|Global Health: Putting Passion to Work with Novel Point-of-Care Diagnostics|
"I'm passionate about global health, about my own research to develop technologies for use in resource-limited settings, as well as the work that others are doing to improve the lives of people in developing countries," says Peter Lillehoj, Ph.D., of Michigan State University in East Lansing. That passion motivated Lillehoj to serve as guest editor of a 2014 special issue of the Journal of Laboratory Automation (JALA) on New Developments in Global Health Technologies.
Yet underserved populations are not the only ones who will benefit, Lillehoj observes. "Much of the research in these areas will have universal application. The same technologies that could be used to identify neglected diseases in the developing world could be applied to diagnose infections, cancers and hereditary diseases, for example, in developed countries."
Biosensors and Wearable Sensors
Lillehoj and his colleagues currently are working on two global health-related projects, one of which clearly will benefit rural and remote communities everywhere and another that has more immediate implications for the United States and other developed nations. As a Ph.D. student in mechanical engineering, Lillehoj and his advisor at the time, Chih-Ming Ho of UCLA (who also happens to be the father of JALA Editor-in-Chief Dean Ho!), received a $100,000 Grand Challenges Exploration grant from the Bill and Melinda Gates Foundation to develop a mobile phone malaria biosensor based on SIM (Subscriber Identity Module) card platform (a SIM card is a memory chip used in most cell phones).
The difference between Lillehoj's technology and other point-of-care malaria diagnostics is that his device will be able to provide quantitative results, "not just a positive or negative," he says. "In particular, knowing the concentration of malaria biomarkers is important for diagnosing and triaging cerebral malaria, which is especially fatal in children. Right now, if you want that kind of detailed quantification, you need to use an ELISA assay, which is impractical for use in remote areas. A portable, cell phone-based instrument that can give you those quantitative results could be life saving."
Lillehoj's other project, for which he recently received a five-year, $400,000 National Science Foundation CAREER Award, involves developing wearable sensors for the detection of influenza, urinary tract infections (UTI) and other conditions by measuring biomarkers secreted in bodily fluids such as sweat and urine. Currently, wearable sensors are limited to measuring vital signs, he notes, but few are aimed at biomolecular detection.
For UTI detection, Lillehoj envisions a biosensor integrated into a disposable diaper or garment that older adults—the group most affected—might already be wearing. "For the broader application of influenza detection, which affects everyone, no matter which part of the world you live in, we'd be looking to integrate sensors into a shirt, socks or wristband that could potentially be reused," he explains. "So in the future, you might be able to go to a pharmacy and buy a disposable biosensor that would be similar to a pregnancy test except it detects viral infections, such as the flu. You'd wear it and after a certain amount of time, it would give you a result. At least for now, such devices would not provide a definitive diagnosis; rather, they would indicate whether you have nothing to worry about or if you should see a doctor for further testing. But eventually, the technology might become so advanced that it could provide results that are as accurate as conventional lab tests."
Macdara Glynn, Ph.D., a postdoctoral researcher with Jens Ducrée in the Microfluidic Platforms Group at the Biomedical Diagnostics Institute at Dublin City University, Ireland, and colleagues also are striving to bring diagnostics to the point of care, rather than relying on lab tests. In the special issue of JALA, the group reports on an Enterprise Ireland-funded HIV diagnostic system specifically for use in sub-Saharan Africa, where the AIDS pandemic is largely concentrated today.
"We know that HIV diagnostics is quite routine if you have a well equipped hospital, but it's another thing in resource-poor regions that don't have access to devices such as a flow cytometer to do the testing," Glynn says. "The idea of our project was not to just develop another test for CD4 [the biomarker for HIV], but to develop a test that is realistic, portable and cheap."
The team's diagnostic device uses a CD-like disc as a centrifugal microfluidics platform. "Essentially, we take blood straight out of a vein and tag the CD4 cells with tiny magnetic beads. Then we apply two forces to that blood. We spin the CD disc, just like a merry-go-round, so all the cells, including the magnetic cells, feel the centrifugal force going outwards towards the edge of the disc, just the way you'd feel it on a merry-go-around if you're about to be thrown off," Glynn explains.
"But perpendicular to that, going at 90 degrees to the direction of the centrifugal force, we have a magnetic force. Only the magnetic CD4 cells would experience both forces, whereas all the background cells (i.e., nonmagnetized red blood cells) experience only the centrifugal force. So we have two forces going in different directions, which we call a 'dual force separation,' and that lets us easily separate out the two cell populations." At that point, the concentrations of CD4 cells can be measured, potentially enabling both rapid diagnostics and/or monitoring of a treatment regimen's impact.
The system currently is in the prototype stage, Glynn says. "The main bottleneck is the time it takes to spin the disc. We need a balance between how fast we spin it and how strong the magnet has to be; the perfect balance point will give us a realistic time on a diagnostic output," he explains. During recent testing, it took between 25-45 minutes to get a result from finger prick blood.
Thinking ahead, the team created a small device to run the disc using an in-house 3D printer at a total cost of about €5. The next step is to see how well the system does with HIV+ blood. The researchers will be collaborating with a local hospital or HIV clinic to test patient-derived samples and validate the system. A similar device was used by a Charles Nwankire, a post doctoral researcher in the lab, for liver function screening in an HIV clinic in Nigeria, Glynn notes. The liver assay panel provided results in less than 20 minutes, using only a tenth of the reagent volumes used in standard hospital laboratory tests, "thereby demonstrating its application to point-of-care testing," he says.
Glynn emphasizes that the team's work would not have been possible without cross-discipline training and collaboration. A cell biologist with a Ph.D. in biochemistry, Glynn was hired by StokesBio (a University of Limerick, Ireland, spinout company that was subsequently acquired by Life Technologies) specifically to work with microfluidic and mechanical engineers to "integrate biology into a massive, very high-throughput instrument for qPCR," he says. Glynn and engineering colleague David Kinahan then joined the Dublin City University lab of Ducrée. "Professor Ducrée was looking for a biologist with engineering experience and an engineer with biological experience, so we fit into that straightaway."
Cell Phone-Based Antimicrobial Susceptibility Testing
Pak Kin Wong, Ph.D., associate professor in the departments of aerospace and mechanical engineering, agricultural and biosystems engineering, and biomedical engineering and the BIO5 Institute at the University of Arizona in Tucson and colleagues report in the special issue on a cell phone-based diagnostic system for antimicrobial susceptibility testing in resource-limited settings.
The team is particularly concerned about the spread of multidrug-resistant pathogens, and a new report from the World Health Organization suggests those concerns are well founded. "To get an accurate diagnosis of an ill patient, a doctor normally has to take a sample and send it to a centralized facility for culturing. There's a two- or three-day wait before they know what bacteria may be causing the problem and what drugs those bugs might be resistant to," Wong says. "No one wants to wait several days to be treated for infection, especially in remote or low-resource settings, so clinicians generally assume a worst-case scenario and prescribe a strong, broad-spectrum antibiotic. The more these 'big guns' are used, the more likely it is that bacteria will develop resistance to them." The pharmaceutical industry is reluctant to invest in developing new drugs that could become useless in a few years, "so we have fewer antibiotics being developed at the same time that we have more and more bacteria that are resistant to current ones." The ability to rapidly identify a specific disease-causing strain and its resistance profile would not only save time and money; it also could potentially slow the global increase in antimicrobial resistance, Wong stresses.
The cell phone testing device uses a microphotometric system integrated with gas-permeable microwell arrays that can swiftly determine a pathogen's resistance profile while eliminating the need for bulky supporting equipment, Wong says. The system can test samples with initial concentrations from 101 to 106 cfu/mL, using urinary tract infection as a model system.
"As engineers working in electro-microfluidics, we wanted to not just create a cool device, but to actually solve an important problem. We chose UTI because it is the most common bacterial infection and so already there is a huge market to support the technological development," Wong says. However, that does not mean the new system will be readily adopted. "One of the challenges is that UTI is bad for patients, but they are unlikely to die from it. To justify any new technology or diagnostic for that kind of disorder, we need to make the cost very low," he explains. "The cell phone platform seems to answer that need. After the technology matures, we envision that the same platform we're developing now will be applicable to many other diseases, in both the developing and developed worlds."
Wong, like Glynn, points to collaboration as a key factor in moving their projects forward. "Our own experience shows us that we absolutely need people from multiple fields to work together on this," he says. "As engineers, we know the technology. We're collaborating with experts in the urology department at Stanford who treat people with urinary tract infection so we can know that it works in the clinic." It's also important to collaborate with industry scientists, Wong emphasizes. "The commercial perspective on cost and manufacturing capability is critical for making a product a reality."
Learn More in the 2014 JALA Special Issue
In addition to the contributions from Lillehoj, Glynn and Wong, the 2014 JALA special issue, New Developments in Global Health Technologies, features review articles and additional original reports on developing, validating and implementing innovative technologies for the diagnosis and treatment of high global burden diseases.
The special issue is part of the SLAS commitment to improving access to information for health professionals, scientists and policy makers around the world, according to SLAS President Daniel Sipes. SLAS participates in the Health InterNetwork Access to Research Initiative (HINARI) by providing free or low-cost access to JALA and JBS to more than 6,000 publicly funded non-profit institutions in over 100 countries and territories in the developing world. In addition, deeply discounted membership rates make it easier for life sciences R&D professionals in emerging economies to join SLAS and enjoy full access to its many programs, products, services and events.
SLAS also recently honored Patrick Beattie with the 2014 SLAS Innovation Award. Beattie is director of operations for Diagnostics for All, a non-profit committed to creating low-cost, easy-to-use point-of-care diagnostics for remote areas of the developing world.