The promise of a stem cell “patch” to treat cardiovascular disease may be closer to reality as scientists continue to test the device in animals, a necessary step prior to embarking on a human trial.

In theory, the heart patches, engineered tissue composed of the several different types of cells that make up heart muscle, would be implanted to replace diseased or damaged tissue and would perform all the functions of healthy, beating heart muscle, say researchers at the University of Wisconsin-Madison.

Treating diseased hearts by implanting healthy, lab-grown cells to replace damaged tissue has been an aspiration of stem cell biologists since all-purpose human stem cells were first derived and cultured there in 1998, says Timothy J. Kamp, co-director of the UW-Madison Stem Cell and Regenerative Medicine Center at the Madison, Wisc. institution.

Working with teams from the University of Alabama and Duke University in a newly funded $8.6 million consortium, Kamp and his colleagues will seek to devise and seed with the appropriate mix of cells three-dimensional patches that will be used in a pig model, a close approximation in an animal to the human heart. The seven-year study is being funded by the National Institutes of Health.

"The excitement here is we're moving closer to patient applications. We're at a stage when we need to see how these cells do in a large animal heart attack model. We'll be making patches of heart muscle that can be applied to these injured areas,” says Kamp.

Kamp's group previously has devised techniques for spinning fibroblasts in mice into progenitor master heart cells, cells capable of differentiating into all the different types of cells that make up heart muscle. Applied to human cells, the technology could provide a foundation for mass producing heart cells for clinical use in the laboratory, he notes.

Another key obstacle, Kamp notes, is making cells that, when transplanted, do not prompt an immune response by a new host. "The body's immune response is a big part of this," he says.

Finally, the researchers group must devise a heart patch in a way that it can effectively integrate into the heart of a patient. The technology is not at all like "plugging in a USB drive," says Kamp.

Building the heart patch technology and testing it in a large animal model, Kamp says, will go a long way toward harnessing the potential of stem cells to treat heart disease, which in many respects is still unproven.

"The proposed studies in animal models are essential to develop this novel therapy," Kamp says, "but the gold standard, of course, is a human patient."