Speak Friend and Enter: How Cells Let the Right Travelers through their Doors

For decades, it’s been a molecular mystery that scientists were seemingly unable to solve: how do large molecules pass through the cell and into the nucleus, while others half their size remain stranded outside?

These are nuclear pores imaged by atomic force microscopy, appearing as a craterlike landscape in which each crater corresponds to a pore of ~100 nm diameter. [Credit: UCL]

Nuclear pores imaged by atomic force microscopy, appearing as a crater-like landscape in which each crater corresponds to a pore of ~100 nm diameter. [Credit: UCL]

But as reported in the latest issue of Nature Nanotechnology, researchers now believe they may have cracked the case. By shedding light on this strange anomaly, University College London (UCL) scientists have opened the door for one day delivering gene therapies directly into the nucleus. With numerous research teams working on ways to merge stem cell therapy and gene therapy, this could be extremely valuable to our field.

Scientists already knew that the membrane that surrounds the cell’s nucleus is ‘punctured’ with millions of tiny holes, known as nuclear pores. Co-lead author Bart Hoogenboom likened the pores to a strange kind of sieve:

“The pores have been to known to act like a sieve that could hold back sugar while letting grains of rice fall through at the same time, but it was not clear how they were able to do that.”

In this study—which used cells taken from frog eggs—Hoogenboom, along with co-lead author Ariberto Fassati, harnessed atomic force microscopy (AFM) to give them a new understanding of how these pores work. Like a blind person moving their fingers to read braille, AFM uses a tiny needle to pass over the nuclear pores in order to measure their shape and structure.

“AFM can reveal far smaller structures than optical microscopes,” said Hoogenboom, “but it’s feeling more than seeing. The trick is to press hard enough to feel the shape and the hardness of the sample, but not so hard that you break it. [In this study], we used it to successfully probe the membrane…to reveal the structure of the pores.”

And what they found, adds Fassati, offered an explanation for how these pores worked:

“We found that the proteins in the center of the pores tangle together just tightly enough to form a barrier—like a clump of spaghetti. Large molecules can only pass through [the pores] when accompanied by chaperone molecules. These chaperones, called nuclear transport receptors, have the property of lubricating the [spaghetti] strands and relaxing the barrier, letting the larger molecules through.”

Astoundingly, Fassati said that this process happens upwards of several thousand times per second.

These results are exciting not only for solving a long-standing mystery, but also for pointing to new ways of delivering gene therapies.

As evidenced by recent clinical advances in conditions such as sickle cell disease and SCID (‘bubble baby’ disease), gene therapy represents a promising way to treat—and even cure—patients. Hoogenboom and Fassati are optimistic that their team’s discovery could lead further refinements to gene therapy techniques.

Said Fassati, “It may be possible to improve the design of current mechanisms for delivering gene therapy to better cross the nuclear pores and deliver their therapeutic genes into the nucleus.”

Spinal cord injury and stem cell research; find out the latest in a Google Hangout

Spinal cord injuries are devastating, leaving the person injured facing a life time of challenges, and placing a huge strain on their family and loved ones who help care for them.

The numbers affected are not small. More than a quarter of a million Americans are living with spinal cord injuries and there are more than 11,000 new cases each year.

It’s not just a devastating injury, it’s also an expensive one. According to the National Spinal Cord Injury Statistical Center it can cost more than $775,000 to care for a patient in the first year after injury, and the estimated lifetime costs due to spinal cord injury can be as high as $3 million.

Right now there is no cure, and treatment options are very limited. We have heard for several years now about stem cell research aimed at helping people with spinal cord injuries, but where is that research and how close are we to testing the most promising approaches in people?

That’s going to be the focus of a Google Hangout on Spinal Cord Injury and Stem Cell Research that we are hosting tomorrow, Tuesday, November 18 from noon till 1pm PST.

We’ll be looking at the latest stem cell-based treatments for spinal cord injury including work being done by Asterias Biotherapeutics, which was recently given approval by the Food and Drug Administration (FDA) to start a clinical trial for spinal cord injury. We are giving Asterias $14.3 million to carry out that trial and you can read more about that work here.

We’re fortunate in having three great guests for the Hangout: Jane Lebkowski, Ph.D., the President of research and development at Asterias; Roman Reed, a patient advocate and tireless champion of stem cell research and the founder of the Roman Reed Foundation; and Kevin Whittlesey, Ph.D., a CIRM science officer, who will discuss other CIRM-funded research that aims to better understand spinal cord injury and to bring stem cell-based therapies to clinic trials.

You can find out how to join the Hangout by clicking on the event page link: http://bit.ly/1sh1Dsm

The event is free and interactive, so you’ll be able to ask questions of our experts. You don’t need a Google+ account to watch the Hangout – just visit the event page at the specified time. If you do have a G+ account, please RSVP at the event page (link shown above). Also, with the G+ account you can ask questions in the comment box on this event page. Otherwise, you can tweet questions using #AskCIRMSCI or email us at info@cirm.ca.gov.

We look forward to seeing you there!

Entrepreneurship and Education

Guest author Neil Littman is CIRM’s Business Development Officer.

CIRM works closely with UCSF on a number of initiatives, from providing funding to academic investigators to jointly hosting events such as the recent CIRM Showcase with J-Labs held at the Mission Bay campus.

Beyond our joint initiatives, UCSF also provides many other valuable resources and educational opportunities to the life sciences community in the Bay Area. For instance, I was a mentor in UCSF’s “Idea to IPO” class which focused on helping students translate concepts into a commercializable product and viable business.

Another opportunity that may be of interest to all you budding entrepreneurs is UCSF’s Lean LaunchPad course, which kicks off in January (application deadline is Nov 19th). The course teaches…

“scientists and clinicians how to assess whether the idea or technology they have can serve as the basis of a business. The focus is on the marketplace where you must validate that your idea has value in order to move into the commercial world.”

See more at: Lean Launchpad for Life Sciences & Healthcare.

The course is being run out of the Entrepreneurship Center at UCSF, which is a division of the UCSF Office of Innovation, Technology & Alliances (ITA).

Ideas and Energy Reveal Surprises at Stem Cell Showcase

Janssen, the company within the pharmaceutical giant Johnson & Johnson responsible for much of its research and development, has a branch in the Bay Area called J Labs. It seeks to foster innovation in all sectors of biomedical research. One piece of that effort brings together innovators for monthly gatherings to exchange ideas and network. The events have an upbeat sense of energy so it was exciting when they invited CIRM to put together an all-day session dubbed: CIRM Showcase: Accelerating Stem Cell Treatments to Patients.

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The resulting showcase yesterday had that energy. But for someone who knows the CIRM portfolio of projects backward and forward, I thought, there were a few pleasant surprises. Perhaps the most exciting news came from Linda Marban, CEO of Capricor, the company CIRM is funding to complete a clinical trial in patients with weakened hearts after a heart attack. She disclosed that the company’s next target is the heart remodeling that is the cause of death in most boys with Duchenne muscular dystrophy. She said some early data would be released at the American Heart Association meeting in Chicago in two weeks.

Another bit of news—most exciting for science wonks—came from the biotech company Sangamo that CIRM funds to develop genetically modified blood stem cells as therapy for two diseases, HIV and beta thalassemia. The firm has developed a molecular scissors called a zinc finger nuclease that can splice the DNA that makes our genes. I knew the technique was pretty precise, but Curt Herberts from the company said they had perfected it to where it could get down to a single base pair—a single link in the chain that makes up our DNA. This greatly reduces the chances for any unintended effects of the genetic manipulation.

Two advances I learned about were in using iPS type stem cells as models for disease and for discovery of traditional drugs to treat those diseases. Ashkan Javaherian, from Steve Finkbeiner’s lab at the Gladstone Institutes, described some results with the robotic microscope they have developed that lets them screen hundreds of molecules on neurons grown from iPS cells reprogrammed from patients with specific diseases. Looking just at compounds already approved by the Food and Drug Administration (FDA), ones that could be put in the clinic quickly, they found four that reduced the degradation normally seen in neurons grown from patients with Huntington’s disease.

Similarly, Joseph Wu of Stanford described his work with cells from families with various genetic heart disorders. In addition to getting individualized information from the patient-specific cells, he said they could now take it one step further and sequence the entire DNA of the cells for just $500, yielding the chance to find out exactly what mutations were causing the disease. He said it was a big step towards truly personalized medicine and to developing therapies for various racial groups that respond differently to drugs.

The day began with our President and CEO C. Randall Mills detailing his plans for a nimbler, more responsive CIRM he has dubbed CIRM 2.0. This crowd seemed thrilled with his plan for an open call for applications so that they could come in with a request when they are ready instead of forcing them into a premature application for funding because the window might not open for another year or two.

One bit of trivia drove home how difficult the entire process of moving innovative therapies into the clinic can be. Paul Laikind, CEO of ViaCyte, the company CIRM has provided more than $50 million to develop a diabetes therapy, noted the size of the application they sent to the FDA: 8,500 pages. Kind of says it all.

Don Gibbons

Scientists Develop Stem Cell ‘Special Forces’ in order to Target, Destroy Brain Tumors

Curing someone of cancer is, in theory, a piece of cake: all you have to do is kill the cancer cells while leaving the healthy cells intact.

But in practice, this solution is far more difficult. In fact, it remains one of the great unsolved problems in modern oncology: how do you find, target and destroy each individual cancer cell in the body—while minimizing damage to the surrounding cells.

Encapsulated toxin-producing stem cells (in blue) help kill brain tumor cells in the tumor resection cavity (in green). [Credit: Khalid Shah, MS, PhD]

Encapsulated toxin-producing stem cells (in blue) help kill brain tumor cells in the tumor resection cavity (in green). [Credit: Khalid Shah, MS, PhD]

But luckily, Harvard Stem Cell Institute scientists at Massachusetts General Hospital may have finally struck gold: they have designed special, toxin-secreting stem cells that can target and destroy brain tumors. Their findings, which were performed in laboratory mice and which appear in the latest issue of the journal STEM CELLS, offer up an entirely unique method for eradicating deadly cancers.

Harvard Neuroscientist Khalid Shah, who led the study, explained in last Friday’s news release that the idea of engineering stem cells to kill cancer cells is not new—but there was a key difference in scientists’ ability to target individual cells vs. difficult-to-reach tumors, which is often the case with brain cancer:

“Cancer-killing toxins have been used with great success in a variety of blood cancers, but they don’t work as well in solid tumors because the cancers aren’t as accessible and the toxins have a short half-life.”

The solution, Shah and his team argued, was stem cells. Previously, Shah and his team discovered that stem cells could be used to circumvent these problems. The fact that stem cells continuously renew meant that they could also be used to continually deliver toxins to brain tumors.

“But first, we needed to genetically engineer stem cells that could resist being killed themselves by the toxins,” said Shah.

In this study, the research team introduced a small genetic change, or mutation, into the stem cells so that they become impervious to the toxin’s harmful effects. They then introduced a second mutation that allowed the stem cells to maintain and produce and secrete toxins throughout the cells’ lifetime—effectively giving it an unlimited supply of ammunition to use once it encountered the brain tumor.

They then employed a common technique whereby the toxins were tagged so that they only sought out and infected cancer cells—leaving healthy cells unscathed.

“We tested these stem cells in a clinically relevant mouse model of brain cancer,” Shah described. “After doing all of the molecular analysis and imaging to track the inhibition of protein synthesis within brain tumors, we do see the toxins kill the cancer cells and eventually prolonging the survival in animal models.”

While preliminary, these results are encouraging. As the team continues to refine their method of development and delivery, they are optimistic that they can bring their methods to clinical trial within the next five years.

These Are the Cells You’re Looking for: Scientists Devise New Way to Extract Bone-Making Stem Cells from Fat

Buried within our fat tissue are stashes of stem cells—a hidden reservoir of cells that, if given the right cues, can transform into cells that make up bone, cartilage or fat. These cells therefore represent a much-needed store for regenerative therapies that rebuild bone or cartilage lost to disease or injury.

Finding cells that have bone-making potential is more efficiently done by looking at the genes they express (in this case, ALPL) than at proteins on their surface. The bone matrix being produced by cells is stained red in samples of cells that do not express ALPL (left), those that do express ALPL (right). [Credit: Darling lab/Brown University]

Finding cells that have bone-making potential is more efficiently done by looking at the genes they express (in this case, ALPL) than at proteins on their surface. The bone matrix being produced by cells is stained red in samples of cells that do not express ALPL (left), those that do express ALPL (right). The center image shows both types of cells prior to sorting [Credit: Darling lab/Brown University]

The only problem with these tucked-away cellular reservoirs, however, is identifying them and getting them out.

But now, researchers at Brown University have devised a unique method of identifying, extracting and then cultivating these bone-producing stem cells. Their results, published today in the journal Stem Cell Research & Therapy, seem to offer a much-needed alternative resource for growing bone.

Traditional methods attempting to locate and extract these stem cells focused on proteins that reside on the surface of the cells. Find the proteins, scientists reasoned, and you’ve found the cell.

Unfortunately, that method was not fool proof, and many argued that it wasn’t finding all the cells that reside in the fat tissue. So Brown scientists, led by Dr. Eric Darling found an alternative.

They knew that a gene called ALPL is an indicator of bone-making cells. If the gene is switched on, the cell has the potential to make bone. If it’s switched off, it does not. So Darling and his team devised a fluorescent marker, or tag, that stuck to the cells with activated ALPL. They then used a special machine to sort the cells: those that glowed went into one bucket, those that did not went into the other.

To prove that these ALPL-activated cells were indeed capable of becoming bone and cartilage, they then cultivated them for several weeks in a petri dish. Not only did they transform into the right cell types—they did so in greater numbers than cells extracted using traditional methods.

Hetal Marble, a graduate student in Darling’s lab and the paper’s first author, argues that tagging genes—rather than surface proteins—in order to distinguish and weed out cell types represents an important paradigm shift in the field. As he stated in a press release:

“Approaches like this allow us to isolate all the cells that are capable of doing what we want, whether they fit the archetype of what a stem cell is or is not. The paradigm shift is thinking about isolating populations that are able to achieve an end point rather than isolating populations that fit a strictly defined archetype.”

While their method is both precise and accurate, there is one drawback: it is slow.

Currently, it takes four days to tag, extract and cultivate the bone-making cells. In the future, the team hopes they can shorten this time frame so that they could perform the required steps within a single surgical session. As Darling stated:

“If you can take a patient into the OR, isolate a bunch of their cells, sort them and put them back in—that’s ideally where we’d like to go with this.”

See You Next Week: 2014 Stem Cell Meeting on the Mesa

Next week marks the fourth annual Stem Cell Meeting on the Mesa (SCMOM) Partnering Forum in La Jolla, California and CIRM , one of the main organizers, hopes to see you there.

SCMOM

SCMOM is the first and only meeting organized specifically for the regenerative medicine and cell therapy sectors. The meeting’s unique Partnering Forum brings together a network of companies—including large pharma, investors, research institutes, government agencies and philanthropies seeking opportunities to expand key relationships in the field. The meeting will feature presentations by 50 leading companies in the fields of cell therapy, gene therapy and tissue engineering.

Co-founded by CIRM and the Alliance for Regenerative Medicine (ARM), SCMOM has since grown both in participants and in quality. As Geoff MacKay, President and CEO of Organogenesis, Inc. and ARM’s Chairman, stated in a recent news release:

“This year the Partnering Forum has expanded to include an emphasis not only on cell therapies, but also gene and gene-modified cell therapy technologies. This, like the recent formation of ARM’s Gene Therapy Section, is a natural progression for the meeting as the advanced therapies sector expands.”

This year CIRM President and CEO Dr. C. Randal Mills, as well as Senior Vice President, Research & Development Dr. Ellen Feigal will be speaking to attendees. In addition, 12 CIRM grantees will be among the distinguished speakers, including Drs. Jill Helms, Don Kohn and Clive Svendsen, as well as leaders from Capricor, Asterias, ViaCyte, Sangamo Biosciences and others.

CIRM has made tremendous progress advancing stem cell therapies to patients and expects to have ten approved clinical trials by the end of 2014. The trials which span a variety of therapeutic areas using several therapeutic strategies such as cell therapy, monoclonal antibodies and small molecules are increasingly being partnered with major industry players. CIRM still has more than $1 billion to invest and is interested in co-funding with industry and investors—don’t miss the chance to strike the next partnership at SCMOM next week.

For more details and to view the agenda, please visit: http://stemcellmeetingonthemesa.com/

New Cellular Tracking Device Tests Ability of Cell-Based Therapies to Reach Intended Destination

Therapies aimed at replacing damaged cells with a fresh, healthy batch hold immense promise—but there remains one major sticking point: once you have injected new, healthy cells into the patient, how do you track them and how do you ensure they do the job for which they were designed?

New tracking technique could improve researchers' ability to test potential cell therapies.

New tracking technique could improve researchers’ ability to test potential cell therapies.

Unfortunately, there’s no easy solution. The problem of tracking the movement of cells during cell therapy is that it’s hard to stay on their trail they enter the body. They can get mixed up with other, native cells, and in order to test whether the therapy is working, doctors often have to rely on taking tissue samples.

But now, scientists at the University of California, San Diego School of Medicine and the University of Pittsburgh have devised an ingenious way to keep tabs on where cells go post injection. Their findings, reported last week in the journal Magnetic Resonance in Medicine, stand to help researchers identify whether cells are arriving at the correct destination.

The research team, lead by UCSD Radiology Professor Dr. Eric Ahrens, developed something called a periflourocarbon (PFC) tracer in conjunction with MRI technology. Testing this new technology in patients receiving immune cell therapy for colorectal cancer, the team found that they were better able to track the movement of the cells than with traditional methods.

“This is the first human PFC cell tracking agent, which is a new way to do MRI cell tracking,” said Ahrens in a news release. “It’s the first example of a clinical MRI agent designed specifically for cell tracking.”

They tagged these cells with atoms of fluorine, a compound that normally occurs at extremely low levels. After tagging the immune cells, the researchers could then see where they went after being injected. Importantly, the team found that more than one-half of the implanted cells left the injection site and headed towards the colon. This finding marks the first time this process had been so readily visible.

Ahrens explained the technology’s potential implications:

“The imaging agent technology has been shown to be able to tag any cell type that is of interest. It is a platform imaging technology for a wide range of diseases and applications.”

A non-invasive cell tracking solution could serve as not only as an attractive alternative to the current method of tissue sampling, it could even help fast-track through regulatory hurdles new stem cell-based therapies. According to Ahrens:

“For example, new stem cell therapies can be slow to obtain regulatory approvals in part because it is difficult, if not impossible, with current approaches to verify survival and location of transplanted cells…. Tools that allow the investigator to gain a ‘richer’ data set from individual patients mean it may be possible to reduce patient numbers enrolled in a trial, thus reducing total trial cost.”

What are the ways scientists see stem cells in the body? Check out our Spotlight Video on Magnetic Particle Imaging.

CIRM at Business of Personalized Medicine Summit

Exciting new technologies such as regenerative medicine, tissue engineering and gene therapy are already at the forefront of a new era of medicine. And today, CIRM’s own Business Development Officer, Neil Littman, moderated a panel titled The Impact of Next Generation Personalized Medicine Technologies: How Disruptive Tech Continues to Advance the Industry, at the annual Business of Personalized Medicine Summit.

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The panel discussed the innovative technologies we have at our disposal today, and provided a glimpse into the future—highlighting promising therapies already in the clinic as well as technologies that may be available in 5 to 10 years. For example, Curt Herberts, Senior Director of Corporate Development & Strategy from Sangamo BioSciences, discussed Sangamo’s grant under CIRM’s Strategic Partnership II Award, which uses genome-editing technology for a one-time treatment for the blood disorder Beta-thalassemia.

Importantly, the panel delved into potential paradigm shifts in medical care that may arise as a result of these new technologies, and discussed how to translate these cutting-edge technologies into human clinical trials. Carlos Olguin, Head of Bio/nano/Programmable Matter Group, Autodesk and Dr. Kumar Sharma, who directs the Center for Renal Translational Medicine University of California, San Diego La Jolla, rounded out the panel.

Finally, Neil asked panel members to discuss the issues surrounding market adoption and the potential resistance to paradigm-shifting technologies, the final hurdle in the delivery of much-needed therapies to patients.

Throwback Thursday: Scientists Create Synthetic Version of Earth’s Earliest Primordial Cells

Cells as we know them today—no matter the species—are feats of evolution; molecular machines with thousands of interlocking parts. But they didn’t start out that way.

Scientists have built a simplified cell membrane that mimics natural cellular processes and movements.

Scientists have built a simplified cell membrane that mimics natural cellular processes and movements.

Using the latest tools from the new field of synthetic biology, a team of biophysicists from Tecnische Universitaet Muenchen (TUM) in Munich, Germany, has constructed a synthetic version of an early cell, complete with some biomechanical function.

To build a primordial cell, the recipe is simple: all you need is a membrane shell, a couple of biomolecules that perform the most basic of functions, and some fuel to keep it going.

Here, TUM researchers used lipids (fat molecules) to create a double-layer cellular membrane that mimics a cell’s natural membrane. They then filled the membrane with microtubules, which acted as cellular ‘scaffolding’ to hold everything in place, and another molecule called ‘kinesin.’ These kinesin molecules serve as molecular ‘motors,’ transporting components throughout the cell by traveling along the microtubule scaffolding. Finally, they added the fuel: a compound called adenosine triphosphate, or ATP. The scientists likened this set-up to a liquid crystal layer within the membrane that is in a permanent state of motion. As lead author Felix Keber explained in a news release:

“One can picture the liquid crystal layer as tree logs drifting on the surface of a lake. When it becomes too congested, they line up in parallel but can still drift alongside each other.”

Once constructed, the research team then wanted to understand how these synthetic cells behaved, and if it would mimic natural cellular movements. And much to the team’s surprise—they did.

During a process called osmosis—where water droplets selectively pass through the membrane—the researchers noticed a change in the cells’ shape as water left the interior of the cell. The resulting membrane slack was causing the microtubules to stick out like spikes. These ‘spiked extensions’ were eerily similar to what the extensions that scientists have seen cells normally use to get around.

This observation cleared up a long-standing mystery: the way cells change shape and move around wasn’t random. The cells were simply following the basic laws of physics. This discovery then led the team to uncover the underlying mechanisms of other cellular behaviors—and even make predictions on other systems.

As the study’s lead author, Professor Andreas Bausch, stated in the same release:

“With our synthetic biomolecular model we have created a novel option for developing minimal cell models. It is ideally suited to increasing the complexity in a modular fashion in order to reconstruct cellular processes like cell migration or cell division in a controlled manner.”

In the future, the team hopes to build this knowledge to a point where they can understand the physical basis for deformed cells—with potential applications to disease modeling. Bausch added:

“That the artificially created system can be comprehensively described from a physical perspective gives us hope that in the next steps we will also be able to uncover the basic principles behind the manifold cell deformations.”