Microfluidics devices are tiny chips that perform chemical analyses of extremely small volumes of fluids such as blood. Lab-on-a-chip devices, which often use microfluidics, are providing for earlier, more cost-effective disease detection and many other uses, from monitoring to treatment. The global microfluidics market is driven by the demand for low-volume sample analysis and high-throughput screening methodologies and has been fueled by the introduction of advanced technologies, such as lab-on-chip and the demand for in vitro diagnostics (IVDs). The market for microfluidics is expected to boom. This market was valued at $2.2 billion in 2015 and is expected to grow at a CAGR of around 18.3 percent by 2024, according to a report from Grand View Research.

The report notes that the development of point-of-care devices such as the blood sugar testing meters and blood pressure monitoring chips have reduced hospital visits and overall healthcare expenditures as well. This article looks at some of the latest advances in microfluidics and lab-on-a-chip devices and how they are impacting healthcare.

Microfluidic Chip Could Mean Earlier Disease Diagnosis

Proteins are one of the most important classes of biomarkers — biological molecules indicative of a disease or health of an individual. Protein detection is critical in a wide variety of tests that include the diagnosis of malaria, detection of a cardiovascular event, cancer screening and monitoring, and more.

A joint team from Technion and IBM Research in Zurich has improved the sensitivity of protein detection in immunoassays by more than 1,000-fold, when compared to standard immunoas-say implementation. The team's method is based on a simple piece of hardware: a microfluidic chip containing flow channels the width of a human hair.

High sensitivity in detection is particularly important when protein biomarkers are present in extremely small numbers, as is the case in the early stages of a disease. The team's approach might one day enable simple devices capable of analyzing small samples (such as a drop of blood), replacing the large and sophisticated laboratory equipment that is currently required.

“Using a combination of electric fields and specialized chemistry, we collect proteins into a tiny volume and precisely deliver them to react with detection antibodies patterned on the surface of the microchannel,” says Moran Bercovici, assistant professor of the Technion Faculty of Mechanical Engineering.

Blood vessel with no RhoA protein activity keeps its barrier function (left), but when the researchers activated RhoA only in the mural cells, barrier function was lost (right). (Credit: Boston University)

“We essentially cheat the detector,” says Federico Paratore, a joint PhD student between the groups, and the lead author on the work. “We present a protein concentration that is 10,000-fold higher than in the original sample to a standard detector, and get the detector to respond accordingly.”

The test is a simple one. A few drops of the sample are introduced into the microfluidic chip, and an electric field is turned on. The proteins are compressed to a volume of approximately 50 PL — about 1 million times smaller than the volume of a human teardrop, and the result is visible within a few minutes.

“The elegance of this approach is in its simplicity, and of course the immense enhancement in assay sensitivity that could be applied to a range of immunoassay,” says Dr. Govind Kaigala, scientist at IBM Research in Zurich. “We strongly believe such a technology will help to fill the gaps in existing immunoassay technology, and be applied directly to biological samples such as blood, saliva, or urine.”

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Blood Vessel-on-a-Chip Study Reveals Key Proteins’ Regulatory Role in Leaky Vessels

During chronic disease, or even minor injury, blood vessels can be damaged enough to compromise vital organ function. Christopher Chen, director of the Biological Design Center and associate faculty at the Wyss Institute at Harvard University, has built a device to study blood vessel function in a way that closely mimics the real thing.

Chen and his team created a 3D blood vessel-on-a-chip model that can be used to understand what happens to vessels during injury on a molecular scale. “We hope to use these devices to learn more about how to keep vessels healthy, and about what goes awry in disease settings,” he says.

The 3D blood vessel-on-a-chip has allowed Chen and the team to identify specific proteins that regulate vascular barrier function. The researchers studied three proteins — RhoA, Rac 1, and N-cadherin. It has already been well documented that during an inflammatory response, RhoA is activated, so this is where Chen started.

To study barrier function in the vessel-on-a-chip, the researchers introduced molecules that trigger an inflammatory response into the 3D model. Then they could measure activity levels of specific proteins along with how penetrable the vessel became under inflammatory conditions. By measuring both the levels of activity of these three proteins and the vessel barrier function at the same time, they could gauge how each protein's activity affected the barrier.

For example, once inflammation was triggered, RhoA's activity levels increased, which resulted in a loss of barrier function; this was expected. To confirm their result, the researchers inhibited RhoA activity, and barrier function in the vessel was restored. However, when RhoA was targeted to activate only the mural cells, barrier function was lost.

Chen was able to show that a specific balance of these three proteins — RhoA, Rac 1, and N-cadherin — must be sustained in order to preserve the junction between endothelial cells and mural cells. Each one of these proteins plays a different role in maintaining vessel barrier function. Not only do they regulate the protective function endothelial cells provide, but they also affect mural cells — and furthermore regulate how both cell types interact with each other during inflammation. Their results suggest that leaky vessels are caused by a simple inflammatory response, and that they are not the result of complex signaling mechanisms that the literature currently deems the culprit. With the 3D blood vessel-on-a-chip, scientists in a laboratory can study cell-to-cell interactions in vasculature in the most lifelike setting yet.

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Microfluidic Chip Rapidly IDs Deadly Blood Infection

Sepsis biochip showing microfluidic channels that remove red blood cells on the right and the larger chamber of microchip posts on the left that capture the CD64 positive immune cells that are markers for sepsis. (Credit: Rashid Bashir, U. Illinois at Urbana-Champaign.)

Biomedical engineers at the University of Illinois at Urbana – Champaign have developed a rapid test using a single drop of blood for early detection of the deadly blood infection, sepsis. The microfluidic chip could enable early intervention for this life-threatening complication, which accounts for the most deaths and highest medical expenses in hospitals worldwide.

“Patients suspected of having sepsis have a much better clinical outcome when given antibiotics within the first hour,” explains Tiffani Lash, PhD, director of the Point of Care Technologies Research Network (POCTRN), supported by the National Institute of Biomedical Imaging and Bioengineering at NIH. “Therefore, the ability of this biochip to rapidly detect this pervasive and life-threatening condition is an outstanding example of the high impact point-of-care technologies envisioned when POCTRN was created.”

Lash further explains how the POCTRN network supports technology development through all phases including identifying an important clinical need, developing and testing the medical device, commercialization to get it into hospitals, clinics and other health care sites, and training health professionals to properly use the technology.

Normally, sepsis is detected by monitoring patients’ vital signs such as temperature and blood pressure. If these vital signs are abnormal, blood cultures are done to try to identify the type and source of infection to attempt to treat the infection.

“Our strategy focuses on looking at the start of an immune response. The chip detects immune system factors mobilizing in the blood to fight the infection before the patent shows symptoms like a high fever,” says Rashid Bashir, PhD, professor of bioengineering and an associate dean at the Carle Illinois College of Medicine at the University of Illinois, Urbana – Champaign. “Our lab-on-a-chip device detects an increase in white blood cells and a surface marker called CD64 on the surface of a specific type of white blood cell called a neutrophil.”

The team developed the technology to detect CD64 because it is on the surface of the neutrophils that are known to surge in response to infection and cause the organ-damaging inflammation, which is the hallmark of sepsis.

The researchers tested the microchip with anonymous blood samples from patients in the Carle Illinois College of Medicine. Blood was drawn and analyzed with the chip when a patient appeared to be developing a fever. They continued to check the patients’ CD64 levels over time as the clinicians monitored the patients’ vital signs.

The group found that CD64 levels increasing or decreasing correlated with a patient's vital signs getting worse or better, respectively. This first clinical use of the chip was a good indication that the rapid test for CD64 levels appears to be a promising approach for quickly identifying the patients who are most at risk for progressing into sepsis.

Bashir explains that the team is now working to incorporate several additional markers of inflammation into the rapid-test device. This would increase the accuracy of predicting whether a patient is likely to develop sepsis and aid in monitoring a patient's response to treatment. Rapid monitoring of response would allow a patient to switch to a new drug faster if the inflammatory markers indicate the initial treatment is failing.

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Placenta-on-a-Chip: Microsensor Mimics Malaria in the Womb

Though malaria usually cannot be transmitted from mother to baby in utero, both might be affected because malaria-infected red blood cells adhere to blood vessels in the placenta, resulting in about 10,000 maternal and 200,000 newborn deaths annually. Those hit hardest are in developing and subtropical countries, especially in sub-Saharan Africa.

Artists rendition showing green antibodies to CD64 on microchip posts. The yellow immune cells with CD64 on the surface (pink) are captured by the antibodies. Immune cells without CD64 flow through the device and are not captured by the antibodies. (Credit: Rashid Bashir, University of Illinois at Urbana – Champaign.)

Researchers from Florida Atlantic University are developing a 3D model that uses a single microfluidic sensing chip to study the complicated processes that take place in malaria-infected placenta as well as other placenta-related diseases and pathologies. The technology will mimic the microenvironment of placental malaria, specifically the maternal-fetal interface.

“There are a number of challenges in studying the biology of the human placenta in its natural form or in situ because of ethical reasons as well as accessibility,” says Sarah Du, PhD, principal investigator of the grant and an assistant professor in the Department of Ocean and Mechanical Engineering in FAU's College of Engineering and Computer Science.

Du, together with grant multi-principal investigator, Andrew Oleinikov, PhD, associate professor of biomedical science in FAU's Charles E. Schmidt College of Medicine, came up with the idea of developing a placenta-on-a-chip device using embedded microsensors. They are designing this device to provide real-time monitoring of vascular cell well-being and nutrient circulation across the barrier between mother and fetus, and under the influences of die malaria parasite to see how it responds to various drug treatments.

Placenta-on-a-chip will be able to simulate actual blood flow in vitro and mimic the microenvironment of the malaria-infected placenta in this flow condition. Researchers will be able to closely examine the process that takes place as the infected red blood cells interact with the placental vasculature and to identify interventions that reverse parasite-infected erythrocyte adhesion that is found in placental tissue.

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‘Labyrinth’ Chip Could Help Monitor Aggressive Cancer Stem Cells

The labyrinth chip could one day help doctors look for aggressive, stem-like cancer cells in patient blood. (Credit: Joseph Xu, Michigan Engineering Communications & Marketing)

Inspired by the Labyrinth of Greek mythology, a new chip etched with fluid channels sends blood samples through a hydrodynamic maze to separate out rare circulating cancer cells into a relatively clean stream for analysis. It is already in use in a breast cancer clinical trial.

Tumor cells isolated from blood samples have the potential to revolutionize cancer treatment by enabling doctors to plan customized treatments, monitor genetic changes, and flag the presence of aggressive cells that are likely to spread the cancer. The trouble is that circulating cancer cells account for just one in a billion blood cells, and there weren't good options for accurately capturing cancer stem cells, which are thought to be especially aggressive and drug resistant.

“You cannot put a box around these cells,” says Sunitha Nagrath, University of Michigan associate professor of chemical engineering, who led the development of the chip along with Max Wicha, the Madeline and Sidney Forbes Professor of Oncology at Michigan Medicine. Wicha is one of the pioneers of the cancer stem cell hypothesis.

Cancer stem cells are fluid in their gene expression, transitioning from stem-like cells that are good at surviving in the blood to more ordinary cell types that are better at growing and dividing. Conventional cell targeting, by grabbing proteins known to be on the cell's surface, doesn't work well.

Size-based sorting gets around this problem, but until the labyrinth, this technique was too imprecise to use on its own. Conventional chips, with spiral-shaped channels, left each cancer cell contaminated with thousands of other cells — particularly white blood cells.

The labyrinth riffs on the spiral, sorting the blood's contents according to the sizes of the cells, with smaller white and red blood cells accumulating in different parts of the fluid channel. A number of forces are at play: on the inside of a curve, eddies push particles away from the wall. The larger cancer cells are pushed a bit harder than the smaller white blood cells. At the outside of the curve, smaller particles feel more drawn to the wall.

But the innovation of the labyrinth is its daring number of corners. The tortuous route also meant that Eric Lin, U-M doctoral student in chemical engineering and first author on the paper in Cell Systems, was able to fit 60 cm of channel on a chip that would only contain 10 cm in a spiral layout.

Moreover, without the need to wait for cancer cells to bind with traps or markers, the blood flow through the chip was very fast. The team could reduce the number of white blood cells contaminating the cancer cell sample by 10 times just by running the captured portion of the blood through a second labyrinth chip — a process that took only five extra minutes.

A clinical trial is investigating whether a treatment blocking an immune signaling molecule called interleukin-6, which helps heal wounds by temporarily activating adult stem cells, can make progress against cases of breast cancer that don't respond to standard treatments. The suspicion is that the inter-leukin-6 is enabling cancer stem cells, so they expect to see the population of stem-like cells in the blood fall during treatment.

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