Frank Reidy Research Center for Bioelectrics, Old Dominion University, 4211 Monarch Way, Room 340, Norfolk, VA, 23508, USA.
Vilnius Gediminas Technical University, Vilnius, Lithuania.
Sci Rep. 2022 Feb 2;12(1):1763. doi: 10.1038/s41598-022-04868-x.
Ablation therapies aim at eradication of tumors with minimal impact on surrounding healthy tissues. Conventional pulsed electric field (PEF) treatments cause pain and muscle contractions far beyond the ablation area. The ongoing quest is to identify PEF parameters efficient at ablation but not at stimulation. We measured electroporation and cell killing thresholds for 150 ns-1 ms PEF, uni- and bipolar, delivered in 10- to 300-pulse trains at up to 1 MHz rates. Monolayers of murine colon carcinoma cells exposed to PEF were stained with YO-PRO-1 dye to detect electroporation. In 2-4 h, dead cells were labeled with propidium. Electroporation and cell death thresholds determined by matching the stained areas to the electric field intensity were compared to nerve excitation thresholds (Kim et al. in Int J Mol Sci 22(13):7051, 2021). The minimum fourfold ratio of cell killing and stimulation thresholds was achieved with bipolar nanosecond PEF (nsPEF), a sheer benefit over a 500-fold ratio for conventional 100-µs PEF. Increasing the bipolar nsPEF frequency up to 100 kHz within 10-pulse bursts increased ablation thresholds by < 20%. Restricting such bursts to the refractory period after nerve excitation will minimize the number of neuromuscular reactions while maintaining the ablation efficiency and avoiding heating.
消融疗法旨在最小化对周围健康组织的影响，从而消灭肿瘤。传统的脉冲电场 (PEF) 治疗会引起远超消融区域的疼痛和肌肉收缩。目前的研究目标是确定既能有效消融又不会刺激的 PEF 参数。我们测量了 150ns-1ms 的单极和双极 PEF 在 10-300 个脉冲串，频率高达 1MHz 时的电穿孔和细胞杀伤阈值。用 YO-PRO-1 染料染色暴露于 PEF 的单层鼠结肠癌细胞，以检测电穿孔。在 2-4 小时内，用碘化丙啶标记死亡细胞。通过将染色区域与电场强度匹配来确定电穿孔和细胞死亡阈值，并与神经兴奋阈值进行比较（Kim 等人，《国际分子科学杂志》22(13):7051, 2021）。与传统的 100µs PEF 相比，双极纳秒 PEF（nsPEF）的细胞杀伤和刺激阈值的最小四倍比实现了这一点，这是一个纯粹的优势。在 10 个脉冲串内将双极 nsPEF 频率增加到 100kHz，可将消融阈值提高<20%。将这种脉冲串限制在神经兴奋后的不应期内，将最大限度地减少神经肌肉反应的次数，同时保持消融效率并避免加热。
