coronary heart disease (CHD) is a kind of serious cardiovascular disease. Percutaneous Transluininal Coronary Angioplasty (PTCA) and other Percutaneous Coronary Interventions (PCI) are major ways to treat the CHD. Restenosis (RS) is the Achilles heel of PTCA and PCI. Many researches have proved that the excessive proliferation of the vascular smooth muscle cells (VSMCs) is the main reason of RS. And the unbalance of the VSMCs proliferation and the apoptosis increases the neointima's thickness.This study focuses on the effects of low intensity laser (LIL) irradiation on VSMCs to prevent coronary restenosis. A 532nm laser irradiation system and a 632.8nm laser irradiation system were established. Then VSMCs were cultured in vitro and the cultured cells were identified as VSMCs by such methods as microscope, electron microscope and histochemistry.The cultured VSMCs were irradiated in vitro by the laser systems and the effects were detected by MTT. The results showed that both 532nm laser and 632.8nm laser inhibited the proliferation of the VSMCs. The difference of wavelength is not significant to the effects. The further study detected if laser power and/or exposure duration affects the proliferation of the VSMCs at different time point after 532nm laser exposure. The results showed that not only the power but also the duration influenced the proliferation of the VSMCs. The proliferation was significantly inhibited with the exposure of the 40mW 532nm laser, and 5 minutes' exposure by the end of the observation (the 8' day).The above study showed that the irradiation of LIL inhibits the proliferation of the VSMCs. But whether they were inhibited through apoptosis still left a question. Then the apoptosis of the VSMCs were observed after the irradiation of 532nm LIL. The apoptosis bodies were observed through theelectron microscope. TUNEL test also showed positive signal. All of these confirmed the occurrence of the apoptosis after the irradiation. But the Giemsa staining and FCM showed the negative results. The possible causes might be the methods themselves. The relationship between the dosage and the apoptosis was also detected by TUNEL. The correlation of them was significant. The higher of the dosage, the more propotion of apoptosis of the VSMCs was.In conclusion, our study showed that LIL inhibits the proliferation of the VSMCs and promotes their apoptosis in vitro. LIL irradiation is a kind of promising procedure to prevent RS. This study established a foundation for the corresponding studies in vivo and in the clinic.