Science Creates a Living Bandage for Broken Hearts

Hybrid cars are grabbing headlines, but how about "hybrid hearts"?

Merging artificially engineered products with a patient's own heart to stop or reverse cardiac damage could be the wave of the future, researchers say.

One such innovation, the "cardiac patch," is just that: A piece of living, beating cardiac tissue, grown in the lab in just a few days and applied to hearts wounded by prior heart attack or chronic disease.

"We joke that this is really 'a patch for a broken heart,'" said Gordana Vunjak-Novakovic, professor of biomedical engineering at Columbia University Medical Center in New York City, and co-director of the Tissue Engineering Resource Center at the National Institutes of Health in Bethesda, Md.

She described the new technology at a special "Hybrid Technologies" symposium held Thursday in New York City, part of the Second International Conference on Cell Therapy for Cardiovascular Diseases.

Hearts affected by heart attack or congestive heart failure develop large areas of scar tissue that is essentially non-functioning. In the most serious cases, drugs are of little help, and demand for heart transplants far outstrip the supply of donor hearts.

"So, we are trying here to make heart tissue," Vunjak-Novakovic explained. The process mimics that seen in nature, with scientists replicating the cardiac environment inside a special tissue-growing chamber called a bioreactor.

Everything has to be right: Cardiac cells must grow at a very high density but also be well-oxygenated, just as they are in the developing heart. And those cells must also be artificially electrically stimulated, since it is electric pulses that keep hearts beating.

So far, the Columbia lab has achieved real success: Vunjak-Novakovic presented video of thumbnail-sized cardiac patches rhythmically twitching just as real heart muscle does.

But the patches have not yet made their way into humans, and they may not do so for many years, Vunjak-Novakovic said.

"The real challenge is that you have to place the patch upon the heart in a way that it integrates into the heart," she said. "You don't want it to just sit there as a separate entity. It needs to connect electrically so that it syncs up with signals coming from the cells, so everything works together." Getting the patch's blood vessels to merge with those of the host heart will be another challenge, she added.

But animal trials tackling those issues are already under way, the Columbia researcher said. Someday, perhaps a decade from now, human trials might begin. And in the more distant future, the cardiac patch -- grown either from the patient or delivered "off the shelf" -- might become a routine part of cardiac care, she said.

Materials called "biopolymers" are another innovation in the cardiac-repair pipeline, according to Dr. Randall Lee, an assistant professor of medicine in the department of cardiology at the University of California, San Francisco School of Medicine.

Speaking at the meeting, he explained that these synthetic materials, with names like "alginate," "fibrin glue" and "matrigel," are injected into damaged cardiac tissue to form a kind of sticky scaffolding. In the same way that a shipwreck gives rise to a coral reef, biopolymers help gather together cells responsible for repairing and rebuilding tissue.

Biopolymers might prove especially useful for stem cell therapy, which shows great promise but has so far been disappointing when it comes to cardiovascular repair, he said.

"It may be that stem cell therapy does work -- but you're just not getting enough of the cells to stay in the area," Lee said. "You might inject 100 cells, and maybe only five stay there."

But fibrin glue, the biopolymer Lee's lab uses, comes equipped with special chemical binding sites. "These are anchors that a cell can grab on to so they stay there," he said.

In studies presented at the meeting, Lee noted that use of fibrin glue greatly increased the number of myoblasts -- progenitor heart muscle cells -- in cardiac tissue, and also boosted the formation of blood vessels. The biopolymer is gradually absorbed into tissue by about two weeks, essentially disappearing once its job is done, he said.

Lee believes second-generation biopolymers are also on the horizon, materials that will actively recruit natural, heart-healing cells and growth factors to cardiac tissue sites in need of repair.

"It's recruiting the body's own cells," he said. "That could then facilitate the whole process of regeneration."

Building Self-Esteem One Lap at a Time

January 22, 2006 08:41:11 PM PST
Hitting puberty can be like hitting a brick wall for a girl.

One day she's playing soccer and softball and hanging out with her girlfriends. The next day she can feel pressure to be pretty, thin, flirtatious and not too smart if she wants to be popular with boys.

How's a girl to navigate her way around this trap?

Molly Barker of Charlotte, N.C., thinks she's hit on a solid solution. She's the founder of Girls on the Run, an innovative program that prepares young girls for the pitfalls of puberty by combining a big dose of running with games, exercises and discussions designed to enhance a girl's self-esteem so she can enter her teens with confidence.

"I really believe that women struggle to remain true to themselves," said Barker, a former Ironman triathlete with a master's degree in social work.

When she was a teen, Barker wrestled with the pressure to fit into what she calls "the girl box," to be popular. Girls on the Run is her effort to reach young girls before they encounter such teen-years turmoil.

The effort seems to be paying off. Begun as an after-school program in 1996 with 13 third-graders from Charlotte, Girls on the Run now operates in 198 cities in the United States and Canada, and has reached approximately 40,000 eight- and nine-year-olds, Barker said. Half of the girls who participate in one 12-week, 24-lesson session sign up for more. And a new program called Girls on Track is being unveiled for older girls who are entering middle school.

"The activities make you feel really good about yourself. I've learned that you don't have to look like a supermodel to be loveable," said Madeleine Moore, a 10-year-old graduate of the Charlotte program.

"I have more confidence," agreed Tuesday Welch, an 11-year-old Charlotte graduate who has signed up for Girls on Track. "I've learned to look at myself on the inside, and not listen to what other people say about me."

A Girls on the Run program, which meets twice weekly after school, offers running at a track as the centerpiece for each session. But exercise is only part of the goal. The broader aim is to enhance the girls' social, emotional, physical and spiritual health, Barker said.

"The program is founded on three key concepts," Barker said. The first four weeks help the girls to think about themselves in an objective way -- "This is what I believe and this is what I stand for," she said.

To make it fun, Barker has created games, including one in which the names of different emotions -- anger, anxiety, joy and sadness, for example -- are written on separate index cards. The girls race each other while compiling a bingo-like collection of the cards, then talk about their own emotions and how to best manage them.

The second four weeks of the program, again including relay races and other physical activity, focuses on teamwork, dealing with conflict (such as learning how not to gossip) and building a sense of connectedness with each other.

Finally, the girls learn to understand they're part of a larger community and can use their skills and power to change the community for the better.

Nadine Koslow, professor and chief psychologist at Emory University School of Medicine, said, "This is a wonderful age to start this. The healthier foundation you have, the more you have to build on so that when things get stressful, you have the resources to cope with them."

And, she added, the non-competitive nature of the program teaches the girls teamwork and builds their self-confidence.

Melissa Welch, Tuesday's mother, is delighted with the lessons her daughter has learned from Girls on the Run, and wishes it could continue as her child gets older.

"It's going to end before she outgrows it," she said.

More information

To learn more, visit Girls on the Run.