Chemotherapeutic response assessment in cancer cells using a microcavity array-based bioreactor system and sodium triple-quantum MR signal

低的细胞内钠浓度对于细胞活力是至关重要的。化学反应本身表现为诱导细胞凋亡，因此，在细胞内钠和钾浓度的离子逆转，随后凋亡小体形成。钠磁共振（MR）作为一种非侵入性技术，可作为早期治疗反应评估的潜在生物标志物。钠离子与蛋白质的相互作用产生独特的细胞内敏感的三量子（TQ）信号。该TQ信号与灌注心脏中的细胞内钠浓度线性相关，因此代表了量化细胞反应的有吸引力的特征。TQ信号和生物反应器系统的组合特征在于在精细可控的环境中进行器官型3D细胞培养，这使得我们能够在两次Na/K-ATP酶抑制期间监测癌细胞的细胞内钠浓度的变化。因此，我们建议钠TQ信号作为早期治疗反应评估的生物标志物，由于其独特的细胞内敏感性和细胞内钠变化在细胞凋亡过程中的重要性。为了建立这一点，我们将使用钠TQ信号和生物反应器系统的改进设置来监测器官型3D细胞培养物的化学治疗。进一步改进我们提出的固定TQ时间比例相位增量（TQTPPI）脉冲序列将使我们能够定量和快速TQ测量与最高可能的TQ信噪比。因此，我们将评估一种新的重建技术的TQTPPI数据相结合的非相干欠采样技术。通过测定每个细胞的细胞内钠浓度的方法扩展所建立的生物反应器系统将加深我们对化疗治疗期间细胞水平上TQ信号变化的理解。此外，我们将验证在各种Na/K-ATP酶抑制期间TQ信号与细胞内钠浓度的线性相关性，以使用TQ信号量化化疗治疗期间的细胞反应。最后，我们将监测良好表征的大鼠9 L胶质肉瘤细胞系对1，3-双（2-氯乙基）-1-亚硝基脲（BCNU）治疗的化疗反应，使用TQ信号和生物反应器系统的改进设置。BCNU处理大鼠9 L细胞对细胞内钠浓度和单量子MR信号的影响是众所周知的。因此，TQ信号可以被确立为用于早期治疗反应评估的生物标志物。此外，大鼠9 L细胞系和BCNU治疗将允许我们在未来的研究中使用TQ信号研究细胞内低钠浓度对化疗耐药性的至关重要性。我们工作的长期目标是建立TQ信号和生物反应器系统的组合，作为一种新的工具，在一个转化的方法抗癌药物的开发。

A low intracellular sodium concentration is of vital importance for cell viability. Chemotherapeutic response manifests itself in the induction of apoptosis and, thus, in the ionic reversal of intracellular sodium and potassium concentrations followed by apoptotic body formation. Sodium magnetic resonance (MR) as a non-invasive technique can be a potential biomarker for early treatment response assessment. Interactions of sodium ions with proteins create a unique intracellular sensitive triple-quantum (TQ) signal. This TQ signal correlated linearly with the intracellular sodium concentration in perfused hearts and, hence, represents an attractive feature to quantify cellular responses. The combination of TQ signal and bioreactor system featuring an organotypic 3D cell culture in a finely controllable environment allowed us to monitor changes in the intracellular sodium concentration of cancer cells during two Na/K-ATPase inhibitions. Therefore, we propose the sodium TQ signal as a biomarker for early treatment response assessment due to its unique intracellular sensitivity and the importance of intracellular sodium changes during apoptosis. To establish this, we will monitor the chemotherapeutic treatment of organotypic 3D cell cultures using an improved setup of sodium TQ signal and bioreactor system. Further improvements of our proposed fixed TQ time proportional phase incrementation (TQTPPI) pulse sequence will enable us quantitative and fast TQ measurements with the highest possible TQ signal-to-noise ratio. Therefore, we will evaluate a novel reconstruction technique of TQTPPI data combined with incoherent undersampling techniques. Extension of the established bioreactor system by a method for the determination of the intracellular sodium concentration per cell will deepen our understanding of TQ signal changes on a cellular level during chemotherapeutic treatment. In addition, we will verify the linear correlation of TQ signal with intracellular sodium concentration during various Na/K-ATPase inhibitions to quantify cellular responses during chemotherapeutic treatment using the TQ signal. Finally, we will monitor the chemotherapeutic response of the well-characterized rat 9L gliosarcoma cell line to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) treatment using the improved setup of the TQ signal and bioreactor system. The effects of BCNU treatment of rat 9L cells on intracellular sodium concentration and single-quantum MR signal are well known. Hence, the TQ signal can be established as a biomarker for early treatment response assessment. Furthermore, the rat 9L cell line and BCNU treatment will allow us in future studies to investigate the vital importance of a low intracellular sodium concentration on chemotherapeutic resistance using TQ signal. The long-term goal of our work is to establish the combination of TQ signal and bioreactor system as a novel tool for anticancer drug development in a translational approach.