Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A strategy to fix a broken heart

10.08.2010
These days people usually don't die from a heart attack. But the damage to heart muscle is irreversible, and most patients eventually succumb to congestive heart failure, the most common cause of death in developed countries.

Stem cells now offer hope for achieving what the body can't do: mending broken hearts. Engineers and physicians at the University of Washington have built a scaffold that supports the growth and integration of stem cell-derived cardiac muscle cells. A description of the scaffold, which supports the growth of cardiac cells in the lab and encourages blood vessel growth in living animals, is published this week in the Proceedings of the National Academy of Sciences.

"Today, if you have a heart attack there's nothing that doctors can do to repair the damage," said lead author Buddy Ratner, a UW professor of bioengineering. "You are, in essence, sentenced to a downhill slide, developing congestive heart failure that greatly shortens your lifespan."

"Your body can't make new heart cells, but what if we can deliver vital new cells in that damaged portion of the heart?"

Ratner and his colleagues built a tiny tubular porous scaffold that supports and stabilizes the fragile cardiac cells and can be injected into a damaged heart, where it will foster cell growth and eventually dissolve away. The new scaffold not only supports cardiac muscle growth, but potentially accelerates the body's ability to supply oxygen and nutrients to the transplanted tissue. Eventually, the idea is that doctors would seed the scaffold with stem cells from either the patient or a donor, then implant it when the patient is treated for a heart attack, before scar tissue has formed.

Other heart scaffolds or tissue patches currently being developed combine cardiac muscle cells and two other types of cells needed to kick-start the growth of blood vessels and connective tissue. Preparing each type of cells is an enormous amount of work, so a scaffold that requires just one type of cell, like this one, would be significantly cheaper and easier to use.

Ratner's scaffold is a flexible polymer with interconnected pores all of the same size. This one also includes channels to accommodate cardiac cells' preference for fusing together in long chains. Researchers first verified the design using chicken embryonic heart cells, and confirmed that the scaffold could support heart tissue growth at concentrations similar to those in living heart tissue.

They then seeded the scaffold with cardiac muscle cells derived from human embryonic stem cells. These cells survived and collected in the channels. Over five days, the cardiac muscle cells multiplied faster in the scaffold environment than other cell types, and could survive up to 300 micrometers (about the diameter of four human hairs) from the scaffold edge -- an important point if the scaffold is to integrate with the body.

The cells expressed two proteins associated with muscle contraction and could contract with sufficient force to deform the scaffold.

Researchers also implanted a bare scaffold into a living rat's heart to verify the scaffold's biocompatibility. Results showed that after four weeks the heart had accepted the foreign body, and new blood vessels had penetrated into the scaffold.

Why blood vessels penetrate so well is unknown. One hypothesis involves the macrophage, a cell in the immune system, and the size of the pores, which seems to be critical. The macrophages first attack the foreign body as an invader and try to digest it. They enter the pores and are themselves entrapped. At this point the macrophage seems to switch from its attack mode to its healing mode. The team is now investigating the blood vessel formation.

Heart tissues need a rich blood supply, and that's been one of the limiting factors to heart repair and vascular tissue engineering, said co-author Chuck Murry, professor of pathology and bioengineering.

"The first thing that transplanted heart cells have to do is survive. And when you transition them from a culture dish to the body, initially they don't have a blood supply. So we have to promote the host blood supply as fast as possible," Murry said.

"We're very optimistic that this scaffold will help keep the muscle cells alive after implantation and will help transition them to working heart muscles," Murry said.

The scaffold is made from a jelly-like hydrogel material developed by first author, UW bioengineering doctoral student Lauran Madden. A needle is used to implant the tiny (third of a millimeter wide by 4 millimeters long) scaffold rods into the heart muscle. But the scaffold can support growth of larger clumps of heart tissue, Madden said.

The next steps will involve adjusting the scaffold degradation time so that the scaffold degrades at the same rate that cardiac cells proliferate and that blood vessels and support fibers grow in, and then implant a cell-laden scaffold into a damaged heart.

"What we have now is a really good system going in the dish, and we're working to transition it to in the body," Madden said.

Beat BioTherapeutics, a Seattle startup co-founded by Ratner, Murry and co-author Michael Laflamme, a UW assistant professor of pathology, plans to license the technology to help bring it to patients.

Co-authors are Eric Sussman, Janet Cuy and Kip Hauch in UW bioengineering, Sarah Dupras and James Fugate in UW pathology, and Derek Mortisen, a UW chemical engineering graduate.

For more information, contact Ratner at 206-685-1005 or ratner@uweb.engr.washington.edu and Murry at 206-616-8685 or murry@uw.edu.

Talk by Charles Murry on ResearchChannel: http://www.researchchannel.org/prog/displayevent.aspx?rID=29197&fID=567

Talk by Buddy Ratner on UWTV: http://www.uwtv.org/programs/displayevent.aspx?rID=20222

The article is available at http://www.pnas.org/content/early/2010/08/02/1006442107.abstract

Hannah Hickey | EurekAlert!
Further information:
http://www.uw.edu

More articles from Life Sciences:

nachricht Brought to light – chromobodies reveal changes in endogenous protein concentration in living cells
21.09.2018 | NMI Naturwissenschaftliches und Medizinisches Institut an der Universität Tübingen

nachricht A one-way street for salt
21.09.2018 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists present new observations to understand the phase transition in quantum chromodynamics

The building blocks of matter in our universe were formed in the first 10 microseconds of its existence, according to the currently accepted scientific picture. After the Big Bang about 13.7 billion years ago, matter consisted mainly of quarks and gluons, two types of elementary particles whose interactions are governed by quantum chromodynamics (QCD), the theory of strong interaction. In the early universe, these particles moved (nearly) freely in a quark-gluon plasma.

This is a joint press release of University Muenster and Heidelberg as well as the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt.

Then, in a phase transition, they combined and formed hadrons, among them the building blocks of atomic nuclei, protons and neutrons. In the current issue of...

Im Focus: Patented nanostructure for solar cells: Rough optics, smooth surface

Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem.

"It is not enough simply to bring more light into the cell," says Christiane Becker. Such surface structures can even ultimately reduce the efficiency by...

Im Focus: New soft coral species discovered in Panama

A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.

Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the...

Im Focus: New devices based on rust could reduce excess heat in computers

Physicists explore long-distance information transmission in antiferromagnetic iron oxide

Scientists have succeeded in observing the first long-distance transfer of information in a magnetic group of materials known as antiferromagnets.

Im Focus: Finding Nemo's genes

An international team of researchers has mapped Nemo's genome

An international team of researchers has mapped Nemo's genome, providing the research community with an invaluable resource to decode the response of fish to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

"Boston calling": TU Berlin and the Weizenbaum Institute organize a conference in USA

21.09.2018 | Event News

One of the world’s most prominent strategic forums for global health held in Berlin in October 2018

03.09.2018 | Event News

4th Intelligent Materials - European Symposium on Intelligent Materials

27.08.2018 | Event News

 
Latest News

Astrophysicists measure precise rotation pattern of sun-like stars for the first time

21.09.2018 | Physics and Astronomy

Brought to light – chromobodies reveal changes in endogenous protein concentration in living cells

21.09.2018 | Life Sciences

"Boston calling": TU Berlin and the Weizenbaum Institute organize a conference in USA

21.09.2018 | Event News

VideoLinks
Science & Research
Overview of more VideoLinks >>>