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Disruptive Technologies Poised to Transform Drug Discovery

Innovators from Rice University, Promega Corporation, 908 Devices and the Genomics Institute of the Novartis Research Foundation are transforming researchers' efforts to identify new and effective treatments. Their disruptive technologies are streamlining drug discovery by making the process faster and more cost effective without sacrificing quality.

 

"I like Eric Topol's description of a disruptive innovation," says Daniel Sipes, M.S., director of Advanced Automation Technologies at the Genomics Institute of the Novartis Research Foundation (GNF) in San Diego, CA, and chair of the SLAS2014 Disruptive Technologies special session. "The invention of the automobile itself wasn't disruptive—but bringing it to the masses, as Henry Ford did, was. It is truly exciting to bring innovations into practice, enabling others to benefit from the work in the quest to discover new medicines."

Using an Open-Source 3D Printer to Create Vascular Structures

The world of 3D tissue culture has advanced "tremendously" over the past decade, as scientists strive to study cell behavior in environments that are closer to how cells live in the human body, rather than on plates of glass, says Jordan Miller, Ph.D., assistant professor of engineering and founder of the Advanced Manufacturing Research Program at Rice University in Houston, TX. Today, laboratories are engineering tissues that could eventually be used not only to test potential therapeutic compounds, but also as replacements for damaged organs. "There have been some successes in treating humans with materials made from their own cells. However, most of those successes have been in very thin tissues—skin, cornea and the urinary bladder. "When you have a thin layer of tissue, transplanted cells can get nutrients and oxygen just by diffusion; they don't need their own blood supply to survive and function," Miller explains.

It's a different story for more complex organs such as hearts and kidneys."Complex organs have dozens more cell types; the architectures are very complicated; and instead of needing zero blood vessel networks, you have have multiple blood vessel networks to deal with," Miller observes. "You've got to think about cell density, and about arteries, veins and capillaries. You also have to think about interconnecting systems. For the liver, for example, you have to think about the lymphatic system and the bile duct system. And in terms of transplantation, we don't know which of these we're going to have to do, in what order, and what architecture would be best."

The 3D printing world faces similar challenges with respect to printing organs, Miller noted. Recently, scientists created and implanted a 3D-printed trachea, which is saving the life of an infant with a genetic disorder that causes the bronchial tube to collapse. But the trachea also is made up of thin tissue with a very simple architecture. Before a 3D-printed complex organ can be used for transplantation, there needs to be a way to ensure blood flow throughout the organ, or the cells at its core will die.

Miller and his colleagues have taken an "embryonic" step in the direction of helping to ensure blood flow, which he will describe in detail in the special session. Using an open-source 3D printer, his team created lattices made of biodegradable carbohydrate glass in which they encapsulated live cells in synthetic gels. When the carbohydrate glass dissolved, they were left with perfusable, interconnected channels. "Right now, we're trying to make tissues that have enough cells at a high enough density that we can keep alive with this 'vasculature' for at least a couple of weeks so we can do some experiments," Miller says.

"What's exciting is that technologies such as 3D printing give use reproducibility we didn't have before. We can generate dozens of these gels in a single day, which empowers the statistical significance of our research," says Miller. "In addition, as we do our work, I've been struck consistently by the similarities in vascular perfusion among many different tissue types. So I think if we do create an effective vasculature for one type of cell, we can extend the method very easily to other cell types and other gel types."

Sipes observed that the ability to tap into open source hardware and software, as Miller did, and his group's willingness to share their designs online, "democratizes" efforts to create 3D models of disease, making such investigations accessible to labs that can't afford to spend hundreds of thousands of dollars on a 3D printer and related technologies.

Luciferase Sheds Light on Target Engagement in Living Cells

Keith Wood, Ph.D., head of Research and Advanced Technologies and senior research fellow at Promega Corporation, headquartered in Madison, WI, will discuss Promega's NanoLuc luciferase technology, which was named one of the The Scientist magazine's top 10 innovations of 2012, because it enables drug-discovery scientists to tell "not only if a particular compound works in cells or not, but also what the target is and how tightly it interacts with that target," he says. "In a sense, this technology has the potential to marry the analytical information that comes from biochemical/target-based screening with the biological system information that comes from live-cell screening."

Wood explains: "What we have developed is a new approach to intracellular energy transfer that allows researchers to not only see the binding of synthetic molecules to their intracellular targets [target engagement], but also to see the biological consequences of this binding within the same cells. If you can generate new drug leads in a more biologically relevant context, you should expect greater success as you move down the development chain to preclinical and, ultimately, clinical testing."

Until now, measuring target engagement within living cells has been "almost impossible," Wood says. The closest researchers had come before was looking at biological correlates of engagement. For example, if a researcher had a compound that inhibited a kinase, certain biological events—auto-phosphorylation of the kinase, for example—could occur very close to the binding event. "The researcher might then decide to use a measure of auto-phosphorylation as the measure of the engagement of the compound to the target." Other groups are using changes in protein degradation rates as "correlated observables" or "correlated parameters," Wood notes.

The new technology enables researchers to forego biological correlates and look directly at both a compound's binding using physical processes that are observable from within a cell. "We placed this new, very bright luciferase on a target, where it served as an energy donor. Then we took a compound known to bind to that target and attached a fluorophore to it. During the binding event, the fluorophore accepted the energy from the luciferase and re-emitted it as a different color," Wood explains. If a researcher then adds a potential drug lead to a cell and it binds to the target, he or she will see changes in the energy transfer and know the compound is binding by its ability to displace the fluorophore. "This means we're no longer looking for biological correlates; the energy transfer itself is a direct consequence of the binding event," Wood says. At that point, the researcher is in a position to "interrogate" the binding event—for example, by testing different compositions of the compound to see if they bind better or more productively to the target.

Wood will elaborate on the design and potential uses of the new luciferase in the special session. "Up to this point, we've mainly shown that it works and provides us with reliable information inside cells," he says. "Now we're poised to show how we can make meaningful discoveries with it."

Handheld Mass Spectrometers on the Near Horizon

Christopher Brown's effort to create a handheld mass spectrometer also will "democratize a technology that costs hundreds of thousands of dollars, and normally is done in core labs," says Sipes. "It has the potential to put mass specs in every general lab, thereby greatly accelerating assay development."

Brown, Ph.D., a co-founder, vice president and chief technology officer at 908 Devices in Boston, MA, has a history of working on miniaturizing laboratory technologies, particularly in the safety and security arena. At Ahura Scientific (now Thermo Scientific), he helped create the first handheld Raman spectrometer, capable of identifying more than 10,000 potentially hazardous materials on site. "It's extremely easy to use, even though the technology inside it is extraordinarily complex," Brown says. "We not only had to take it from 80 lbs. to 3 lbs; the system needed to do complete data interpretation behind the scenes to give the user immediate, reliable identification."

Brown joined others involved in miniaturized systems to form 908 Devices, where the team now is developing the handheld mass spectrometer. "People have been talking about and working on miniaturizing mass spec for several decades. But we haven't gotten beyond the 30-to-40 lb. territory, and the devices still need to be used by trained mass spectrometrists; they're not exactly smart phone quality in terms of usability," he says.

"The challenge with trying to make a mass spectrometer extremely small and robust is that normally they run under a crazy extreme vacuum— usually a millionth of an atmosphere or more — and you need some large, power-hungry pumps to get to that pressure," Brown explains. "In that scenario, even if you can make other parts of the device small, you're still stuck with 25 pounds of fragile pumps, and that was fundamentally limiting."

Enter J. Michael Ramsey, Ph.D., Goldby Distinguished Professor of Chemistry at the University of North Carolina-Chapel Hill, director of the UNC Center for Biomedical Microtechnologies at the University of North Carolina and a member of 908 Device's board of directors. Earlier, Ramsey took an innovative approach to the problem, by asking and subsequently investigating whether a mass spectrometer could be made to run at higher pressure. His research demonstrated operation at a thousand times the usual pressure—and that work forms the basis of the team's current efforts.

"Our first product is geared to the safety space," Brown says. "Currently, during an industrial accident or a spill, identifying hazardous compounds with a trace analysis requires putting on protective equipment, grabbing a sample, bottling it up and packaging it in a way that is safe for transportation, and taking it away from the incident for analysis. That can take many hours, and means an entire site is shut down until results come in and people understand what's going on. If we can get the mass spectrometer capability out of the lab and into the field, they could have actionable answers in seconds."

A 3-pound mass spectrometer has limitations, however. "We need to constrain the capabilities of the hardware in order to retain excellent sensitivity and selectivity for a particular class of problems," Brown says. "For each class of application—if we wanted to do get samples into the unit for a life science analysis, for example—we would need a different product. The enabling technology that lets the instrument run at high pressures is the same. But we'd need to hone the rest of the instrument to excel at that specific problem."

The security-focused handheld will be on the market in 2014, but meanwhile, "we have our ears to the ground and are talking with many different people," Brown observes.

Exploring the Mechanisms of Mechanotransduction

Sipes and Michael Bandell, Ph.D., a research investigator at GNF, are among the GNF researchers led by Ardem Patapoutian, who are investigating the somatosensory neurons that allow humans to sense touch and temperature, as well as other cells that are mechano-sensitive. These cells express specialized ion channels that are believed to influence not just the sense of touch, but various clinical conditions. Early in the research process, the team modified a commercial device called a FLIPR® (Molecular Devices, LLC), which generally is used to identify early leads against GPCR and ion channel targets, Sipes explains. That modification allowed the team to rapidly change temperature of the cells rather than add a chemical agonist or antagonist, and monitor cell activation.

The group then modified the device so that instead of activating cells with chemicals or temperature, they could use pressure (touch). "We imparted energy into the wells from the top and imaged the response of the cells from the bottom of the plate," Sipes says. Recently we discovered a new class of receptors, called the Piezo receptors, that respond to mechanical stimulation." Through a synergy of engineers working closely with clever biologists we aim to scale up such studies and discover novel mechanisms of mechanotransduction.

The clinical implications of the findings, which Bandell will address in the special session, are just beginning to emerge. "Mechanotransduction is likely to be relevant to more processes than we think," Bandell says. "For example, I find it fascinating that red blood cells express mechanosensitive ion channels—they're not the first cell type that comes to mind when I think of mechanotransduction. Yet Piezo 1 is present in red blood cells, and our recent paper shows that mutations in Piezo 1 affect these cells and cause a condition called dehydrated hereditary stomatocytosis." Endothelial cells that line blood vessels are also mechanically sensitive, and forces exerted on these cells could underlie conditions such as arteriosclerosis, he speculates. Disorders of mechanotransduction also have been implicated in the development of muscular dystrophies, cardiomyopathies and cancer.

Bandell is optimistic that the team's investigations of mechanotransduction could expand the scope of drug-discovery research. "I believe there's a growing appreciation in the research community of the need to look not only at the chemical environment of a cell, but also at how mechanical forces can affect the cell by activating certain signal pathways," he concludes.

Learn More at SLAS2014

Sipes will moderate the Disruptive Technologies special session at SLAS2014 featuring Miller, Wood, Brown and Bandell. It will be held Monday, January 20, from 10:30 a.m. - 12:30 p.m. at the San Diego Convention Center. It also will be available via live stream – check the SLAS2014 website close to the event for details.
 

December 16, 2013