PDF(Pubmed)
Abstract：
Radiation delivery at ultrahigh dose rates (UHDRs) has potential for use as a new anticancer therapeutic strategy. The FLASH effect induced by UHDR irradiation has been shown to maintain antitumour efficacy with a reduction in normal tissue toxicity; however, the FLASH effect has been difficult to demonstrate in vitro. The objective to demonstrate the FLASH effect in vitro is challenging, aiming to reveal a differential response between cancer and normal cells to further identify cell molecular mechanisms. New high-intensity petawatt laser-driven accelerators can deliver very high-energy electrons (VHEEs) at dose rates as high as 1013 Gy/s in very short pulses (10-13 s). Here, we present the first in vitro experiments carried out on cancer cells and normal non-transformed cells concurrently exposed to laser-plasma accelerated (LPA) electrons. Specifically, melanoma cancer cells and normal melanocyte co-cultures grown on chamber slides were simultaneously irradiated with LPA electrons. A non-uniform dose distribution on the cell cultures was revealed by Gafchromic films placed behind the chamber slide supporting the cells. In parallel experiments, cell co-cultures were exposed to pulsed X-ray irradiation, which served as positive controls for radiation-induced nuclear DNA double-strand breaks. By measuring the impact on discrete areas of the cell monolayers, the greatest proportion of the damaged DNA-containing nuclei was attained by the LPA electrons at a cumulative dose one order of magnitude lower than the dose obtained by pulsed X-ray irradiation. Interestingly, in certain discrete areas, we observed that LPA electron exposure had a different effect on the DNA damage in healthy normal human epidermal melanocyte (NHEM) cells than in A375 melanoma cells; here, the normal cells were less affected by the LPA exposure than cancer cells. This result is the first in vitro demonstration of a differential response of tumour and normal cells exposed to FLASH irradiation and may contribute to the development of new cell culture strategies to explore fundamental understanding of FLASH-induced cell effect.
摘要：
超高剂量率（UHDR）的辐射递送有可能用作新的抗癌治疗策略。UHDR辐射诱导的FLASH效应已被证明可以维持抗肿瘤功效，同时降低正常组织毒性；然而，在体外很难证明FLASH效应。证明体外FLASH效应的目标是具有挑战性的，旨在揭示癌细胞和正常细胞之间的差异反应，以进一步确定细胞分子机制。新型高强度petawatt激光驱动加速器可以在非常短的脉冲（10-13s）中以高达1013Gy/s的剂量率传递非常高能量的电子（VHEE）。这里,我们介绍了在同时暴露于激光等离子体加速（LPA）电子的癌细胞和正常非转化细胞上进行的第一个体外实验。具体来说,同时用LPA电子照射在腔载玻片上生长的黑色素瘤癌细胞和正常黑素细胞共培养物。通过放置在支撑细胞的室载玻片后面的Gafchrom膜揭示了细胞培养物上的不均匀剂量分布。在平行实验中,细胞共培养物暴露于脉冲X射线照射，作为辐射诱导的核DNA双链断裂的阳性对照。通过测量对细胞单层离散区域的影响，LPA电子的累积剂量比脉冲X射线辐射获得的剂量低一个数量级，从而获得了最大比例的含受损DNA核。有趣的是,在某些离散区域，我们观察到LPA电子暴露对健康正常人表皮黑素细胞（NHEM）细胞的DNA损伤的影响不同于A375黑色素瘤细胞；与癌细胞相比，正常细胞受LPA暴露的影响较小。此结果是首次在体外证明暴露于FLASH辐射的肿瘤和正常细胞的差异反应，并且可能有助于开发新的细胞培养策略，以探索对FLASH诱导的细胞效应的基本理解。
