Photoacoustic detection of circulating melanoma cells in blood

描述（由申请人提供）：黑色素瘤是最致命的皮肤癌，也是所有癌症类型中生长速度最快的一种。在美国，终身风险约为1 / 55，而世界其他地区的风险甚至更大。早期手术切除黑色素瘤是治疗的最佳途径。然而，对于那些病变进展和扩散的病例，监测转移性疾病对于积极的临床结果至关重要。这项提议使用光声学，或激光诱导超声，来检测血液中循环的黑色素瘤细胞（CMC）。这种方法将利用细胞内的自然光吸收剂黑色素，提供一种简单、敏感和无标记的方法来监测转移。在这种方法中，从血液中获得的单个核细胞在类似于流式细胞术的装置中用快速脉冲可调谐激光系统照射。如果全血中存在CMC，它们将驻留在单个核细胞中。虽然单个核细胞不会吸收可见光，但CMC会选择性地吸收光能并成为主动声源，产生瞬态高频压力波，这是CMC的特征。本课题主要关注两个方面：1)改进现有的检测系统；2)利用小鼠黑色素瘤模型研究转移的时间过程及其与CMC存在的关系。为了改进目前的系统，将在改进后的流室中设置一个聚焦声传感器。这一改进将减轻对准困难，减少杂散噪声。使用自动算法的实时小波去噪将被纳入。最后，将纳入一种区分黑色素瘤细胞和红细胞的统计分类方案，从而提高检测的特异性。将研究转移性黑色素瘤小鼠模型，以研究CMC的存在如何与肿瘤负荷和疾病状态相关。将在50只小鼠中诱导转移，并进行micro-CT和micro-PET共登记以监测肿瘤负荷。根据计算出的肿瘤大小，小鼠将被处死并放血，并进行光声测试。本研究将用于设计CMC在人类患者中测试的最佳时间表。监测CMC所提供的信息将用于检测转移、复发、缓解和治疗反应。没有其他系统可以提供这种信息。公共卫生相关性：检测人体血液中的循环肿瘤细胞使临床医生能够观察患者的转移和监测癌症治疗。利用黑色素固有的光学吸收来检测黑色素瘤细胞中激光诱导的声波，将设计一种快速检测这些细胞的系统。该系统在小鼠黑色素瘤模型上的测试结果将用于为人类癌症患者设计最佳测试计划。

DESCRIPTION (provided by applicant): Melanoma is the deadliest form of skin cancer and has the fastest growth rate of all cancer types. In the U.S., the lifetime risk is about 1 in 55, while other parts of the world have even greater risks. Early surgical resection of melanoma is the best avenue of therapy. However, for those cases where the lesion progresses and spreads, monitoring of metastatic disease is crucial for positive clinical outcomes. This proposal uses photoacoustics, or laser induced ultrasound, to detect circulating melanoma cells (CMC's) in blood. This method will exploit the natural light absorber, melanin, within the cells providing a simple, sensitive, and label free means to monitor metastasis. In this method, mononuclear cells obtained from blood are irradiated with a rapid pulsed tunable laser system in a set up similar to flow cytometry. If there are CMC's present in whole blood, they will reside among the mononuclear cells. While a mononuclear cell will not absorb light at visible wavelengths, CMC's will selectively absorb the optical energy and become active acoustic sources, creating transient, high frequency pressure waves that are the signature of CMC's. This proposal has two focus areas: 1) Improve the current detection system, and 2) Use a mouse melanoma model to study the time course of metastasis and its relationship to the presence of CMC's. In order to improve the current system, a focused acoustic sensor will be set within a modified flow chamber. This improvement will mitigate alignment difficulties and decrease spurious noise. Real time wavelet denoising using an automated algorithm will be incorporated. Finally, a statistical classification scheme to discriminate melanoma cells from red blood cells will be incorporated, thus improving specificity of the test. A metastatic melanoma mouse model to study how the presence of CMC's correlate to tumor load and disease state will be studied. Metastasis will be induced in 50 mice and micro-CT coregistered with micro-PET will be performed to monitor tumor load. The mice will be sacrificed and exsanguinated on a schedule determined by calculated tumor size and perform the photoacoustic tests. This research will be used to design optimal schedules for CMC testing in human patients. The information given by monitoring CMC's will be used to detect metastasis, relapse, remission, and response to therapy. No other system is available to offer such information. PUBLIC HEALTH RELEVANCE: Detection of circulating tumor cells in human blood allows clinicians to observe metastasis and monitor cancer therapy in their patients. Using melanins inherent optical absorption to detect laser induced acoustic waves in melanoma cells, a system will be designed for rapid detection of those cells. Results from testing the system on a mouse melanoma model will be used to design an optimal testing plan for human cancer patients.