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CTCs have emerged as a potential source of clinical significance. But with numerous isolating systems currently available, the numbers of captured CTCs vary widely. At this point, CellSearch remains the only FDA-approved system with clinical significance whereby the results could be used to monitor patients with metastatic colon, breast, or prostate cancer. However, its inability to isolate CTCs from non-high risk prostate cancer patients or CTCs that are EpCAM-negative has led to criticism. In this study, we have shown that size-based filtration successfully isolates CTCs from patients with localized and metastatic prostate cancer. We have also shown that CTCs can be successfully isolated from low and intermediate risk groups. Additionally, clusters of CTCs were preserved and isolated in all localized risk groups and metastatic patients. Furthermore, we enumerated the isolated CTCs using automated and manual methods in low risk, intermediate risk, high risk, and metastatic prostate cancer. The automated and manual counts were comparable. Moreover, the amounts of clusters and the size of clusters correlated with the status and stage of prostate cancer. / October 2016

Circulating tumor cells (CTCs) are the cells that are shed from a primary tumor into the vasculature and circulate in the bloodstream. CTCs may trigger cancer metastasis, which leads to most cancer-related deaths. CTCs are widely studied due to their value in cancer diagnosis, prognosis, and oncology studies. The major challenges with CTCs lie in their extremely low concentration in blood, thus requiring an effective enriching system to enable downstream analyses. The immunomagnetic assay has proved to be a promising CTC detection tool with high sensitivity and throughput. Key factors related to the immunomagnetic assay include the capture rate, which indicates the sensitivity, and distributions of target cells after capture, which impact the cell integrity and other biological properties. In this dissertation, we build a sedimentation model, a partial viscosity model, and a cell-tracking model to address the principle of the immunomagnetic cell separation. We examine the channel orientations and determine the favorable inverted condition. In addition, we develop a micromagnet approach to modulate the in-channel magnetic field toward enhanced cell detection and distribution. Through numerical studies, we calculate the magnetic field generated by the thin-film micromagnets, determine its effective ranges, and demonstrate its value in optimizing cell distribution. In the experimental demonstration, we present two types of micromagnets based on e-beam Ni deposition and inkjet printing technology, respectively. In the screening experiments, the Ni micromagnet integrated system achieves over 97% capture rate. It shows a 14% increase in capture rate, and a 14% improvement in distribution uniformity compared with plain slides. We also successfully isolate CTCs from metastatic cancer patients with the micromagnet assay. The inkjet-printed patterns yield a similarly high capture rate of 103%. With the pixel permanent magnet array, the inkjet patterns further increase the distribution uniformity for 20%. The proposed models lay the theoretical foundations for future modification of the immunomagnetic assay, and the micromagnet-integrated system provides a promising tool for translational applications in cancer diagnose and clinical cancer management. / text

The attachment and detachment of circulating tumor cells in a functionalized microchannel under hydrodynamic loading have been studied. For the cell attachment experiments, EpCAM antibodies are immobilized on the microchannel surface to capture either PC3N prostate or MDA-MB-231 breast cancer cells from homogeneous cell suspensions. Using the same protocol, N-Cadherin antibodies are immoblilzed and used to study the detachment of target cancer cells captured in the microchannels.A critical flow rate Qc has been identified to characterize the kinetics of cell capture in a functionalized microchannel. Approaching one limit, when the receptor-ligand interaction dominates, more than 90% of moving cells can be captured and a sharp peak is observed in the spatial distribution of the captured cells. Approaching another limit, when hydrodynamic loading dominates, almost all cells cannot be captured in the channel. Between these two limits, there is a transition region in which both capture efficiency and cell distribution are sensitive to the flow parameters. Proper characteristic time and length scales have been identified to describe the cell spatial distribution using a log-normal statistical model. The kinetic details of cell capture are determined by the competition between the flow rate and the ligand-receptor association/dissociation rates.Additionally, the attachment dynamics of circulating tumor cells in a bio-functionalized microchannel under hydrodynamic loading has been explored. The target cells initially role along the microchannel with fluctuating velocity prior to firm adhesion. When a successful bond is established, the cancer cells require a certain length to come to a complete stop; this stopping length is found to depend linearly on the applied hydrodynamic flow rate. The force balance in the vertical cross stream direction is dominated by the gravitational force; as a result, all cells loaded into a microchannel intimately contact the functionalized channel bottom surface within a short time. The streamwise horizontal motion of the cells on the surface is dominated by the balance between the shear flow hydrodynamic loading and the receptor-ligand binding interaction. A linear spring element is incorporated in the physical model to represent the dynamics of a cancer cell captured by immobilized antibodies. Featuring a mobility matrix, a proposed theoretical model is utilized to estimate the binding and hydrodynamic forces acting on the cell in a microchannel. Inserting certain fitting parameters, the time evolution of a stopping cell is successfully predicted by a simplified exponential function.The mechanical response of a captured cancer cell to a hydrodynamic flow field is investigated and, in particular, the effect of flow acceleration is examined. The observed cell deformation is dramatic under low acceleration, but is negligible under high acceleration. Consequently, the detachment of captured cells depends on both flow rate and flow acceleration. The flow rate required for cell detachment is a random variable that can be described by a log-normal distribution. Two flow acceleration limits have been identified for proper scaling of the flow rate required to detach captured cells. A time constant on the order of 1min for the mechanical response of a captured cell has been identified for scaling the flow acceleration. Based on these acceleration limits and the time constant, an exponential-like empirical model is proposed to predict the flow rate required for cell detachment as a function of flow acceleration.

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This work focuses on the integration of microfluidics and dielectrophoresis(DEP) with the principles of field flow fractionation (FFF) to create a continuous-flow isolator for rare and viable circulating tumor cells (CTCs) from peripheral blood mononuclear cells (PBMNs) drawn from cancer patients. The method exploits differences in the plasma membrane capacitances of tumor and blood cells, which correspond to differences in the membrane surface areas of these cell types. DEP-FFF was first adapted to measure cell membrane capacitance, cell density and deformability profiles of cell populations. These properties of the NCI-60 panel of cancer cell types, which represents the wide functional diversity of cancers from 9 organs and leukemia, were compared with the normal cell subpopulations of peripheral blood. In every case, the NCI-60 cells exhibited membrane capacitance characteristics that were distinct from blood and, as a result, they could be isolated from blood by DEP. The heightened cancer cell membrane capacitances correlated strongly with membrane-rich morphological characteristics at their growth sites, including cell flattening, dendritic projections, and surface wrinkling. Following harvest from culture and maintenance in suspension, cancer cells were found to shed cytoplasm and membrane area over time and the suspended cell populations developed considerable morphological diversity. The shedding changed the cancer cell DEP properties but they could still be isolated from blood cells. A similar shedding process in the peripheral blood could account for the surprisingly wide morphological diversity seen among circulating cells isolated from clinical specimens. A continuous flow DEP-FFF method was devised to exploit these findings by allowing CTCs to be isolated from the nucleated cells of 10 mL clinical blood specimens in 40 minutes, an extremely high throughput rate for a microfluidic-based method. Cultured cancer cells could be isolated at 70-80% efficiency using this approach and the isolation of CTCs from clinical specimens was demonstrated. The results showed that the continuous DEP-FFF method delivers unmodified, viable CTCs for analysis, is perhaps universally applicable to isolation of CTCs from different cancer types and is independent of surface antigens - making it suitable for cells lacking the epithelial markers used in currently accepted CTC isolation methods. / text

Attachment of circulating tumor cells in microfluidic devices functionalized with proper antibodies was studied. Under static experimental conditions, microchambers were utilized to study the parameters such as cell suspension concentration, incubation time or ambient temperature that may affect the binding of cell to the functionalized surfaces. Specific capture of cells from suspensions increases exponentially with incubation time and linearly with concentration within the tested range. Functionalizing a surface with counter-receptors enables capture of almost 100% of cells within 15 minutes incubation time at ambient temperature higher than 25°C. Suspending cells with different receptors, changing the counter receptors immobilized on the surface, or incubation the cell suspension at low ambient temperature result in a poor capture ratio. To illustrate the specific binding of target cells, various binary mixtures of target cancer and blood cells were incubated in the microchambers. The microsystem sensitivity, specificity and accuracy were determined as a function of the incubated cell concentrations. In general, the system specificity increases while the sensitivity decreases with increasing cell concentration; the accuracy of the system depends weakly on cell concentration within the tested range. The cell attachment dynamics in shear flow was studied by driving the MDA-MB- 231 or BT-20 cells through microchannels functionalized with EpCAM antibodies. The cell attachment ratio was experimentally determined at different flow rates. A modeling system based on Stokesian as well as cell-adhesive dynamics is adopted to analyze the cell motion. The cell motion is modeled as a rigid sphere, with receptors on its surface, moving under shear flow above a surface immobilized with ligands. The system is described mathematically by the Langevin equation, in which the receptor-ligand bonds are modeled as linear springs. Primarily depending on the applied flow rate, three distinct dynamic states of cell motion have been observed: free motion, rolling adhesion, and firm adhesion. The fraction of cells captured due to firm adhesion, defined as attachment ratio, depends on the applied flow rate with a characteristic value that increases with either cellreceptor or surface-ligand density. Utilizing this characteristic flow rate as a scaling parameter, all measured and calculated attachment ratios for different receptor and ligand densities collapse onto a single exponential curve. Binary mixtures of target MDA-MB-231 cells and non-target BT-20 cells were driven through anti-cadherin-11 functionalized microchannels to study the selective isoaltion of target cells from binary mixtures. The system sensitivity is very high, above 0.95, while the specificity is only moderately high, about 0.85, essentially independent of the relative concentration of the target and non-target cells in the binary mixture. An attachment/detachment flow field pattern is proposed to enhance the system specificity. Utilizing this flow pattern with a 1:1,000 MDA-MB-231:BT-20 binary cell mixture, the microfluidic system specificity increased to about 0.95 while the sensitivity remained above 0.95. In order to obtain high experimental throughput allowing lower relative concentration of target cells, a microchannel array which enables processing samples containing about 510⁵ cells with a minimum target cell concentration ratio of 1/100,000 was designed and fabricated. To demonstrate selective isolation of target cells, binary mixtures of BT-20 cells and MIA PaCa-2 cells were driven through microchannel arrays functionalized with EpCAM antibodies; the EpCAM positive BT-20 cells served as target cells and the EpCAM negative MIA PaCa-2 cells as non-target cells. The relative concentration ratio of target/non-target cells varied from 1:1 to 1:100,000. The sensitivity was close to 1.0 while the specificity was also high, about 0.95. The additional detachment step, with a faster flow rate, enhanced the specificity to about 0.985. Initial results of two sets of experiments are reported as preliminary studies for future work. In the first set of experiments, whole blood samples from healthy donors were spiked with a known number of BT-20 cells at a concentration of 500 CTCs per milliliter blood or 50 CTCs per milliliter blood. After a pretreatment to enrich the CTCs, the samples were driven through microchannel arrays functionalized with anti-EpCAM. For both samples, around 55% of the target CTCs were captured in the microchannel arrays. The second set of experiments was dedicated to characterization of target cells exposed to applied shear stress. BT-20 or MDA-MB-231 cells were driven through microchannels functionalized with EpCAM antibodies to allow target cell attachment; then, a high flow rate was applied to detach the captured cells. The detached cells were collected and cultured in an incubator to test their viability. For both cell lines, the majority of the captured CTCs collected from the microchannels were viable. The images taken after three and seven days of culture demonstrate continuous cell growth and division.

Orientador: Adriana Polachini Valle / Resumo: Introdução: O câncer de próstata (CP) é o mais incidente entre os homens em todas as regiões do Brasil. A detecção e caracterização de células tumorais circulantes (CTCs) tem sido apontada como uma alternativa para melhor compreensão da biologia dos tumores, incluindo câncer de próstata. Objetivo: Este estudo tem como objetivo avaliar a detecção de CTCs em pacientes com tumor de próstata localizado e metastático por teste rápido de filtração celular. Metodologia: Foram incluídos pacientes com diagnóstico anatomopatológico de câncer de próstata ou neoplasia intraepitelial prostática. Os dados demográficos, laudos anatomopatológicos e de Cintilografia Óssea e valores do antígeno prostático especifico ( PSA) foram obtidos pelo estudo dos prontuários médicos dos pacientes. Os pacientes foram classificados como portadores de tumor metastático quando apresentavam evidência de imagem metastática pela Cintilografia Óssea. As CTS foram isoladas por teste rápido de filtração celular com posterior imunocitoquímica utilizando-se anticorpos monoclonais anti-PSA para caracterização câncer de próstata específica das células. Resultados: As CTCs foram detectadas em 9 dos 21 pacientes (43%) com positividade de 60% no grupo metastático e 36% no grupo de tumor localizado. Não foram observadas associações entre os valores de PSA e tratamento instituído com a detecção de CTCS. Discussão: A positividade das CTCs no presente estudo mostrou-se semelhante aos dados da literatura, embora possam ser ci... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: Prostate cancer (PC) is the most frequent among men in all regions of Brazil. The detection and characterization of circulating tumor cells (CTCs) has been pointed out as an alternative for a better understanding of the biology of tumors, including prostate cancer. Objective: This study aims to evaluate the detection of CTCs in patients with localized and metastatic prostate tumor by rapid cell filtration test. Methodology: Patients with anatomopathological diagnosis of prostate cancer or prostatic intraepithelial neoplasia were included. Demographic data, anatomopathological and bone scintigraphy reports and prostate specific antigen (PSA) values were obtained by the study of patients' medical records. Patients were classified as having metastatic tumor when they presented evidence of metastatic image by Bone Scintigraphy. The CTS were isolated by rapid cell filtration test with subsequent immunocytochemistry using anti-PSA monoclonal antibodies for cell-specific prostate cancer characterization. Results: CTCs were detected in 9 of the 21 patients (43%) with 60% positivity in the metastatic group and 36% in the localized tumor group. No associations were observed between PSA values and treatment established with CTCS detection. Discussion: The positivity of the CTCs in the present study was similar to the data in the literature, although some limitations of the study may be cited, such as a small number of patients included, difficulties encountered by research... (Complete abstract click electronic access below) / Mestre

Circulating tumor cells (CTCs) represent a systemic phase of the localised cancer disease. They can be distinguished and enriched from the peripheral blood and so from the surrounding leukocytes by either physical properties (e.g., density and size) or biological properties (e.g., expression of epithelial proteins such as EpCAM or cytokeratins) and are usually further characterized by immunostaining or RT-PCR assays. Selecting patients with the risk of disease relaps at the time of diagnosis is crucial for clinicians in deciding who should, and who should not, receive adjuvant chemotherapy. We know that CTCs are strong prognostic factor in patients with metastatic as well as localized breast cancer (BC). It is also known that the prognostic power of circulating tumor cells in women with BC is independent from the standard prognostic indicators. Testing of CTCs known recently as "liquid biopsy" could be informative not only as predictor of the disease relapse, but also as the predictor of therapy effectiveness. The clinical use of CTCs must be strictly encouraged by clinical trials results. Monitoring of CTCs in time could zoom in the mechanism of therapy resistance and/or may provide the identification of new druggable targets. The purpose of my work was therefore to assess the CTCs positivity rate...

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