Stem-cell scientists at McMaster University have developed a way to directly convert adult human blood cells to sensory neurons, providing the first objective measure of how patients may feel things like pain, temperature, and pressure, the researchers reveal in an open-access paper in the journal Cell Reports.

Currently, scientists and physicians have a limited understanding of the complex issue of pain and how to treat it. “The problem is that unlike blood, a skin sample or even a tissue biopsy, you can’t take a piece of a patient’s neural system,” said Mick Bhatia, director of the McMaster Stem Cell and Cancer Research Institute and research team leader. “It runs like complex wiring throughout the body and portions cannot be sampled for study.

“Now we can take easy to obtain blood samples, and make the main cell types of neurological systems in a dish that is specialized for each patient,” said Bhatia. “We can actually take a patient’s blood sample, as routinely performed in a doctor’s office, and with it we can produce one million sensory neurons, [which] make up the peripheral nerves. We can also make central nervous system cells.”

Testing pain drugs

The new technology has “broad and immediate applications,” said Bhatia: It allows researchers to understand disease and improve treatments by asking questions such as: Why is it that certain people feel pain versus numbness? Is this something genetic? Can the neuropathy that diabetic patients experience be mimicked in a dish?

It also paves the way for the discovery of new pain drugs that don’t just numb the perception of pain. Bhatia said non-specific opioids used for decades are still being used today. “If I was a patient and I was feeling pain or experiencing neuropathy, the prized pain drug for me would target the peripheral nervous system neurons, but do nothing to the central nervous system, thus avoiding addictive drug side effects,” said Bhatia.

“Until now, no one’s had the ability and required technology to actually test different drugs to find something that targets the peripheral nervous system, and not the central nervous system, in a patient-specific, or personalized manner.”

A patient time machine 

Bhatia’s team also successfully tested their process with cryopreserved (frozen) blood. Since blood samples are taken and frozen with many clinical trials, this give them “almost a bit of a time machine” to run tests on neurons created from blood samples of patients taken in past clinical trials, where responses and outcomes have already been recorded.

In the future, the process may have prognostic (predictive diagnostic) potential, explained Bhatia: one might be able to look at a patient with Type 2 Diabetes and predict whether they will experience neuropathy, by running tests in the lab using their own neural cells derived from their blood sample.

“This bench-to-bedside research is very exciting and will have a major impact on the management of neurological diseases, particularly neuropathic pain,” said Akbar Panju, medical director of the Michael G. DeGroote Institute for Pain Research and Care, a clinician and professor of medicine.

“This research will help us understand the response of cells to different drugs and different stimulation responses, and allow us to provide individualized or personalized medical therapy for patients suffering with neuropathic pain.”

This research was supported by the Canadian Institutes of Health Research, Ontario Institute of Regenerative Medicine, Marta and Owen Boris Foundation, J.P. Bickell Foundation, the Ontario Brain Institute, and Brain Canada.

Abstract of Single Transcription Factor Conversion of Human Blood Fate to NPCs with CNS and PNS Developmental Capacity

The clinical applicability of direct cell fate conversion depends on obtaining tissue from patients that is easy to harvest, store, and manipulate for reprogramming. Here, we generate induced neural progenitor cells (iNPCs) from neonatal and adult peripheral blood using single-factor OCT4 reprogramming. Unlike fibroblasts that share molecular hallmarks of neural crest, OCT4 reprogramming of blood was facilitated by SMAD+GSK-3 inhibition to overcome restrictions on neural fate conversion. Blood-derived (BD) iNPCs differentiate in vivo and respond to guided differentiation in vitro, producing glia (astrocytes and oligodendrocytes) and multiple neuronal subtypes, including dopaminergic (CNS related) and nociceptive neurons (peripheral nervous system [PNS]). Furthermore, nociceptive neurons phenocopy chemotherapy-induced neurotoxicity in a system suitable for high-throughput drug screening. Our findings provide an easily accessible approach for generating human NPCs that harbor extensive developmental potential, enabling the study of clinically relevant neural diseases directly from patient cohorts.

Stanford Bio-X scientists have created a robot that speeds and extends biomedical research with a common laboratory organism — fruit flies (Drosophila).

The robot can visually inspect awake flies and carry out behavioral experiments that were impossible with anesthetized flies. The work is described today (May 25) in the journal Nature Methods.

“Robotic technology offers a new prospect for automated experiments and enables fly researchers to do several things they couldn’t do previously,” said research team leader Mark Schnitzer, an associate professor of biology and of applied physics.

“For example, it can do studies with large numbers of flies inspected in very precise ways.” The group did one study of 1,000 flies in 10 hours, a task that would have taken much longer for even a highly skilled human.

Zap, you’re part of an experiment

When the robot’s fly-snatching apparatus is ready to grab a fly, it flashes a brief infrared blast of light that is invisible to the fly. The light reflects off its thorax, indicating the precise location of each fly and allowing the robot to recognize each individual fly by its reflection pattern. Then, a tiny, narrow suction tube strikes one of the illuminated thoraxes, painlessly sucking onto the fly and lifting it up.

Once the fly is attached, the robot uses machine vision to analyze the fly’s physical attributes, sort the flies by male and female, and even carry out a microdissection to reveal the fly’s minuscule brain. In one experiment, the robot’s machine vision was able to differentiate between two strains of flies so similar they are indistinguishable to the human eye.

Speeding disease research

All this is good news to the legion of graduate students who still spend hours a day looking at flies under a microscope as part of work that continues to uncover mechanisms in human aging, cancer, diabetes and a range of other diseases.

Although flies and humans have obvious differences, in many cases our cells and organs behave in similar ways and it is easier to study those processes in flies than in humans. The earliest information about how radiation causes gene mutations came from fruit flies, as did an understanding of our daily sleep/waking rhythms. And many of the molecules that are now famous for their roles in regulating how cells communicate were originally discovered by scientists hunched over microscopes staring at the unmoving bodies of anesthetized flies.

Now, that list of fruit fly contributions can be expended to include behavioral studies, previously impossible because the humans carrying out the analysis can neither see fly behaviors clearly nor distinguish between individuals.

In their paper, Schnitzer and his team had the robot pick up a fly and carry it to a trackball. Once there, they exposed the fly to different smells and could record how the fly behaved — racing along the trackball to get closer or attempting to turn away.

The work was funded by the W.M. Keck Foundation, the Stanford Bio-X program, an NIH Director’s Pioneer Award, and the Stanford-NIBIB Training Program in Biomedical Imaging Instrumentation.

Columbia Engineering researchers have created the first single-molecule diode — the ultimate in miniaturization for electronic devices — with potential for real-world applications in electronic systems.

The diode that has a high (>250) rectification and a high “on” current (~ 0.1 microamps), says Latha Venkataraman, associate professor of applied physics. “Constructing a device where the active elements are only a single molecule … which has been the ‘holy grail’ of molecular electronics, represents the ultimate in functional miniaturization that can be achieved for an electronic device,” he said.

With electronic devices becoming smaller every day, the field of molecular electronics has become ever more critical in solving the problem of further miniaturization, and single molecules represent the limit of miniaturization. The idea of creating a single-molecule diode was suggested by Arieh Aviram and Mark Ratner who theorized in 1974 that a molecule could act as a rectifier, a one-way conductor of electric current.

The future of miniaturization

Researchers have since been exploring the charge-transport properties of molecules. They have shown that single-molecules attached to metal electrodes (single-molecule junctions) can be made to act as a variety of circuit elements, including resistors, switches, transistors, and, indeed, diodes. They have learned that it is possible to see quantum mechanical effects, such as interference, manifest in the conductance properties of molecular junctions.

Since a diode acts as an electricity valve, its structure needs to be asymmetric so that electricity flowing in one direction experiences a different environment than electricity flowing in the other direction. To develop a single-molecule diode, researchers have simply designed molecules that have asymmetric structures.

“While such asymmetric molecules do indeed display some diode-like properties, they are not effective,” explains Brian Capozzi, a PhD student working with Venkataraman and lead author of the paper. “A well-designed diode should only allow current to flow in one direction …  and it should allow a lot of current to flow in that direction. Asymmetric molecular designs have typically suffered from very low current flow in both ‘on’ and ‘off’ directions, and the ratio of current flow in the two has typically been low. Ideally, the ratio of ‘on’ current to ‘off’ current, the rectification ratio, should be very high.”

To overcome the issues associated with asymmetric molecular design, Venkataraman and her colleagues — Chemistry Assistant Professor Luis Campos’ group at Columbia and Jeffrey Neaton’s group at the Molecular Foundry at UC Berkeley — focused on developing an asymmetry in the environment around the molecular junction. They created an environmental asymmetry through a rather simple method: they surrounded the active molecule with an ionic solution and used gold metal electrodes of different sizes to contact the molecule.

Avoiding quantum-mechanical effects

Their results achieved rectification ratios as high as 250 — 50 times higher than earlier designs. The “on” current flow in their devices can be more than 0.1 microamps, which, Venkataraman notes, is a lot of current to be passing through a single-molecule. And, because this new technique is so easily implemented, it can be applied to all nanoscale devices of all types, including those that are made with graphene electrodes.

“It’s amazing to be able to design a molecular circuit, using concepts from chemistry and physics, and have it do something functional,” Venkataraman says. “The length scale is so small that quantum mechanical effects are absolutely a crucial aspect of the device. So it is truly a triumph to be able to create something that you will never be able to physically see and that behaves as intended.”

She and her team are now working on understanding the fundamental physics behind their discovery, and trying to increase the rectification ratios they observed, using new molecular systems.

The study, described in a paper published today (May 25) in Nature Nanotechnology, was funded by the National Science Foundation, the Department of Energy, and the Packard Foundation.