Cells within our bodies divide and change over time, with thousands of chemical reactions occurring within each cell daily. This makes it difficult for scientists to understand whats happening inside. Now, tiny nanostraws developed by Stanford researchers offer a method of sampling cell contents without disrupting its natural processes.

Nicholas Melosh, associate professor of materials science and engineering, developed a new, non-destructive system for sampling cells with nanoscale straws. The system could help uncover mysteries about how cells function. (Image credit: L.A. Cicero)

A problem with the current method of cell sampling, called lysing, is that it ruptures the cell. Once the cell is destroyed, it cant be sampled from again. This new sampling system relies on tiny tubes 600 times smaller than a strand of hair that allow researchers to sample a single cell at a time. The nanostraws penetrate a cells outer membrane, without damaging it, and draw out proteins and genetic material from the cells salty interior.

Its like a blood draw for the cell, said Nicholas Melosh, an associate professor of materials science and engineering and senior author on a paper describing the work published recently in Proceedings of the National Academy of Sciences.

The nanostraw sampling technique, according to Melosh, will significantly impact our understanding of cell development and could lead to much safer and effective medical therapies because the technique allows for long term, non-destructive monitoring.

What we hope to do, using this technology, is to watch as these cells change over time and be able to infer how different environmental conditions and chemical cocktails influence their development to help optimize the therapy process, Melosh said.

If researchers can fully understand how a cell works, then they can develop treatments that will address those processes directly. For example, in the case of stem cells, researchers are uncovering ways of growing entire, patient-specific organs. The trick is, scientists dont really know how stem cells develop.

For stem cells, we know that they can turn into many other cell types, but we do not know the evolution how do they go from stem cells to, say, cardiac cells? There is always a mystery. This sampling technique will give us a clearer idea of how its done, said Yuhong Cao, a graduate student and first author on the paper.

The sampling technique could also inform cancer treatments and answer questions about why some cancer cells are resistant to chemotherapy while others are not.

With chemotherapy, there are always cells that are resistant, said Cao. If we can follow the intercellular mechanism of the surviving cells, we can know, genetically, its response to the drug.

The sampling platform on which the nanostraws are grown is tiny about the size of a gumball. Its called the Nanostraw Extraction (NEX) sampling system, and it was designed to mimic biology itself.

In our bodies, cells are connected by a system of gates through which they send each other nutrients and molecules, like rooms in a house connected by doorways. These intercellular gates, called gap junctions, are what inspired Melosh six years ago, when he was trying to determine a non-destructive way of delivering substances, like DNA or medicines, inside cells. The new NEX sampling system is the reverse, observing whats happening within rather than delivering something new.

Its a super exciting time for nanotechnology, Melosh said. Were really getting to a scale where what we can make controllably is the same size as biological systems.

Building the NEX sampling system took years to perfect. Not only did Melosh and his team need to ensure cell sampling with this method was possible, they needed to see that the samples were actually a reliable measure of the cell content, and that samples, when taken over time, remained consistent.

When the team compared their cell samples from the NEX with cell samples taken by breaking the cells open, they found that 90 percent of the samples were congruous. Meloshs team also found that when they sampled from a group of cells day after day, certain molecules that should be present at constant levels remained the same, indicating that their sampling accurately reflected the cells interior.

With help from collaborators Sergiu P. Pasca, assistant professor of psychiatry and behavioral sciences, and Joseph Wu, professor of radiology, Melosh and co-workers tested the NEX sampling method not only with generic cell lines, but also with human heart tissue and brain cells grown from stem cells. In each case, the nanostraw sampling reflected the same cellular contents as lysing the cells.

The goal of developing this technology, according to Melosh, was to make an impact in medical biology by providing a platform that any lab could build. Only a few labs across the globe, so far, are employing nanostraws in cellular research, but Melosh expects that number to grow dramatically.

We want as many people to use this technology as possible, he said. Were trying to help advance science and technology to benefit mankind.

Melosh is also a professor in the photon science directorate at SLAC National Accelerator Laboratory, a member of Stanford Bio-X, the Child Health Research Institute, the Stanford Neurosciences Institute, Stanford ChEM-H and the Precourt Institute for Energy. Wu is also the Simon H. Stertzer, MD, Professor; he is director of the Stanford Cardiovascular Institute and a member of Stanford Bio-X, the Child Health Research Institute, Stanford ChEM-H and the Stanford Cancer Institute. Pasca is also a member of Stanford Bio-X, the Child Health Research Institute, the Stanford Neurosciences Institute and Stanford ChEM-H.

The work was funded by the National Institute of Standards and Technology, the Knut and Alice Wallenberg Foundation, the National Institutes of Health, Stanford Bio-X, the Progenitor Cell Biology Consortium, the National Institute of Mental Health, an MQ Fellow award, the Donald E. and Delia B. Baxter Foundation and the Child Health Research Institute.

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Stanford-developed nanostraws sample a cell's contents without damage - Stanford University News

February 21, 2017 at 2:28 AM

How we think and fall in love are controlled by lightning-fast electrochemical signals across synapses, the dynamic spaces between nerve cells. Until now, nobody knew that cancer cells can repurpose tools of neuronal communication to fuel aggressive tumor growth and spread.

UT Southwestern Medical Center researchers report those findings in two recent studies, one in the Proceedings of the National Academy of Sciences (PNAS) and the second in Developmental Cell.

"Many properties of aggressive cancer growth are driven by altered cell signaling," said Dr. Sandra Schmid, senior author of both papers and Chair of Cell Biology at UT Southwestern. "We found that cancer cells are taking a page from the neuron's signaling playbook to maintain certain beneficial signals and to squelch signals that would harm the cancer cells."

The two studies find that dynamin1 (Dyn1) - a protein once thought to be present only in nerve cells of the brain and spinal cord - is also found in aggressive cancer cells. In nerve cells, or neurons, Dyn1 helps sustain neural transmission by causing rapid endocytosis - the uptake of signaling molecules and receptors into the cell - and their recycling back to the cell surface. These processes ensure that the neurons keep healthy supplies at the ready to refire in rapid succession and also help to amplify or suppress important nerve signals as necessary, Dr. Schmid explained.

"This role is what the cancer cells have figured out. Aggressive cancer cells have usurped the mechanisms that neurons use for the rapid uptake and recycling of neural transmitters. Instead of neural transmitters, the cancer cells use Dyn1 for rapid uptake and recycling of EGF (epidermal growth factor) receptors. Mutations in EGF receptors are drivers of breast and lung cancers," she said of the Developmental Cell study.

In order to thrive, cancer cells must multiply faster than nearby noncancerous cells. EGF receptors help them do that, she explained.

Cancer cell survival is another factor in disease progression. In the PNAS study, the Schmid lab found that aggressive cancer cells appear to have adapted neuronal mechanisms to thwart a key cancer-killing pathway triggered by activating "death receptors" (DRs) on cancer cells. Specifically, aggressive cancer cells appear to have adapted ways to selectively activate Dyn1 to suppress DR signaling that usually leads to cancer cell death.

"It is amazing that the aggressive cancers use a signaling pathway to increase the activity of EGF and also turn on Dyn1 pathways to suppress cancer death - so you have this vicious circle," said Dr. Schmid, who holds the Cecil H. Green Distinguished Chair in Cellular and Molecular Biology.

She stressed that less aggressive cancers respond to forms of chemotherapy that repress EGF signaling and/or die in response to the TRAIL-DR pathway. However, aggressive lung and breast cancer cells have adapted ways to commandeer the neuronal mechanisms identified in these studies.

The hope is that this research will someday lead to improved strategies to fight the most aggressive cancers, she said. Currently, her laboratory is conducting research to identify Dyn1 inhibitors as potential anticancer drugs using a 280,000-compound library in a shared facility at UT Southwestern.

"Cancer is a disease of cell biology. To grow, spread, and survive, cancer cells modify normal cellular behavior to their advantage. They can't reinvent the underlying mechanisms, but can adapt them. In these studies, we find that some cancer cells repurpose tools that neurons use in order to get a competitive advantage over nearby normal cells," she said.

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Cancer cells adapt nerve cell mechanisms to fuel aggressive tumor ... - News-Medical.net