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The specific membrane capacitance (SMC) of biological cell membranes correlates with cells’ electrical activity and morphology, which are physiological markers for cellular phenotype and health. Conventionally, SMC measurements are conducted using electro-rotation and Patch-clamping, which entail long time training and stringent operation skills. Both techniques also suffer from limited throughput and lengthy measurement time. In this study, a microfluidic device, which enables impedance spectroscopy measurements, was developed to quantify the SMC of single biological cells. The device has a testing speed of approximately one cell per minute and is relatively easy to operate. Three-dimensional finite element simulations of the microfluidic device confirm the feasibility of this approach. SMC measurement of two AML (Acute Myeloid Leukemia) subtypes and two UCC (Urothelium Cell Carcinoma) subtypes were conducted. Measured SMC results were found to lie in the comparable range with previously reported publications.

The specific membrane capacitance (SMC) of biological cell membranes correlates with cells’ electrical activity and morphology, which are physiological markers for cellular phenotype and health. Conventionally, SMC measurements are conducted using electro-rotation and Patch-clamping, which entail long time training and stringent operation skills. Both techniques also suffer from limited throughput and lengthy measurement time. In this study, a microfluidic device, which enables impedance spectroscopy measurements, was developed to quantify the SMC of single biological cells. The device has a testing speed of approximately one cell per minute and is relatively easy to operate. Three-dimensional finite element simulations of the microfluidic device confirm the feasibility of this approach. SMC measurement of two AML (Acute Myeloid Leukemia) subtypes and two UCC (Urothelium Cell Carcinoma) subtypes were conducted. Measured SMC results were found to lie in the comparable range with previously reported publications.

Epithelial membrane protein 2(EMP2), a growth arrest specific-3/peripheral myelin protein-22(GAS3/PMP22) family member, is a tetraspan protein. In prior study identified EMP2 in endometrial cancer was an oncogene, but in B-cell lymphoma was a tumor suppressor gene. The effects of EMP2 on various cancer cell lines precise molecular mechanisms are not clear until now. We observed EMP2 was down-regulated following the progressive grades of bladder cancer cell lines. So, we clone the EMP2 full-length cDNA into the pEGFP-N3 vector as an tool. Then, we overexpressed EMP2 in bladder cancer cell line J82 cells and knockdown EMP2 by shEMP2 in bladder cancer cell line RT4 cells in order to examine its effects on functions of cells like proliferation, cycle , apoptosis and metastasis. Conclusion, we can get cell proliferation of EMP2-overexprssed cells were decreased through arresting G2/M phase of cell cycle. On the other hand, knockdown of EMP2 in RT4 cells increased cell proliferation. Moreover, the ability of migration were decreased by EMP2 in both J82 and RT4 cells.

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Indispensable to all modes of migration used during single cell metastasis, cytoplasmic protrusions are pivotal in surveying cells local surroundings which ultimately initiates migration of the cell body. Cancer cell migration is fairly well studied with the traditional focus on protrusion driven cell body displacement, while less is known on the role of protrusions in sensing cellular microenvironments. Here, we present a suspended and aligned fiber platform capable of high spatio-temporal imaging of protrusions capable of sensing fiber curvature contrasts independent of cell migration. By varying the diameter of suspended fibers, we are able to maintain cell migration along low curvature-large diameter (2μm) fibers, while solely allowing cells to sense, initiate, and mature protrusions on orthogonally deposited high curvature-low diameter (~100, 200 and 600 nm) fibers. Using highly aggressive breast MDA-MB-231 and brain glioblastoma DBTRG-05MG model systems, we find that MDA-MB-231 protrusion maturation dynamics are more sensitive to changes in fiber curvature and fibronectin ligand coating concentration compared to DBTRG-05MG. Furthermore, we find that vimentin intermediate filaments localize within 70% of mature protrusions, which normally form on larger diameter fibers. Additionally, protrusion lengths fluctuate continuously until the protrusion is either terminated or stabilized, and occasionally protrusions are observed to shed cytoplasmic fragments. Through manipulation of curvature contrasts, we demonstrate single protrusive hierarchical decomposition and coordination in zeroth (main), first and second order branches. The fiber curvature platform presented here uniquely allows cancer cells to sense nanofiber curvature contrasts, thus providing new mechanistic insights in protrusion initiation, maturation, and hierarchical coordination. / Master of Science

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