Apoptosis chip for drug screening

This thesis described the process of the development towards a microfluidic platform to perform apoptosis studies on chip in real-time at a single-cell level

Viability analysis and apoptosis induction of breast cancer cells in a microfluidic device: effect of cytostatic drugs

Breast cancer is the leading cause of cancer deaths among non-smoking women worldwide. At the moment the treatment regime is such that patients receive different chemotherapeutic and/or hormonal treatments dependent on the hormone receptor status, the menopausal status and age. However, in vitro sensitivity testing of tumor biopsies could rationalize and improve the choice of chemo- and hormone therapy. Lab-on-a-Chip devices, using microfluidic techniques, make detailed cellular analysis possible using fewer cells, enabling working with a patients’ own cells and performing chemo- and hormone sensitivity testing in an ex vivo setting. This article describes the development of two microfluidic devices made in poly(dimethylsiloxane) (PDMS) to validate the cell culture properties and analyze the chemosensitivity of MCF-7 cells (estrogen receptor positive human breast cancer cells) in response to the drug staurosporine (SSP). In both cases, cell viability was assessed using the life-stain Calcein-AM (CAAM) and the death dye propidium iodide (PI). MCF-7 cells could be statically cultured for up to 7 days in the microfluidic chip. A 30 min flow with SSP and a subsequent 24 h static incubation in the incubator induced apoptosis in MCF-7 cells, as shown by a disappearance of the aggregate-like morphology, a decrease in CAAM staining and an increase in PI staining. This work provides valuable leads to develop a microfluidic chip to test the chemosensitivity of tumor cells in response to therapeutics and in this way improve cancer treatment towards personalized medicine

Nanoscaffold's stiffness affects primary cortical cell network formation

Networks of neurons cultured on-chip can provide insights into both normal and disease-state brain function. The ability to guide neuronal growth in specific, artificially designed patterns allows us to study how brain function follows form. Primary cortical cells cultured on nanograting scaffolds, in particular astrocytes, showed highly ordered regions of dendritic outgrowth. Usually, materials suitable for nanopatterning have a stiffness far above that of the extracellular matrix. In this paper, the authors studied two materials with large differences in stiffness, polydimethylsiloxane (PDMS) and silicon. Our results show that both nanopatterned silicon and PDMS guide the outgrowth of astrocytes in cortical cell culture, but the growth of the astrocyte is affected by the stiffness of the substrate, as revealed by differences in the cell soma size and the organization of the outgrowth

Cancer prevalence in osteoporotic women with low serum vitamin D levels

Objective: The aim of this study was to assess the role of vitamin D in cancer development in postmenopausal osteoporotic women. Methods: A cross-sectional and in vitro study was carried out, with statistical analysis with odds ratios and 95% CIs presented. Human estrogen receptor-positive breast cancer cells (MCF-7) were studied in vitro. The apoptosis-to-proliferation (A/P) ratio was also determined. Results: A total of 885 women were included in this study. Any kind of cancer was found in 112 (12.7%) of all women. Breast cancer was the most prevalent malignancy, representing half of the cases (n = 56, 50%). The prevalence of any kind of cancer and breast cancer in women with low 25-hydroxyvitamin D(3) levels (25OHD; <50 nmol/L) was higher than in women with high 25OHD levels (>= 50 nmol/L). The in vitro study demonstrated a statistically significant increased A/P ratio of 5.27 (95% CI, 4.054-6.493) with a high concentration of 1 alpha, 25-dihydroxyvitamin D (10 mu M) after 96 hours. Conclusions: Osteoporotic women with low serum levels of 25OHD (<50 nmol/L) have an increased prevalence of any kind of cancer and breast cancer; however, these differences are not statistically significant. 1 alpha, 25-dihydroxyvitamin D induced an increased A/P ratio in MCF-7 breast cancer cells in vitro

Analysis of apoptosis on chip - Why the move to chip technology

Apoptosis refers to a specific form of programmed cell death, which guarantees the welfare of the whole organism through the elimination of unwanted cells. The duration of apoptosis is short, involves single cells with morphological changes only after the point of no return, ending with phagocytosis without reaction in the neighbour cell. A number of techniques exist to measure cell death, but we still looking for a simple, specific and sensitive technique which offers the possibility to measure apoptosis on single cell level, without staining, in real time, with high-throughput. The Lab-in-a-Cell concept by using chip technology offers such a tool

Time-resolved high-speed fluorescence imaging of bubble-induced sonoporation.

The uptake of drugs through a cell membrane is enhanced by the use of bubbles and ultrasound. Little is known about the physical mechanisms underlying the uptake at short timescales. Here we study the bubble-assisted uptake of propidium iodide (PI) by endothelial cells at a millisecond timescale using high-speed fluorescence imaging. Single microbubbles were insonified at a driving frequency of 1MHz and at acoustic pressures varying from 200 to 1200 kPa for a duration of 10 and 100 cycles. At a pressure of 200 kPa and 10 cycles, 50% of the cells showed uptake of PI, and this percentage increased to 90% for a pressure of 400 kPa. At a pressure of 1200 kPa all cells showed uptake of PI. The high-speed fluorescence recordings revealed that a localized pore in the cell membrane is formed right at the position of the bubble. Uptake was observed within several milliseconds after insonation and the size of the induced pore was found to be dependent on the bubble radius. Furthermore, the inflow of PI is diffusion-driven. The pore is formed temporarily and closes within several seconds after the ultrasound exposure

Blood-brain barrier (BBB): an overview of the research of the blood-brain barrier using microfluidic devices

The blood-brain barrier (BBB) is a unique feature of the human body, preserving brain homeostasis and preventing toxic substances to enter the brain. However, in various neurodegenerative diseases, the function of the BBB is disturbed. Mechanisms of the breakdown of the BBB are incompletely understood and therefore a realistic model of the BBB is essential. This chapter highlights the anatomy and physiology of the BBB and gives an overview of the current available in vitro models to study the BBB in detail. Proof-of-concept work of BBB-on-Chips are described. Additionally, examples are given to optimize the present devices by engineering the microenvironment to better mimic the in vivo situation. This combination of biomedical science and micro-engineering will generate exciting new results in the field of neurovascular biology

Label-free, high-throughput, electrical detection of cells in droplets

Today, droplet based microfluidics has become a standard platform for high-throughput single cell experimentation and analysis. However, until now no label-free, integrated single cell detection and discrimination method in droplets is available. We present here a microfluidic chip for fast (>100 Hz) and label-free electrical impedance based detection of cells in droplets. The microfluidic glass-PDMS device consists of two main components, the droplet generator and the impedance sensor. The planar electrode pair in the main channel allows the detection of only cells and cell containing droplets passing the electrodes using electrical impedance measurements. At a measurement frequency of 100 kHz nonviable cells, in low-conducting (LC) buffer, show an increase in impedance, due to the resistive effect of the membrane. The opposite effect, an impedance decrease, was observed when a viable cell passed the electrode pair, caused by the presence of the conducting cytoplasm. Moreover, we found that the presence of a viable cell in a droplet also decreased the measured electrical impedance. This impedance change was not visible when a droplet containing a non-viable cell or an empty droplet passed the electrode pair. A non-viable cell in a droplet and an empty droplet were equally classified. Hence, droplets containing (viable) cells can be discriminated from empty droplets. In conclusion, these results provide us with a valuable method to label-free detect and select viable cells in droplets. Furthermore, the proposed method provides the first step towards additional information regarding the encapsulated cells (e.g., size, number, morphology). Moreover, this all-electric approach allows for all-integrated Lab on a Chip (LOC) devices for cell applications using droplet-based platforms

Apoptotic cell death dynamics of HL60 cells studied using a microfluidic cell trap device

This paper presents the design, fabrication and first results of a microfluidic cell trap device for analysis of apoptosis. The microfluidic silicon-glass chip enables the immobilization of cells and real-time monitoring of the apoptotic process. Induction of apoptosis, either electric field mediated or chemically induced with tumour necrosis factor (TNF-), in combination with cycloheximide (CHX), was addressed. Exposure of cells to the appropriate fluorescent dyes, FLICA and PI, allows one to discriminate between viable, apoptotic and necrotic cells. The results showed that the onset of apoptosis and the transitions during the course of the cell death cascade were followed in chemically induced apoptotic HL60 cells. For the case of electric field mediated cell death, the distinction between apoptotic and necrotic stage was not clear. This paper presents the first results to analyse programmed cell death dynamics using this apoptosis chip and a first step towards an integrated apoptosis chip for high-throughput drug screening on a single cellular level