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5 posts from April 2010

April 29, 2010

British doctors transplant trachea grown from stem cells

by Chris Kamel

In Britain, a young boy is currently recovering from a remarkable surgery to replace his windpipe. Tissue transplantation itself is hardly a routine thing, but there are a couple of things that make this case, reported in the British Medical Journal, particularly interesting.

Avoiding immune response

First, the trachea being transplanted is being grown by the boy's own cells. Stem cells, isolated from bone marrow, were used to grow a new windpipe on scaffolding from a donor trachea, stripped down to a decellularized collagen scaffold.

Traditional tissue transplant requires careful donor-recipient matching and a potential lifetime of immunosuppressant drugs to prevent immune response and tissue rejection. By regrowing a trachea using his own cells, this patient will avoid that risk.

This alone is pretty exciting, but in fact isn't the first time a trachea transplant has been done in the absence of anti-rejection drugs. In June 2008, a Columbian woman, Claudia Castillo, successfully received a transplanted trachea grown from her own stem cells, without the need for immunosuppressants. Again, a donor scaffold was produced and was then seeded with Castillo's mesenchymal stem-cell-derived chondrocytes and epithelial respiratory cells and left to grow in a special bioreactor for several days before transplant.

The body as an incubator

While Castillo's trachea was safely transplanted without drugs, it took several months to expand the stem cells before seeding the donor scaffold, and the new tissue growth required highly specialized equipment before transplant. The whole process was an expensive, multi-centre affair, and almost didn't happen due to issues transporting the stem cells from Bristol, where they were grown, to Barcelona, where the surgery took place.

In another operation, a Belgian woman, Linda De Croock, received a donor windpipe which was prepared for transplant by first implanting it in her arm. This allowed revascularization and progressive replacement of donor tissue with the patient's own. Because De Croock herself was used as the tissue incubator, it eliminated the need for special tools to incubate or grow the tissue. But again, this took several months, though the procedure allowed her to return to a normal life without the need for the usual course of drugs.

Part of what makes the British case unique is that the tissue is being grown in situ. Stem cells were isolated and ready for use within hours of extraction and surgery was performed with the new tissue being grown in the boy's body, in the correct anatomical location. This is not insignificant. It means that this or similar procedures become accessible to hospitals that may not have the facilities to grow new tissues and organs. It also reduces the wait for surgery since the tissue doesn't have to be grown beforehand. The fact that the tissue is being regrown in the body also suggests possible usefulness as a 'patch kit' for damaged tissue rather than replacing whole organs, as touched upon in a previous post.

The obvious hope is to eventually perform similar procedures with other tissues, not only reducing the risk but also donor shortages. Researchers are already working on ways to grow more complex organs. At the University of Minnesota, scientists have managed to reconstitute a partially functional rat heart using similar methods.

While growing yourself a fresh kidney for transplant is still some ways off, these are exciting steps towards rejection-free, non-donor organs thanks to stem cell-based regenerative medicine.

April 27, 2010

Neuron replacement is the future--but astrocyte replacement can be done now

Clive Svendsen

by Katie Moisse

"Neuron replacement is the future--but astrocyte replacement can be done now"

Those were the words of stem cell biologist Clive Svendsen during his plenary lecture at the American Academy of Neurology’s annual meeting in Toronto April 15. Svendsen won this year’s Sheila Essey award, which honours scientists whose research has significantly contributed to understanding, preventing and curing amyotrophic lateral sclerosis (ALS).

ALS kills motor neurons in the brain and spinal cord causing progressive paralysis and death. Efforts to stop or even slow the degeneration with drugs have had little success; so replacing the dying neurons is a plausible alternative. But the idea is fraught with challenges, such as how to deliver cells into motor areas throughout the nervous system and, once they’re in the right place, how to get their axons to connect to targets up to a metre away.

But Svendsen thinks a different cell-replacement strategy could slow ALS progression until neuron replacement is possible. In a 2007 study published in PLoS One, Svendsen and his team at the University of Wisconsin-Madison showed that neural stem cells engineered to release growth factor transplanted into the spinal cord of a rat model of ALS migrated to degenerating areas and protected motor neurons. The cells became astrocytes—a type of support cell. But the growth factor-pumping cells didn’t stave off paralysis, prompting the group to look for ways to keep the surviving motor neurons connected to their muscle targets. In a 2008 study published in Molecular Therapies, the group transplanted the same cells into rats’ spinal cords and muscles. Not only did the motor neurons survive and stay connected to the muscles longer, disease progression was delayed and survival was prolonged.

Now at Cedars-Sinai Regenerative Medicine Institute in Los Angeles, Svendsen is in the process of taking his astrocyte replacement treatment into clinical trials. But the process is tedious. He first has to amass a bank of cells that have been isolated using appropriate culture medium and programmed to pump out the growth factor by a clinical-grade lentivirus. Then he has to transplant those same cells into animal models to show they’re safe (not tumor-forming) and effective. And once the cells are just right, he has to show he can safely deliver them into human nervous tissue—a feat he plans to accomplish with a minimally invasive lumbar puncture.

The first U.S. FDA-approved trial of stem cell transplantation in ALS began in January 2010 at Emory University in Atlanta. Two patients have had multiple injections in their lumbar spinal cords, the area that controls leg movement. The phase I trial will only assess the safety of the cells and the injection, not the effects on disease progression. But patients are urged to wait for the effectiveness of stem cell treatments to be determined by properly controlled clinical trials—an April 22 episode of 60 Minutes exposed a team of medical con men in Mexico charging hopeful ALS patients $47,000 for bogus transplants. Svendsen hopes to have transplant-grade cells ready this summer.

April 26, 2010

Stem cells in the running for a Webby Award!

Webbys_m  The Canadian Stem Cell Foundation has been nominated for Best Activism Website at the 14th Annual Webby Awards, otherwise known as the "Oscars of the Internet". The Webby's recognize the world's best websites, interactive advertising, online film and video, and mobile web sites.

As a nominee, the Canadian Stem Cell Foundation is also eligible to win a Webby People's Voice Award, which is voted online by the global Web community. You can cast your vote in support of stem cells  - voting closes on April 29. The Canadian Stem Cell Foundation's website is "Renew The World", and can be found under the Website > Society > Activism category.

Winners will be announced in early May and honoured at a ceremony in New York City on June 14, where the Foundation will have an opportunity to deliver one of the Webby's famous five-word speeches. Past Webby Award winners - and their speeches - include Al Gore ("Please don't recount this vote."), Stephen Colbert ("Me. Me. Me. Me. Me."), and Michel Gondry ("Keyboards are full of germs.").

April 15, 2010

New possibilities for treatment of severe heart failure

Researchers in Montréal announced this week that they have successfully used stem cells as a key part of a treatment for a patient with heart muscle failure due to severe heart disease. The procedure involves implanting autologous stem cells into the heart muscle of a patient during a coronary bypass procedure. The stem cells stimulate greater healing and regeneration of the heart muscle tissue, which assists in the heart's ability to contract and pump more blood through the body.

The goal is to provide an alternative therapy for the treatment of severe heart failure that is less invasive and less expensive than heart replacement, currently the only treatment option for these patients. The researchers involved in the study include Nicolas Noiseux and Samer Mansour from the University of Montréal Hospital Centre and Denis-Claude Roy, Maisonneuve-Rosemont Hospital.

The study will recruit an additional 20 patients in Montréal in the first phase of the trial, with a second centre to be added in Toronto.  

Read more on the University of Montréal news page and via the Canadian Press.

See related blog posts: Overcoming barriers to successful heart transplants, Cell development to reduce the impacts of heart failure and Muscle repair enhanced by stem cells.

April 12, 2010

Stem Cell School provides new resources for educators

With new developments in stem cell biology happening all the time, high school and undergraduate biology teachers are constantly challenged with the prospect of integrating stem cells into their lesson plans. Teachers and students at last week’s StemCellTalks event in Toronto got a first look at a new media-rich resource to help educators fit stem cell science into their curricula.

StemCellSchool.org is a joint project of the Genetics Policy Institute (GPI), the Stem Cell Network, and Radiant 3-D that offers educators a single destination for the latest in stem cell science packaged in interactive animations, lesson plans, and presentation materials. The content was developed in collaboration with the National Association of Biology Teachers, and based largely around high school biology textbooks, including Biology by Neil A. Campbell and Jane B. Reece. 

The idea, according to Robert Margolin, associate director at GPI, is to offer teachers an easy way to incorporate stem cells into their lesson plans—without sacrificing the timeliness of the information.

“We tried to create a resource that provides teachers not only with information about stem cells, but information that overlaps the topics they need to teach in their classrooms,” Margolin explained. “We chose the topic of induced pluripotent stem cells as our first lesson because it talks a lot about genetics, reprogramming factors and retroviruses; there’s a whole array of biology topics that teachers need to talk about that exist within the science of cellular reprogramming.” 

Stem Cell School is not tailored to any specific curriculum, but lesson plans run across themes that biology educators present to their students.

“We compared curriculums in different states and countries in order to see what they were doing in different jurisdictions and from this, we came to the conclusion that in any biology classroom that’s teaching cellular biology and molecular biology there are certain fundamental topics that need to be taught,” Margolin said. 

Although it’s now officially launched, the Stem Cell School is far from finished. New lessons, lesson plans, presentation materials, and other information will be continually added and updated, with the first full lesson plan scheduled for release on April 15.

View the animation of cell reprogramming: