Tag Archives: organoids

Xenotransplantation—organs for transplantation in human patients—it’s a business and a science

The last time (June 18, 2018 post) I mentioned xenotransplantation (transplanting organs from one species into another species; see more here), it was in the context of an art/sci (or sciart) event coming to Vancouver (Canada).,

Patricia Piccinini’s Curious Imaginings Courtesy: Vancouver Biennale [downloaded from http://dailyhive.com/vancouver/vancouver-biennale-unsual-public-art-2018/]

The latest edition of the Vancouver Biennale was featured in a June 6, 2018 news item on the Daily Hive (Vancouver),

Melbourne artist Patricia Piccinini’s Curious Imaginings is expected to be one of the most talked about installations of the exhibit. Her style of “oddly captivating, somewhat grotesque, human-animal hybrid creature” is meant to be shocking and thought-provoking.

Piccinini’s interactive [emphasis mine] experience will “challenge us to explore the social impacts of emerging biotechnology and our ethical limits in an age where genetic engineering and digital technologies are already pushing the boundaries of humanity.”

Piccinini’s work will be displayed in the 105-year-old Patricia Hotel in Vancouver’s Strathcona neighbourhood. The 90-day ticketed exhibition [emphasis mine] is scheduled to open this September [2018].

(The show opens on Sept. 14, 2018.)

At the time, I had yet to stumble across Ingfei Chen’s thoughtful dive into the topic in her May 9, 2018 article for Slate.com,

In the United States, the clock is ticking for more than 114,700 adults and children waiting for a donated kidney or other lifesaving organ, and each day, nearly 20 of them die. Researchers are devising a new way to grow human organs inside other animals, but the method raises potentially thorny ethical issues. Other conceivable futuristic techniques sound like dystopian science fiction. As we envision an era of regenerative medicine decades from now, how far is society willing to go to solve the organ shortage crisis?

I found myself pondering this question after a discussion about the promises of stem cell technologies veered from the intriguing into the bizarre. I was interviewing bioengineer Zev Gartner, co-director and research coordinator of the Center for Cellular Construction at the University of California, San Francisco, about so-called organoids, tiny clumps of organlike tissue that can self-assemble from human stem cells in a Petri dish. These tissue bits are lending new insights into how our organs form and diseases take root. Some researchers even hope they can nurture organoids into full-size human kidneys, pancreases, and other organs for transplantation.

Certain organoid experiments have recently set off alarm bells, but when I asked Gartner about it, his radar for moral concerns was focused elsewhere. For him, the “really, really thought-provoking” scenarios involve other emerging stem cell–based techniques for engineering replacement organs for people, he told me. “Like blastocyst complementation,” he said.

Never heard of it? Neither had I. Turns out it’s a powerful new genetic engineering trick that researchers hope to use for growing human organs inside pigs or sheep—organs that could be genetically personalized for transplant patients, in theory avoiding immune-system rejection problems. The science still has many years to go, but if it pans out, it could be one solution to the organ shortage crisis. However, the prospect of creating hybrid animals with human parts and killing them to harvest organs has already raised a slew of ethical questions. In 2015, the National Institutes of Health placed a moratorium on federal funding of this nascent research area while it evaluated and discussed the issues.

As Gartner sees it, the debate over blastocyst complementation research—work that he finds promising—is just one of many conversations that society needs to have about the ethical and social costs and benefits of future technologies for making lifesaving transplant organs. “There’s all these weird ways that we could go about doing this,” he said, with a spectrum of imaginable approaches that includes organoids, interspecies organ farming, and building organs from scratch using 3D bioprinters. But even if it turns out we can produce human organs in these novel ways, the bigger issue, in each technological instance, may be whether we should.

Gartner crystallized things with a downright creepy example: “We know that the best bioreactor for tissues and organs for humans are human beings,” he said. Hypothetically, “the best way to get you a new heart would be to clone you, grow up a copy of yourself, and take the heart out.” [emphasis mine] Scientists could probably produce a cloned person with the technologies we already have, if money and ethics were of no concern. “But we don’t want to go there, right?” he added in the next breath. “The ethics involved in doing it are not compatible with who we want to be as a society.”

This sounds like Gartner may have been reading some science fiction, specifically, Lois McMaster Bujold and her Barrayar series where she often explored the ethics and possibilities of bioengineering. At this point, some of her work seems eerily prescient.

As for Chen’s article, I strongly encourage you to read it in its entirety if you have the time.

Medicine, healing, and big money

At about the same time, there was a May 31, 2018 news item on phys.org offering a perspective from some of the leaders in the science and the business (Note: Links have been removed),

Over the past few years, researchers led by George Church have made important strides toward engineering the genomes of pigs to make their cells compatible with the human body. So many think that it’s possible that, with the help of CRISPR technology, a healthy heart for a patient in desperate need might one day come from a pig.

“It’s relatively feasible to change one gene in a pig, but to change many dozens—which is quite clear is the minimum here—benefits from CRISPR,” an acronym for clustered regularly interspaced short palindromic repeats, said Church, the Robert Winthrop Professor of Genetics at Harvard Medical School (HMS) and a core faculty member of Harvard’s Wyss Institute for Biologically Inspired Engineering. Xenotransplantation is “one of few” big challenges (along with gene drives and de-extinction, he said) “that really requires the ‘oomph’ of CRISPR.”

To facilitate the development of safe and effective cells, tissues, and organs for future medical transplantation into human patients, Harvard’s Office of Technology Development has granted a technology license to the Cambridge biotech startup eGenesis.

Co-founded by Church and former HMS doctoral student Luhan Yang in 2015, eGenesis announced last year that it had raised $38 million to advance its research and development work. At least eight former members of the Church lab—interns, doctoral students, postdocs, and visiting researchers—have continued their scientific careers as employees there.

“The Church Lab is well known for its relentless pursuit of scientific achievements so ambitious they seem improbable—and, indeed, [for] its track record of success,” said Isaac Kohlberg, Harvard’s chief technology development officer and senior associate provost. “George deserves recognition too for his ability to inspire passion and cultivate a strong entrepreneurial drive among his talented research team.”

The license from Harvard OTD covers a powerful set of genome-engineering technologies developed at HMS and the Wyss Institute, including access to foundational intellectual property relating to the Church Lab’s 2012 breakthrough use of CRISPR, led by Yang and Prashant Mali, to edit the genome of human cells. Subsequent innovations that enabled efficient and accurate editing of numerous genes simultaneously are also included. The license is exclusive to eGenesis but limited to the field of xenotransplantation.

A May 30, 2018 Harvard University news release by Caroline Petty, which originated the news item, explores some of the issues associated with incubating humans organs in other species,

The prospect of using living, nonhuman organs, and concerns over the infectiousness of pathogens either present in the tissues or possibly formed in combination with human genetic material, have prompted the Food and Drug Administration to issue detailed guidance on xenotransplantation research and development since the mid-1990s. In pigs, a primary concern has been that porcine endogenous retroviruses (PERVs), strands of potentially pathogenic DNA in the animals’ genomes, might infect human patients and eventually cause disease. [emphases mine]

That’s where the Church lab’s CRISPR expertise has enabled significant advances. In 2015, the lab published important results in the journal Science, successfully demonstrating the use of genome engineering to eliminate all 62 PERVs in porcine cells. Science later called it “the most widespread CRISPR editing feat to date.”

In 2017, with collaborators at Harvard, other universities, and eGenesis, Church and Yang went further. Publishing again in Science, they first confirmed earlier researchers’ fears: Porcine cells can, in fact, transmit PERVs into human cells, and those human cells can pass them on to other, unexposed human cells. (It is still unknown under what circumstances those PERVs might cause disease.) In the same paper, they corrected the problem, announcing the embryogenesis and birth of 37 PERV-free pigs. [Note: My July 17, 2018 post features research which suggests CRISPR-Cas9 gene editing may cause greater genetic damage than had been thought.]

“Taken together, those innovations were stunning,” said Vivian Berlin, director of business development in OTD, who manages the commercialization strategy for much of Harvard’s intellectual property in the life sciences. “That was the foundation they needed, to convince both the scientific community and the investment community that xenotransplantation might become a reality.”

“After hundreds of tests, this was a critical milestone for eGenesis — and the entire field — and represented a key step toward safe organ transplantation from pigs,” said Julie Sunderland, interim CEO of eGenesis. “Building on this study, we hope to continue to advance the science and potential of making xenotransplantation a safe and routine medical procedure.”

Genetic engineering may undercut human diseases, but also could help restore extinct species, researcher says. [Shades of the Jurassic Park movies!]

It’s not, however, the end of the story: An immunological challenge remains, which eGenesis will need to address. The potential for a patient’s body to outright reject transplanted tissue has stymied many previous attempts at xenotransplantation. Church said numerous genetic changes must be achieved to make porcine organs fully compatible with human patients. Among these are edits to several immune functions, coagulation functions, complements, and sugars, as well as the PERVs.

“Trying the straight transplant failed almost immediately, within hours, because there’s a huge mismatch in the carbohydrates on the surface of the cells, in particular alpha-1-3-galactose, and so that was a showstopper,” Church explained. “When you delete that gene, which you can do with conventional methods, you still get pretty fast rejection, because there are a lot of other aspects that are incompatible. You have to take care of each of them, and not all of them are just about removing things — some of them you have to humanize. There’s a great deal of subtlety involved so that you get normal pig embryogenesis but not rejection.

“Putting it all together into one package is challenging,” he concluded.

In short, it’s the next big challenge for CRISPR.

Not unexpectedly, there is no mention of the CRISPR patent fight between Harvard/MIT’s (Massachusetts Institute of Technology) Broad Institute and the University of California at Berkeley (UC Berkeley). My March 15, 2017 posting featured an outcome where the Broad Institute won the first round of the fight. As I recall, it was a decision based on the principles associated with King Solomon, i.e., the US Patent Office, divided the baby and UCBerkeley got the less important part of the baby. As you might expect the decision has been appealed. In an April 30, 2018 piece, Scientific American reprinted an article about the latest round in the fight written by Sharon Begley for STAT (Note: Links have been removed),

All You Need to Know for Round 2 of the CRISPR Patent Fight

It’s baaaaack, that reputation-shredding, stock-moving fight to the death over key CRISPR patents. On Monday morning in Washington, D.C., the U.S. Court of Appeals for the Federal Circuit will hear oral arguments in University of California v. Broad Institute. Questions?

How did we get here? The patent office ruled in February 2017 that the Broad’s 2014 CRISPR patent on using CRISPR-Cas9 to edit genomes, based on discoveries by Feng Zhang, did not “interfere” with a patent application by UC based on the work of UC Berkeley’s Jennifer Doudna. In plain English, that meant the Broad’s patent, on using CRISPR-Cas9 to edit genomes in eukaryotic cells (all animals and plants, but not bacteria), was different from UC’s, which described Doudna’s experiments using CRISPR-Cas9 to edit DNA in a test tube—and it was therefore valid. The Patent Trial and Appeal Board concluded that when Zhang got CRISPR-Cas9 to work in human and mouse cells in 2012, it was not an obvious extension of Doudna’s earlier research, and that he had no “reasonable expectation of success.” UC appealed, and here we are.

For anyone who may not realize what the stakes are for these institutions, Linda Williams in a March 16, 1999 article for the LA Times had this to say about universities, patents, and money,

The University of Florida made about $2 million last year in royalties on a patent for Gatorade Thirst Quencher, a sports drink that generates some $500 million to $600 million a year in revenue for Quaker Oats Co.

The payments place the university among the top five in the nation in income from patent royalties.

Oh, but if some people on the Gainesville, Fla., campus could just turn back the clock. “If we had done Gatorade right, we would be getting $5 or $6 million (a year),” laments Donald Price, director of the university’s office of corporate programs. “It is a classic example of how not to handle a patent idea,” he added.

Gatorade was developed in 1965 when many universities were ill equipped to judge the commercial potential of ideas emerging from their research labs. Officials blew the university’s chance to control the Gatorade royalties when they declined to develop a professor’s idea.

The Gatorade story does not stop there and, even though it’s almost 20 years old, this article stands the test of time. I strongly encourage you to read it if the business end of patents and academia interest you or if you would like to develop more insight into the Broad Institute/UC Berkeley situation.

Getting back to the science, there is that pesky matter of diseases crossing over from one species to another. While, Harvard and eGenesis claim a victory in this area, it seems more work needs to be done.

Infections from pigs

An August 29, 2018 University of Alabama at Birmingham news release (also on EurekAlert) by Jeff Hansen, describes the latest chapter in the quest to provide more organs for transplantion,

A shortage of organs for transplantation — including kidneys and hearts — means that many patients die while still on waiting lists. So, research at the University of Alabama at Birmingham and other sites has turned to pig organs as an alternative. [emphasis mine]

Using gene-editing, researchers have modified such organs to prevent rejection, and research with primates shows the modified pig organs are well-tolerated.

An added step is needed to ensure the safety of these inter-species transplants — sensitive, quantitative assays for viruses and other infectious microorganisms in donor pigs that potentially could gain access to humans during transplantation.

The U.S. Food and Drug Administration requires such testing, prior to implantation, of tissues used for xenotransplantation from animals to humans. It is possible — though very unlikely — that an infectious agent in transplanted tissues could become an emerging infectious disease in humans.

In a paper published in Xenotransplantation, Mark Prichard, Ph.D., and colleagues at UAB have described the development and testing of 30 quantitative assays for pig infectious agents. These assays had sensitivities similar to clinical lab assays for viral loads in human patients. After validation, the UAB team also used the assays on nine sows and 22 piglets delivered from the sows through caesarian section.

“Going forward, ensuring the safety of these organs is of paramount importance,” Prichard said. “The use of highly sensitive techniques to detect potential pathogens will help to minimize adverse events in xenotransplantation.”

“The assays hold promise as part of the screening program to identify suitable donor animals, validate and release transplantable organs for research purposes, and monitor transplant recipients,” said Prichard, a professor in the UAB Department of Pediatrics and director of the Department of Pediatrics Molecular Diagnostics Laboratory.

The UAB researchers developed quantitative polymerase chain reaction, or qPCR, assays for 28 viruses sometimes found in pigs and two groups of mycoplasmas. They established reproducibility, sensitivity, specificity and lower limit of detection for each assay. All but three showed features of good quantitative assays, and the lower limit of detection values ranged between one and 16 copies of the viral or bacterial genetic material.

Also, the pig virus assays did not give false positives for some closely related human viruses.

As a start to understanding the infectious disease load in normal healthy animals and ensuring the safety of pig tissues used in xenotransplantation research, the researchers then screened blood, nasal swab and stool specimens from nine adult sows and 22 of their piglets delivered by caesarian section.

Mycoplasma species and two distinct herpesviruses were the most commonly detected microorganisms. Yet 14 piglets that were delivered from three sows infected with either or both herpesviruses were not infected with the herpesviruses, showing that transmission of these viruses from sow to the caesarian-delivery piglet was inefficient.

Prichard says the assays promise to enhance the safety of pig tissues for xenotransplantation, and they will also aid evaluation of human specimens after xenotransplantation.

The UAB researchers say they subsequently have evaluated more than 300 additional specimens, and that resulted in the detection of most of the targets. “The detection of these targets in pig specimens provides reassurance that the analytical methods are functioning as designed,” said Prichard, “and there is no a priori reason some targets might be more difficult to detect than others with the methods described here.”

As is my custom, here’s a link to and a citation for the paper,

Xenotransplantation panel for the detection of infectious agents in pigs by Caroll B. Hartline, Ra’Shun L. Conner, Scott H. James, Jennifer Potter, Edward Gray, Jose Estrada, Mathew Tector, A. Joseph Tector, Mark N. Prichard. Xenotransplantaion Volume 25, Issue 4 July/August 2018 e12427 DOI: https://doi.org/10.1111/xen.12427 First published: 18 August 2018

This paper is open access.

All this leads to questions about chimeras. If a pig is incubating organs with human cells it’s a chimera but then means the human receiving the organ becomes a chimera too. (For an example, see my Dec. 22, 2013 posting where there’s mention of a woman who received a trachea from a pig. Scroll down about 30% of the way.)

What is it to be human?

A question much beloved of philosophers and others, the question seems particularly timely with xenotransplantion and other developments such neuroprosthetics (cyborgs) and neuromorphic computing (brainlike computing).

As I’ve noted before, although not recently, popular culture offers a discourse on these issues. Take a look at the superhero movies and the way in which enhanced humans and aliens are presented. For example, X-Men comics and movies present mutants (humans with enhanced abilities) as despised and rejected. Video games (not really my thing but there is the Deus Ex series which has as its hero, a cyborg also offer insight into these issues.

Other than popular culture and in the ‘bleeding edge’ arts community, I can’t recall any public discussion on these matters arising from the extraordinary set of technologies which are being deployed or prepared for deployment in the foreseeable future.

(If you’re in Vancouver (Canada) from September 14 – December 15, 2018, you may want to check out Piccinini’s work. Also, there’s ” NCSU [North Carolina State University] Libraries, NC State’s Genetic Engineering and Society (GES) Center, and the Gregg Museum of Art & Design have issued a public call for art for the upcoming exhibition Art’s Work in the Age of Biotechnology: Shaping our Genetic Futures.” from my Sept. 6, 2018 posting. Deadline: Oct. 1, 2018.)

At a guess, there will be pushback from people who have no interest in debating what it is to be human as they already know, and will find these developments, when they learn about them, to be horrifying and unnatural.

Better technique for growing organoids taking them from the lab to the clinic

A Nov. 16, 2016 École Polytechnique Fédérale de Lausanne (EPFL) press release (also on EurekAlert) describes a new material for growing organoids,

Organoids are miniature organs that can be grown in the lab from a person’s stem cells. They can be used to model diseases, and in the future could be used to test drugs or even replace damaged tissue in patients. But currently organoids are very difficult to grow in a standardized and controlled way, which is key to designing and using them. EPFL scientists have now solved the problem by developing a patent-pending “hydrogel” that provides a fully controllable and tunable way to grow organoids. …

Organoids need a 3D scaffold

Growing organoids begins with stem cells — immature cells that can grow into any cell type of the human body and that play key roles in tissue function and regeneration. To form an organoid, the stem cells are grown inside three-dimensional gels that contain a mix of biomolecules that promote stem cell renewal and differentiation.

The role of these gels is to mimic the natural environment of the stem cells, which provides them with a protein- and sugar-rich scaffold called the “extracellular matrix”, upon which the stem cells build specific body tissues. The stem cells stick to the extracellular matrix gel, and then “self-organize” into miniature organs like retinas, kidneys, or the gut. These tiny organs retain key aspects of their real-life biology, and can be used to study diseases or test drugs before moving on to human trials.

But the current gels used for organoid growth are derived from mice, and have problems. First, it is impossible to control their makeup from batch to batch, which can cause stem cells to behave inconsistently. Second, their biochemical complexity makes them very difficult to fine-tune for studying the effect of different parameters (e.g. biological molecules, mechanical properties, etc.) on the growth of organoids. Finally, the gels can carry pathogens or immunogens, which means that they are not suitable for growing organoids to be used in the clinic.

A hydrogel solution

The lab of Matthias Lütolf at EPFL’s Institute of Bioengineering has developed a synthetic “hydrogel” that eschews the limitations of conventional, naturally derived gels. The patent-pending gel is made of water and polyethylene glycol, a substance used widely today in various forms, from skin creams and toothpastes to industrial applications and, as in this case, bioengineering.

Nikolce Gjorevski, the first author of the study, and his colleagues used the hydrogel to grow stem cells of the gut into a miniature intestine. The functional hydrogel was not only a goal in and of itself, but also a means to identify the factors that influence the stem cells’ ability to expand and form organoids. By carefully tweaking the hydrogel’s properties, they discovered that separate stages of the organoid formation process require different mechanical environments and biological components.

One such factor is a protein called fibronectin, which helps the stem cells attach to the hydrogel. Lütolf’s lab found that this attachment itself is immensely important for growing organoids, as it triggers a whole host of signals to the stem cell that tell it to grow and build an intestine-like structure. The researchers also discovered an essential role for the mechanical properties, i.e. the physical stiffness, of the gel in regulating intestinal stem cell behavior, shedding light on how cells are able to sense, process and respond to physical stimuli. This insight is particularly valuable – while the influence of biochemical signals on stem cells is well-understood, the effect of physical factors has been more mysterious.

Because the hydrogel is man-made, it is easy to control its chemical composition and key properties, and ensure consistency from batch to batch. And because it is artificial, it does not carry any risk of infection or triggering immune responses. As such, it provides a means of moving organoids from basic research to actual pharmaceutical and clinical applications in the future.

Lütolf’s lab is now researching other types of stem cells in order to extend the capacities of their hydrogel into other tissues.

Here’s a link to and a citation for the paper,

Designer matrices for intestinal stem cell and organoid culture by Nikolce Gjorevski, Norman Sachs, Andrea Manfrin, Sonja Giger, Maiia E. Bragina, Paloma Ordóñez-Morán, Hans Clevers, & Matthias P. Lutolf.  Nature (2016) doi:10.1038/nature20168 Published online 16 November 2016

This paper is behind a paywall.

North Carolina universities go beyond organ-on-a-chip

The researchers in the North Carolina universities involved in this project have high hopes according to an Oct. 9, 2015 news item on Nanowerk,

A team of researchers from the University of North Carolina at Chapel Hill and NC State University has received a $5.3 million, five-year Transformative Research (R01) Award from the National Institutes of Health (NIH) to create fully functioning versions of the human gut that fit on a chip the size of a dime.

Such “organs-on-a-chip” have become vital for biomedical research, as researchers seek alternatives to animal models for drug discovery and testing. The new grant will fund a technology that represents a major step forward for the field, overcoming limitations that have mired other efforts.

The technology will use primary cells derived directly from human biopsies, which are known to provide more relevant results than the immortalized cell lines used in current approaches. In addition, the device will sculpt these cells into the sophisticated architecture of the gut, rather than the disorganized ball of cells that are created in other miniature organ systems.

“We are building a device that goes far beyond the organ-on-a-chip,” said Nancy L. Allbritton, MD, PhD, professor and chair of the UNC-NC State joint department of biomedical engineering and one of four principle investigators on the NIH grant. “We call it a ‘simulacrum,’ [emphasis mine] a term used in science fiction to describe a duplicate. The idea is to create something that is indistinguishable from your own gut.”

I’ve come across the term ‘simulacrum’ in relation to philosophy so it’s a bit of a surprise to find it in a news release about an organ-on-a-chip where it seems to have been redefined somewhat. Here’s more from the Simulacrum entry on Wikipedia (Note: Links have been removed),

A simulacrum (plural: simulacra from Latin: simulacrum, which means “likeness, similarity”), is a representation or imitation of a person or thing.[1] The word was first recorded in the English language in the late 16th century, used to describe a representation, such as a statue or a painting, especially of a god. By the late 19th century, it had gathered a secondary association of inferiority: an image without the substance or qualities of the original.[2] Philosopher Fredric Jameson offers photorealism as an example of artistic simulacrum, where a painting is sometimes created by copying a photograph that is itself a copy of the real.[3] Other art forms that play with simulacra include trompe-l’œil,[4] pop art, Italian neorealism, and French New Wave.[3]

Philosophy

The simulacrum has long been of interest to philosophers. In his Sophist, Plato speaks of two kinds of image making. The first is a faithful reproduction, attempted to copy precisely the original. The second is intentionally distorted in order to make the copy appear correct to viewers. He gives the example of Greek statuary, which was crafted larger on the top than on the bottom so that viewers on the ground would see it correctly. If they could view it in scale, they would realize it was malformed. This example from the visual arts serves as a metaphor for the philosophical arts and the tendency of some philosophers to distort truth so that it appears accurate unless viewed from the proper angle.[5] Nietzsche addresses the concept of simulacrum (but does not use the term) in the Twilight of the Idols, suggesting that most philosophers, by ignoring the reliable input of their senses and resorting to the constructs of language and reason, arrive at a distorted copy of reality.[6]

Postmodernist French social theorist Jean Baudrillard argues that a simulacrum is not a copy of the real, but becomes truth in its own right: the hyperreal. Where Plato saw two types of representation—faithful and intentionally distorted (simulacrum)—Baudrillard sees four: (1) basic reflection of reality; (2) perversion of reality; (3) pretence of reality (where there is no model); and (4) simulacrum, which “bears no relation to any reality whatsoever”.[7] In Baudrillard’s concept, like Nietzsche’s, simulacra are perceived as negative, but another modern philosopher who addressed the topic, Gilles Deleuze, takes a different view, seeing simulacra as the avenue by which an accepted ideal or “privileged position” could be “challenged and overturned”.[8] Deleuze defines simulacra as “those systems in which different relates to different by means of difference itself. What is essential is that we find in these systems no prior identity, no internal resemblance”.[9]

Getting back to the proposed research, an Oct. (?), 2015 University of North Carolina news release, which originated the news item, describes the proposed work in more detail,

Allbritton is an expert at microfabrication and microengineering. Also on the team are intestinal stem cell expert Scott T. Magness, associate professor of medicine, biomedical engineering, and cell and molecular physiology in the UNC School of Medicine; microbiome expert Scott Bultman, associate professor of genetics in the UNC School of Medicine; and bioinformatics expert Shawn Gomez, associate professor of biomedical engineering in UNC’s College of Arts and Sciences and NC State.

The impetus for the “organ-on-chip” movement comes largely from the failings of the pharmaceutical industry. For just a single drug to go through the discovery, testing, and approval process can take as many as 15 years and as much as $5 billion dollars. Animal models are expensive to work with and often don’t respond to drugs and diseases the same way humans do. Human cells grown in flat sheets on Petri dishes are also a poor proxy. Three-dimensional “organoids” are an improvement, but these hollow balls are made of a mishmash of cells that doesn’t accurately mimic the structure and function of the real organ.

Basically, the human gut is a 30-foot long hollow tube made up of a continuous single-layer of specialized cells. Regenerative stem cells reside deep inside millions of small pits or “crypts” along the tube, and mature differentiated cells are linked to the pits and live further out toward the surface. The gut also contains trillions of microbes, which are estimated to outnumber human cells by ten to one. These diverse microbial communities – collectively known as the microbiota – process toxins and pharmaceuticals, stimulate immunity, and even release hormones to impact behavior.

To create a dime-sized version of this complex microenvironment, the UNC-NC State team borrowed fabrication technologies from the electronics and microfluidics world. The device is composed of a polymer base containing an array of imprinted or shaped “hydrogels,” a mesh of molecules that can absorb water like a sponge. These hydrogels are specifically engineered to provide the structural support and biochemical cues for growing cells from the gut. Plugged into the device will be various kinds of plumbing that bring in chemicals, fluids, and gases to provide cues that tell the cells how and where to differentiate and grow. For example, the researchers will engineer a steep oxygen gradient into the device that will enable oxygen-loving human cells and anaerobic microbes to coexist in close proximity.

“The underlying concept – to simply grow a piece of human tissue in a dish – doesn’t seem that groundbreaking,” said Magness. “We have been doing that for a long time with cancer cells, but those efforts do not replicate human physiology. Using native stem cells from the small intestine or colon, we can now develop gut tissue layers in a dish that contains stem cells and all the differentiated cells of the gut. That is the thing stem cell biologists and engineers have been shooting for, to make real tissue behave properly in a dish to create better models for drug screening and cell-based therapies. With this work, we made a big leap toward that goal.”

Right now, the team has a working prototype that can physically and chemically guide mouse intestinal stem cells into the appropriate structure and function of the gut. For several years, Magness has been isolating and banking human stem cells from samples from patients undergoing routine colonoscopies at UNC Hospitals.

As part of the grant, he will work with the rest of the team to apply these stem cells to the new device and create “simulacra” that are representative of each patient’s individual gut. The approach will enable researchers to explore in a personalized way how both the human and microbial cells of the gut behave during healthy and diseased states.

“Having a system like this will advance microbiota research tremendously,” said Bultman. “Right now microbiota studies involve taking samples, doing sequencing, and then compiling an inventory of all the microbes in the disease cases and healthy controls. These studies just draw associations, so it is difficult to glean cause and effect. This device will enable us to probe the microbiota, and gain a better understanding of whether changes in these microbial communities are the cause or the consequence of disease.”

I wish them good luck with their work and to end on another interesting note, the concept of organs-on-a-chip won a design award. From a June 22, 2015 article by Oliver Wainwright for the Guardian (Note: Links have been removed),

Meet the Lung-on-a-chip, a simulation of the biological processes inside the human lung, developed by the Wyss Institute for Biologically Inspired Engineering at Harvard University – and now crowned Design of the Year by London’s Design Museum.

Lined with living human cells, the “organs-on-chips” mimic the tissue structures and mechanical motions of human organs, promising to accelerate drug discovery, decrease development costs and potentially usher in a future of personalised medicine.

“This is the epitome of design innovation,” says Paola Antonelli, design curator at New York’s Museum of Modern Art [MOMA], who nominated the project for the award and recently acquired organs-on-chips for MoMA’s permanent collection. “Removing some of the pitfalls of human and animal testing means, theoretically, that drug trials could be conducted faster and their viable results disseminated more quickly.”

Whodathunkit? (Tor those unfamiliar with slang written in this form: Who would have thought it?)

Brushing your way to nanofibres

The scientists are using what looks like a hairbrush to create nanofibres ,

Figure 2: Brush-spinning of nanofibers. (Reprinted with permission by Wiley-VCH Verlag)) [downloaded from http://www.nanowerk.com/spotlight/spotid=41398.php]

Figure 2: Brush-spinning of nanofibers. (Reprinted with permission by Wiley-VCH Verlag)) [downloaded from http://www.nanowerk.com/spotlight/spotid=41398.php]

A Sept. 23, 2015 Nanowerk Spotlight article by Michael Berger provides an in depth look at this technique (developed by a joint research team of scientists from the University of Georgia, Princeton University, and Oxford University) which could make producing nanofibers for use in scaffolds (tissue engineering and other applications) more easily and cheaply,

Polymer nanofibers are used in a wide range of applications such as the design of new composite materials, the fabrication of nanostructured biomimetic scaffolds for artificial bones and organs, biosensors, fuel cells or water purification systems.

“The simplest method of nanofiber fabrication is direct drawing from a polymer solution using a glass micropipette,” Alexander Tokarev, Ph.D., a Research Associate in the Nanostructured Materials Laboratory at the University of Georgia, tells Nanowerk. “This method however does not scale up and thus did not find practical applications. In our new work, we introduce a scalable method of nanofiber spinning named touch-spinning.”

James Cook in a Sept. 23, 2015 article for Materials Views provides a description of the technology,

A glass rod is glued to a rotating stage, whose diameter can be chosen over a wide range of a few centimeters to more than 1 m. A polymer solution is supplied, for example, from a needle of a syringe pump that faces the glass rod. The distance between the droplet of polymer solution and the tip of the glass rod is adjusted so that the glass rod contacts the polymer droplet as it rotates.

Following the initial “touch”, the polymer droplet forms a liquid bridge. As the stage rotates the bridge stretches and fiber length increases, with the diameter decreasing due to mass conservation. It was shown that the diameter of the fiber can be precisely controlled down to 40 nm by the speed of the stage rotation.

The method can be easily scaled-up by using a round hairbrush composed of 600 filaments.

When the rotating brush touches the surface of a polymer solution, the brush filaments draw many fibers simultaneously producing hundred kilometers of fibers in minutes.

The drawn fibers are uniform since the fiber diameter depends on only two parameters: polymer concentration and speed of drawing.

Returning to Berger’s Spotlight article, there is an important benefit with this technique,

As the team points out, one important aspect of the method is the drawing of single filament fibers.

These single filament fibers can be easily wound onto spools of different shapes and dimensions so that well aligned one-directional, orthogonal or randomly oriented fiber meshes with a well-controlled average mesh size can be fabricated using this very simple method.

“Owing to simplicity of the method, our set-up could be used in any biomedical lab and facility,” notes Tokarev. “For example, a customized scaffold by size, dimensions and othermorphologic characteristics can be fabricated using donor biomaterials.”

Berger’s and Cook’s articles offer more illustrations and details.

Here’s a link to and a citation for the paper,

Touch- and Brush-Spinning of Nanofibers by Alexander Tokarev, Darya Asheghal, Ian M. Griffiths, Oleksandr Trotsenko, Alexey Gruzd, Xin Lin, Howard A. Stone, and Sergiy Minko. Advanced Materials DOI: 10.1002/adma.201502768ViewFirst published: 23 September 2015

This paper is behind a paywall.