Tag Archives: Testing times: the future of animal alternatives)

University of Toronto (Canada) researchers and lab-grown heart and liver tissue (person-on-a-chip)

Usually called ‘human-on-a-chip’, a team at the University of Toronto have developed a two-organ ‘person on a chip’ according to a March 7, 2016 news item on phys.org (Note: Links have been removed),

Researchers at U of T [University of Toronto] Engineering have developed a new way of growing realistic human tissues outside the body. Their “person-on-a-chip” technology, called AngioChip, is a powerful platform for discovering and testing new drugs, and could eventually be used to repair or replace damaged organs.

Professor Milica Radisic (IBBME, ChemE), graduate student Boyang Zhang and the rest of the team are among those research groups around the world racing to find ways to grow human tissues in the lab, under conditions that mimic a real person’s body. They have developed unique methods for manufacturing small, intricate scaffolds for individual cells to grow on. These artificial environments produce cells and tissues that resemble the real thing more closely than those grown lying flat in a petri dish.

The team’s recent creations have included BiowireTM—an innovative method of growing heart cells around a silk suture—as well as a scaffold for heart cells that snaps together like sheets of Velcro. But AngioChip takes tissue engineering to a whole new level. “It’s a fully three-dimensional structure complete with internal blood vessels,” says Radisic. “It behaves just like vasculature, and around it there is a lattice for other cells to attach and grow.” …

A March 7, 2016 University of Toronto news release (also on EurekAlert), which originated the news item, provides more detail about the AngioChip,

Zhang built the scaffold out of POMaC, a polymer that is both biodegradable and biocompatible. The scaffold is built out of a series of thin layers, stamped with a pattern of channels that are each about 50 to 100 micrometres wide. The layers, which resemble the computer microchips, are then stacked into a 3D structure of synthetic blood vessels. As each layer is added, UV light is used to cross-link the polymer and bond it to the layer below.

When the structure is finished, it is bathed in a liquid containing living cells. The cells quickly attach to the inside and outside of the channels and begin growing just as they would in the human body.

“Previously, people could only do this using devices that squish the cells between sheets of silicone and glass,” says Radisic. “You needed several pumps and vacuum lines to run just one chip. Our system runs in a normal cell culture dish, and there are no pumps; we use pressure heads to perfuse media through the vasculature. The wells are open, so you can easily access the tissue.”

Using the platform, the team has built model versions of both heart and liver tissues that function like the real thing. “Our liver actually produced urea and metabolized drugs,” says Radisic. They can connect the blood vessels of the two artificial organs, thereby modelling not just the organs themselves, but the interactions between them. They’ve even injected white blood cells into the vessels and watched as they squeezed through gaps in the vessel wall to reach the tissue on the other side, just as they do in the human body.

The news release also mentions potential markets and the work that needs to be accomplished before AngioChip is available for purchase,

AngioChip has great potential in the field of pharmaceutical testing. Current drug-testing methods, such as animal testing and controlled clinical trials, are costly and fraught with ethical concerns. Testing on lab-grown human tissues would provide a realistic model at a fraction of the cost, but this area of research is still in its infancy. “In the last few years, it has become possible to order cultures of human cells for testing, but they’re grown on a plate, a two-dimensional environment,” says Radisic. “They don’t capture all the functional hallmarks of a real heart muscle, for example.”

A more realistic platform like AngioChip could enable drug companies to detect dangerous side effects and interactions between organ compartments long before their products reach the market, saving countless lives. It could also be used to understand and validate the effectiveness of current drugs and even to screen libraries of chemical compounds to discover new drugs. Through TARA Biosystems Inc., a spin-off company co-founded by Radisic, the team is already working on commercializing the technology.

In future, Radisic envisions her lab-grown tissues being implanted into the body to repair organs damaged by disease. Because the cells used to seed the platform can come from anyone, the new tissues could be genetically identical to the intended host, reducing the risk of organ rejection. Even in its current form, the team has shown that the AngioChip can be implanted into a living animal, its artificial blood vessels connected to a real circulatory system. The polymer scaffolding itself simply biodegrades after several months.

The team still has much work to do. Each AngioChip is currently made by hand; if the platform is to be used industrially, the team will need to develop high-throughput manufacturing methods to create many copies at once. Still, the potential is obvious. “It really is multifunctional, and solves many problems in the tissue engineering space,” says Radisic. “It’s truly next-generation.”

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

Biodegradable scaffold with built-in vasculature for organ-on-a-chip engineering and direct surgical anastomosis by Boyang Zhang, Miles Montgomery, M. Dean Chamberlain, Shinichiro Ogawa, Anastasia Korolj, Aric Pahnke, Laura A. Wells, Stéphane Massé, Jihye Kim, Lewis Reis, Abdul Momen, Sara S. Nunes, Aaron R. Wheeler, Kumaraswamy Nanthakumar, Gordon Keller, Michael V. Sefton, & Milica Radisic. Nature Materials (2016) doi:10.1038/nmat4570 Published online 07 March 2016

This paper is behind a paywall.

The researchers have made two images illustrating their work available. There’s this still image,

These tiny polymer scaffolds contain channels that are about 100 micrometres wide, about the same diameter as a human hair. When seeded with cells, the channels act as artificial blood vessels. By mimicking tissues in the human heart and other organs, these scaffolds provide a new way to test drugs for potentially dangerous side effects. (Image: Tyler Irving/Boyang Zhang/Kevin Soobrian)

These tiny polymer scaffolds contain channels that are about 100 micrometres wide, about the same diameter as a human hair. When seeded with cells, the channels act as artificial blood vessels. By mimicking tissues in the human heart and other organs, these scaffolds provide a new way to test drugs for potentially dangerous side effects. (Image: Tyler Irving/Boyang Zhang/Kevin Soobrian)

Perhaps more intriguing is this one,

UofT_AngioChipMoving

When seeded with heart cells, the flexible polymer scaffold contracts with a regular rhythm, just like real heart tissue. (Image: Boyang Zhang)

I have mentioned ‘human-on-a-chip’ projects many times here and as the news release writer notes, there is an international race. My July 1, 2015 posting (cross-posted from the June 30, 2015 posting [Testing times: the future of animal alternatives] on the International Innovation blog [a CORDIS-listed project dissemination partner for FP7 and H2020 projects]) notes a couple of those projects,

Organ-on-a-chip projects use stem cells to create human tissues that replicate the functions of human organs. Discussions about human-on-a-chip activities – a phrase used to describe 10 interlinked organ chips – were a highlight of the 9th World Congress on Alternatives to Animal Testing held in Prague, Czech Republic, last year. One project highlighted at the event was a joint US National Institutes of Health (NIH), US Food and Drug Administration (FDA) and US Defense Advanced Research Projects Agency (DARPA) project led by Dan Tagle that claimed it would develop functioning human-on-a-chip by 2017. However, he and his team were surprisingly close-mouthed and provided few details making it difficult to assess how close they are to achieving their goal.

By contrast, Uwe Marx – Leader of the ‘Multi-Organ-Chip’ programme in the Institute of Biotechnology at the Technical University of Berlin and Scientific Founder of TissUse, a human-on-a-chip start-up company – claims to have sold two-organ chips. He also claims to have successfully developed a four-organ chip and that he is on his way to building a human-on-a-chip. Though these chips remain to be seen, if they are, they will integrate microfluidics, cultured cells and materials patterned at the nanoscale to mimic various organs, and will allow chemical testing in an environment that somewhat mirrors a human.

As for where the University of Toronto efforts fit into the race, I don’t know for sure. It’s the first time I’ve come across a reference to liver tissue producing urea but I believe there’s at least one other team in China which has achieved a three-dimensional, more lifelike aspect for liver tissue in my Jan. 29, 2016 posting ‘Constructing a liver’.

A pragmatic approach to alternatives to animal testing

Retitled and cross-posted from the June 30, 2015 posting (Testing times: the future of animal alternatives) on the International Innovation blog (a CORDIS-listed project dissemination partner for FP7 and H2020 projects).

Maryse de la Giroday explains how emerging innovations can provide much-needed alternatives to animal testing. She also shares highlights of the 9th World Congress on Alternatives to Animal Testing.

‘Guinea pigging’ is the practice of testing drugs that have passed in vitro and in vivo tests on healthy humans in a Phase I clinical trial. In fact, healthy humans can make quite a bit of money as guinea pigs. The practice is sufficiently well-entrenched that there is a magazine, Guinea Pig Zero, devoted to professionals. While most participants anticipate some unpleasant side effects, guinea pigging can sometimes be a dangerous ‘profession’.

HARMFUL TO HEALTH

One infamous incident highlighting the dangers of guinea pigging occurred in 2006 at Northwick Park Hospital outside London. Volunteers were offered £2,000 to participate in a Phase I clinical trial to test a prospective treatment – a monoclonal antibody designed for rheumatoid arthritis and multiple sclerosis. The drug, called TGN1412, caused catastrophic systemic organ failure in participants. All six individuals receiving the drug required hospital treatment. One participant reportedly underwent amputation of fingers and toes. Another reacted with symptoms comparable to John Merrick, the Elephant Man.

The root of the disaster lay in subtle immune system differences between humans and cynomolgus monkeys – the model animal tested prior to the clinical trial. The drug was designed for the CD28 receptor on T cells. The monkeys’ receptors closely resemble those found in humans. However, unlike these monkeys, humans have other immune cells that carry CD28. The trial participants received a starting dosage that was 0.2 per cent of what the monkeys received in their final tests, but failure to take these additional receptors into account meant a dosage that was supposed to occupy 10 per cent of the available CD28 receptors instead occupied 90 per cent. After the event, a Russian inventor purchased the commercial rights to the drug and renamed it TAB08. It has been further developed by Russian company, TheraMAB, and TAB08 is reportedly in Phase II clinical trials.

HUMAN-ON-A-CHIP AND ORGANOID PROJECTS

While animal testing has been a powerful and useful tool for determining safe usage for pharmaceuticals and other types of chemicals, it is also a cruel and imperfect practice. Moreover, it typically only predicts 30-60 per cent of human responses to new drugs. Nanotechnology and other emerging innovations present possibilities for reducing, and in some cases eliminating, the use of animal models.

People for the Ethical Treatment of Animals (PETA), still better known for its publicity stunts, maintains a webpage outlining a number of alternatives including in silico testing (computer modelling), and, perhaps most interestingly, human-on-a-chip and organoid (tissue engineering) projects.

Organ-on-a-chip projects use stem cells to create human tissues that replicate the functions of human organs. Discussions about human-on-a-chip activities – a phrase used to describe 10 interlinked organ chips – were a highlight of the 9th World Congress on Alternatives to Animal Testing held in Prague, Czech Republic, last year. One project highlighted at the event was a joint US National Institutes of Health (NIH), US Food and Drug Administration (FDA) and US Defense Advanced Research Projects Agency (DARPA) project led by Dan Tagle that claimed it would develop functioning human-on-a-chip by 2017. However, he and his team were surprisingly close-mouthed and provided few details making it difficult to assess how close they are to achieving their goal.

By contrast, Uwe Marx – Leader of the ‘Multi-Organ-Chip’ programme in the Institute of Biotechnology at the Technical University of Berlin and Scientific Founder of TissUse, a human-on-a-chip start-up company – claims to have sold two-organ chips. He also claims to have successfully developed a four-organ chip and that he is on his way to building a human-on-a-chip. Though these chips remain to be seen, if they are, they will integrate microfluidics, cultured cells and materials patterned at the nanoscale to mimic various organs, and will allow chemical testing in an environment that somewhat mirrors a human.

Another interesting alternative for animal testing is organoids – a feature in regenerative medicine that can function as test sites. Engineers based at Cornell University recently published a paper on their functional, synthetic immune organ. Inspired by the lymph node, the organoid is comprised of gelatin-based biomaterials, which are reinforced with silicate nanoparticles (to keep the tissue from melting when reaching body temperature) and seeded with cells allowing it to mimic the anatomical microenvironment of a lymphatic node. It behaves like its inspiration converting B cells to germinal centres which activate, mature and mutate antibody genes when the body is under attack. The engineers claim to be able to control the immune response and to outperform 2D cultures with their 3D organoid. If the results are reproducible, the organoid could be used to develop new therapeutics.

Maryse de la Giroday is a science communications consultant and writer.

Full disclosure: Maryse de la Giroday received transportation and accommodation for the 9th World Congress on Alternatives to Animal Testing from SEURAT-1, a European Union project, making scientific inquiries to facilitate the transition to animal testing alternatives, where possible.

ETA July 1, 2015: I would like to acknowledge more sources for the information in this article,

Sources:

The guinea pigging term, the ‘professional aspect, the Northwick Park story, and the Guinea Pig Zero magazine can be found in Carl Elliot’s excellent 2006 story titled ‘Guinea-Pigging’ for New Yorker magazine.

http://www.newyorker.com/magazine/2008/01/07/guinea-pigging

Information about the drug used in the Northwick Park Hospital disaster, the sale of the rights to a Russian inventor, and the June 2015 date for the current Phase II clinical trials were found in this Wikipedia essay titled, TGN 1412.

http://en.wikipedia.org/wiki/TGN1412

Additional information about the renamed drug, TAB08 and its Phase II clinical trials was found on (a) a US government website for information on clinical trials, (b) in a Dec. 2014 (?) TheraMAB  advertisement in a Nature group magazine and a Jan. 2014 press release,

https://www.clinicaltrials.gov/ct2/show/NCT01990157?term=TAB08_RA01&rank=1

http://www.theramab.ru/TheraMAB_NAture.pdf

http://theramab.ru/en/news/phase_II

An April 2015 article (Experimental drug that injured UK volunteers resumes in human trials) by Owen Dyer for the British Medical Journal also mentioned the 2015 TheraMab Phase II clinical trials and provided information about the information about Macaque (cynomolgus) monkey tests.

http://www.bmj.com.proxy.lib.sfu.ca/content/350/bmj.h1831

BMJ 2015; 350 doi: http://dx.doi.org.proxy.lib.sfu.ca/10.1136/bmj.h1831 (Published 02 April 2015) Cite this as: BMJ 2015;350:h1831

A 2009 study by Christopher Horvath and Mark Milton somewhat contradicts the Dyer article’s contention that a species Macaque monkey was used as an animal model. (As the Dyer article is more recent and the Horvath/Milton analysis is more complex covering TGN 1412 in the context of other MAB drugs and their precursor tests along with specific TGN 1412 tests, I opted for the simple description.)

The TeGenero Incident [another name for the Northwick Park Accident] and the Duff Report Conclusions: A Series of Unfortunate Events or an Avoidable Event? by Christopher J. Horvath and Mark N. Milton. Published online before print February 24, 2009, doi: 10.1177/0192623309332986 Toxicol Pathol April 2009 vol. 37 no. 3 372-383

http://tpx.sagepub.com/content/37/3/372.full

Philippa Roxbuy’s May 24, 2013 BBC news online article provided confirmation and an additional detail or two about the Northwick Park Hospital accident. It notes that other models, in addition to animal models, are being developed.

http://www.bbc.com/news/health-22556736

Anne Ju’s excellent June 10,2015 news release about the Cornell University organoid (synthetic immune organ) project was very helpful.

http://www.news.cornell.edu/stories/2015/06/engineers-synthetic-immune-organ-produces-antibodies

There will also be a magazine article in International Innovation, which will differ somewhat from the blog posting, due to editorial style and other requirements.

ETA July 22, 2015: I now have a link to the magazine article.