Radiolysis, Photolysis and Sonolysis of Cells

工作总结：声动力疗法是一种很有前途的治疗癌症的新方法，它是基于声敏仪和超声波联合杀灭细胞的协同效应。超声波可以深入组织，聚焦在肿瘤的一个小区域，激活无毒分子(如卟啉)，从而将不良副作用降至最低。实验证据表明，声敏化是由于声增敏剂在热塌陷空化泡内部或附近的化学活化，通过敏化剂在水-气界面的直接热解，或由于水的热解形成的氢原子和羟基自由基的反应，形成敏化剂衍生的自由基。来自声波增敏剂的自由基(主要是以碳为中心的)与氧反应生成过氧基和烷氧基。不同于在空化气泡中热解形成的OH自由基和H原子，烷氧基和过氧基与生物介质中的有机化合物的反应性要低得多，因此它们到达临界细胞位置的几率更高。研究了超声(47 KHz)和镓-卟啉类似物(ATX-70)对悬浮在细胞培养介质中的人白血病细胞(HL-525和HL-60)的细胞溶解的协同作用。有机表面活性剂优先在空化气泡的气体/溶液界面聚集并随后分解，产生可扩散到主体溶液的二次自由基。本研究中使用的镓卟啉类似物具有两个n-烷基侧链(ATx-Cx，其中x=碳原子数，范围从x=2到x=12)。通过改变正构烷基链的长度，从而改变ATX-CX衍生物的表面活性，确定了ATX-CX衍生物在空化气泡的气/液界面上积累的细胞杀伤率。在ATX-CX存在下的超声分解后，观察到碳中心自由基产率和细胞杀伤率之间存在很强的相关性。这些结果支持一种假设，即超声和ATX-CX对HL-525和HL-60细胞的协同作用是一种声化学机制。对超声诱导U937细胞凋亡和低渗介质裂解U937细胞的研究支持非致死性低渗可以增强超声诱导的细胞杀伤的假设。偶氮二(2-氨基丙烷)二盐酸盐可增强超声对U937细胞的杀伤作用。这些发现表明，温度依赖的自由基发生器在超声癌症治疗中具有临床潜力。声动力疗法的机制可能不受通用机制的支配，但可能受多种因素的影响，包括生物模型的性质、声敏剂和超声治疗仪。1.Ogawa，R.；Kondo，T.；Mori，H.；赵，Q.L.；Fukuda S.；Riesz，P.：溶解气体对超声介导的体外基因导入的影响。超声声化学，9,197-203,2002.：Feril，L.B.；Kondo，T.；Uemura，S.；Tchibana，K.；Manalo，A.H.；Riesz，P.：声波和抗肿瘤药物：增强联合抗癌治疗的可能性。J·M·超声波(日本)，29,173-187,2002。Sostaric，J.Z.和Riesz，P.：表面活性剂在空化气泡的气体/溶液界面上的吸附：声化学中与超声强度无关的频率效应。J.Phys.化学。B，106,12537-12548,2002.4。Miyoshi，N.；Sostaric，J.Z；Riesz，P.：表面活性剂溶液的声化学与超声波和卟啉对人类白血病细胞杀伤的相关性。自由自在。比奥尔。医学，34,710-719,2003。

Summary of work:Sonodynamic therapy is a promising new modality for cancer treatment based on the synergistic effects of cell killing by a combination of sonosensitzer and ultrasound. Ultrasound can penetrate deeply into tissue and can be focused in a small region of tumor to activate non-toxic molecules (e.g. porphyrins ) thus minimizing undesirable side effects. The experimental evidence suggests that sonosensitization is due to the chemical activation of sonosensitizers inside or in close vicinity of hot collapsing cavitation bubbles to form sensitizer-derived radicals either by direct pyrolysis of the sensitizer at the water-gas interface or due to the reactions of hydrogen atoms and hydroxyl radicals formed by the pyrolysis of water. The free radicals derived from the sonosensitizer (mostly carbon-centered) react with oxygen to form peroxyl and alkoxyl radicals. Unlike OH radicals and H atoms which are formed by pyrolysis inside cavitation bubbles, the reactivity of alkoxyl and peroxyl radicals with organic compounds in biological media is much lower and hence they have a higher probability of reaching critical cellular sites.The synergistic effect of ultrasound (47 kHz) and analogues of gallium-porphyrin derivatives (ATX-70) on cytolysis of human leukemia cells (HL-525 and HL-60) suspended in a cell culture medium were studied. Organic surfactants preferentially accumulate and subsequently decompose at the gas/solution interface of cavitation bubble, producing secondary radicals that can diffuse to the bulk solution. The gallium porphyrin analogues used in the current study possessed two n-alkyl side chains (ATX-Cx, where x = number of carbon atoms, ranging from x = 2 to x = 12). By varying the n-alkyl chain length, thereby modifying the surfactant properties of the ATX-Cx derivatives, cell killing in relation to the accumulation of the ATX-Cx derivatives at the gas/solution interface of cavitation bubbles was determined. Following sonolysis in the presence of the ATX-Cx, a strong correlation for the yield of carbon centered radicals and cell killing was observed. These results support the hypothesis that a sonochemical mechanism is responsible for the synergistic effect of ultrasound and ATX-Cx on HL-525 and HL-60 cells. Studies of the ultrasound-induced apoptosis and lysis of U937 cells by a hypotonic medium support the hypothesis that non-lethal hypotonia can enhance ultrasound-induced cell-killing. Ultrasound-induced killing of U937 cells was enhanced by azobis(2-amidinopropane)dihydrochloride. These findings suggest the clinical potential of temperature-dependent free radical generators in cancer therapy by ultrasound. The mechanism of sonodynamic therapy is probably not governed by a universal mechanism, but may be influenced by multiple factors including the nature of the biological model, the sonosensitizer and the ultrasound prameters.1.Ogawa, R.; Kondo, T.; Mori, H.; Zhao, Q.L.; Fukuda, S.; Riesz, P.: Effects of dissolved gases on ultrasound mediated in vitro gene transfection. Ultrasonics Sonochemistry, 9, 197-203, 2002.2.Feril, L.B.; Kondo, T.; Umemura, S.; Tachibana, K.; Manalo, A.H.; Riesz, P.: Sound waves and antineoplastic drugs: The possibility of an enhanced combined anticancer therapy. J.Med.Ultrasonics(Japan), 29, 173-187, 2002.3.Sostaric, J.Z. and Riesz, P.: Adsorption of surfactants at the gas/solution interface of cavitation bubbles: An ultrasound intensity independent frequency effect in sonochemistry. J. Phys. Chem. B., 106, 12537-12548, 2002.4.Miyoshi, N.; Sostaric, J.Z.; Riesz, P.: Correlation between sonochemistry of surfactant solutions and human leukemia cell killing by ultrasound and porphyrins. Free Rad. Biol. Med., 34, 710-719, 2003.