Photoacoustic detection of circulating melanoma cells in blood

描述（由申请人提供）：黑色素瘤是皮肤癌中最致命的一种，在所有癌症类型中生长速度最快。在美国，终生患病的风险约为五十五分之一，而世界其他地区的风险甚至更大。早期手术切除是治疗黑色素瘤的最佳途径。然而，对于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局至关重要。该提议使用光声或激光诱导的超声来检测血液中的循环黑素瘤细胞（CMC）。该方法将利用细胞内的自然光吸收剂黑色素，提供简单、灵敏和无标记的手段来监测转移。在该方法中，在类似于流式细胞术的设置中，用快速脉冲可调谐激光系统照射从血液中获得的单核细胞。如果在全血中存在CMC，它们将驻留在单核细胞中。虽然单核细胞不会吸收可见波长的光，但CMC将选择性地吸收光能并成为有源声源，产生瞬态高频压力波，这是CMC的特征。该建议有两个重点领域：1）改进当前的检测系统，和2）使用小鼠黑素瘤模型来研究转移的时间过程及其与CMC存在的关系。为了改进当前的系统，将在改进的流室内设置聚焦声学传感器。这种改进将减轻对准困难并减少寄生噪声。将采用自动算法进行真实的时间小波去噪。最后，将纳入区分黑色素瘤细胞和红细胞的统计分类方案，从而提高测试的特异性。将研究转移性黑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，并将进行与micro-PET共配准的micro-CT以监测肿瘤负荷。按照计算的肿瘤大小确定的时间表处死小鼠并放血，并进行光声试验。这项研究将用于设计在人类患者中进行CMC测试的最佳时间表。通过监测CMC提供的信息将用于检测转移、复发、缓解和对治疗的反应。没有其他系统可以提供此类信息。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转移并监测患者的癌症治疗。利用黑色素固有的光吸收来检测黑色素瘤细胞中的激光诱导声波，将设计用于快速检测这些细胞的系统。在小鼠黑色素瘤模型上测试该系统的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.