Preventive Effects Of Low Intensity Microwave On Damages Of Cells In Hematopoietic System Induced By γ-rays And Doxorubicin Hydrochloride

Objective:To explore the protective effects of low intensity microwave onγ-rays and doxorubicin hydrochloride (DOX)-induced damages in primarily cultured mouse bone marrow stromal cells and human promyelocytic leukemia (HL-60) cells.Methods:1. Effects of pre-exposure with microwave onγ-rays induced damages in bone marrow stromal cells. (1) Bone marrow stromal cells were randomly divided into control group, microwave alone group (12μW/cm², 120μW/cm² and 1200μW/cm²), combined exposure group (12μW/cm², 120μW/cm² and 1200μW/cm^<sup>2+8Gyγ-rays) andγ-rays alone group. The microwave alone and combined exposure groups were exposed to microwave,1h a day,for 7 days. The combined exposure andγ-rays alone groups were subsequently exposed to 8Gy 60Coγ-rays on the 8th day. Cell proliferation capacity was measured with cck-8 assay to determine the microwave dose which could most effectively reduceγ-rays-induced damages in bone marrow stromal cells. (2) Bone marrow stromal cells were randomly divided into four groups: control group, microwave alone group (12μW/cm²), combined exposure group (12μW/cm^<sup>2+8Gyγ-rays) andγ-rays alone group. Apoptosis, necrosis and cell cycle were analyzed by flow cytometry; MMP and Ca²⁺ were detected by flow cytometry; Ca²⁺-Mg²⁺-ATPase activity was measured with commercial kits.2. Pre-exposure with microwave onγ-rays induced damages in HL-60 cells. (1) HL-60 cells were randomly divided into control group, microwave alone group (12μW/cm², 120μW/cm² and 1200μW/cm²), combined exposure group (12μW/cm², 120μW/cm² and 1200μW/cm^<sup>2+8Gyγ-rays) andγ-rays alone group. The microwave alone and combined exposure groups were exposed to microwave, 1h a day, for 3 days. The combined exposure andγ-rays alone groups were subsequently exposed to 8Gy 60Coγ-rays on the 4th day. Cell proliferation capacity was measured with cck-8 assay method to determine the microwave power density which could most effectively reduceγ-rays-induced damages in HL-60 cells. (2) HL-60 cells were randomly divided into four groups including control group, microwave alone group (12μW/cm²), combined exposure group (12μW/cm^<sup>2+8Gyγ-rays) andγ-rays alone group. Apoptosis, necrosis and cell cycle were analyzed with flow cytometry; MMP and Ca²⁺ were detected by flow cytometry; Ca²⁺-Mg²⁺-ATPase activity was tested with commercial kits.3. Protective effects of microwave on doxorubicin hydrochloride induced damages in HL-60 cells. (1) HL-60 cells were randomly divided into control group, microwave alone group (12μW/cm², 120μW/cm² and 1200μW/cm²), combined exposure group (12μW/cm², 120μW/cm² and 1200μW/cm^<sup>2+DOX) and DOX alone group. The microwave alone and combined exposure groups were exposed to microwave, 1h a day, for 3 days. The combined exposure and DOX alone groups were subsequently exposed to DOX at concentration of 0.125mg/L on the 4th day. Cell proliferation capacity was measured by cck-8 assay to to define the microwave dose which could most effectively reduce damages induced by doxorubicin hydrochloride. (2) HL-60 cells were randomly divided into control group, microwave alone group (12μW/cm²), combined exposure group (12μW/cm^<sup>2+DOX) and DOX alone group. Apoptosis, necrosis and cell cycle were analyzed by flow cytometry; MMP and Ca²⁺ were detected by flow cytometry; Ca²⁺-Mg²⁺-ATPase activity was measured with commercial kits.Results:1. (1) Compared with control group, cell proliferation activity of 120μW/cm² combined exposure group, 1200μW/cm² combined exposure group andγ-rays alone group significantly decreased(P<0.05). Cell proliferation activity of 12μW/cm² combined exposure group was statistically higher than that of theγ-rays alone group(P<0.05). (2) Compared with control group, apoptosis rate and Ca²⁺ concentration of combined exposure group andγ-rays alone group significantly increased(P<0.05), while MMP and Ca²⁺-Mg²⁺-ATPase activity in both groups statistically decreased(P<0.05), furthermore the percentage of G1 phase cells ofγ-rays alone group significantly increased, as well as percentage of S phase cells in that group significantly decreased(P<0.05). Compared withγ-rays alone group, apoptosis rate and Ca²⁺ concentration of combined exposure group significantly decreased(P<0.05), MMP and Ca²⁺-Mg²⁺-ATPase activity in combined exposure group statistically increased(P<0.05);what is more,the percentage of G1 phase cells of combined exposure group significantly decreased, while the percentage of S phase cells significantly increased(P<0.05).2. (1) Compared with control group, cell proliferation activity of 120μW/cm² microwave alone group, 1200μW/cm² microwave alone group, 120μW/cm² combined exposure group, 1200μW/cm² combined exposure group, andγ-rays alone group significantly decreased(P<0.05). Cell proliferation activity of 12μW/cm² combined exposure group was statistically higher than that of theγ-rays alone group(P<0.05), while cell proliferation activities in the other two combined exposure groups were statistically lower than that of theγ-rays alone group(P<0.05). (2) Compared with control group, apoptosis rate and Ca²⁺ concentration of combined exposure group andγ-rays alone group significantly increased(P<0.05), and Ca²⁺-Mg²⁺-ATPase activity in both groups statistically decreased(P<0.05), while the percentage of G1 and S phase cells of both groups significantly decreased, percentage of G2/M phase cells in these two groups significantly increased(P<0.05), MMP ofγ-rays alone group was statistically lower(P<0.05). Compared withγ-rays alone group, apoptosis rate and Ca²⁺ concentration of combined exposure group significantly decreased(P<0.05), MMP and Ca²⁺-Mg²⁺-ATPase activity in combined exposure group statistically increased(P<0.05), the percentage of G1 and S phase cells in combined exposure group significantly increased, while percentage of G2/M phase cells in that group significantly decreased(P<0.05).3. (1) Compared with control group, cell proliferation activity of all groups except for 12μW/cm² microwave alone group significantly decreased(P<0.05). Cell proliferation activity of 12μW/cm² combined exposure group was statistically higher than that of the DOX alone group(P<0.05), while cell proliferation activities in 120μW/cm² and 1200μW/cm² combined exposure groups were statistically lower than that of the DOX alone group(P<0.05). (2) Compared with control group, apoptosis rate and Ca²⁺ concentration of combined exposure group and DOX alone group significantly increased(P<0.05), while MMP and Ca²⁺-Mg²⁺-ATPase activity in both groups statistically decreased(P<0.05), the percentage of G1 and S phase cells of both groups significantly decreased, percentage of G2/M phase cells in these two groups significantly increased(P<0.05). Compared with DOX alone group, apoptosis rate and Ca²⁺ concentration of combined exposure group significantly decreased(P<0.05), MMP and Ca²⁺-Mg²⁺-ATPase activity in combined exposure group statistically increased(P<0.05), the percentage of G1 and S phase cells in combined exposure group significantly increased while the percentage of G2/M phase cells in that group significantly decreased(P<0.05).Conclusions:1. Pre-exposure with 12μW/cm² low intensity microwave could significantly decrease theγ-rays induced damages of both bone marrow stromal cells and HL-60 cells.2. Pre-exposure with 12μW/cm² low intensity microwave could significantly decrease doxorubicin hydrochloride-induced damages of HL-60 cells.3. Ca²⁺ concentrations decreasing, MMP increasing, and elevating Ca²⁺-Mg²⁺-ATPase activity may be involved in the mechanism that low intensity microwave could alleviate damages induced byγ-rays and doxorubicin hydrochloride.