A new research study led by University of Washington professor Michael Laflamme found that when human heart muscle cells derived from embryonic stem cells are implanted into a rat after a heart attack, they can help rebuild the animal's heart muscle and improve function of the organ.

Laflamme, an assistant professor of pathology at the UW's Center for Cardiovascular Biology in the UW Institute for Stem Cell and Regenerative Medicine, said his group began work with human embryonic stem cells shortly after President Bush's decision to allow federally funded work with those types of cells.

"[We have] had a longstanding interest in exploring cell-based therapies to enhance cardiac repair after a heart attack," he said. "We became interested in exploring human embryonic stem cells because they have an unquestioned ability to differentiate into cardiomyocytes (heart muscle cells). This is in contrast to many adult stem cell types, for which this capacity is controversial."

Laflamme and his team wondered if the cells could be put into preventative practical use.

"Our hypothesis was that we could derive a highly purified preparation of heart muscle from human embryonic stem cells [and] inject these cells into a (heart attack) model, [and then] they would rebuild the animal's heart muscle and help preserve cardiac function," he said.

Embryonic stem cells have a number of unique and attractive properties, Laflamme said.

"First, they have the potential to differentiate into any cell type in the adult organs, including heart muscle cells," he said. "Second, they can be expanded tremendously in culture. You can put a single embryonic stem cell through as many as a hundred population doublings, and it will retain the stem cell phenotype and can still be reliably differentiated into useful cell types."

In an earlier news release, Chuck Murry, corresponding author on the study and director of the Center for Cardiovascular Biology, said the problem of cell death was common in stem-cell treatments.

"When we try to regenerate with liquid tissues, like blood or bone marrow, we're pretty good at it, but we haven't been very successful with solid tissues like skeletal muscle, brain tissue, or heart muscle," Murray said. "This is one of the most successful attempts so far using cells to repair solid tissues. Every one of the treated hearts had a well-developed tissue graft."

In this study, the rats received a direct injection of the stem cell-derived cardiomyocytes or controls at a single time point, in this case four days after the experimental infarction (heart attack).

"[My lab is] pretty much focused on cardiac applications for cell therapy. There are of course other labs interested in exploring uses for stem cells in diseases involving other organs," he said.

Laflamme said his research group was successful in accomplishing their aims. In regards to the next step, he believes those cells still need to be validated for efficacy and tested for safety in a more relevant, human-like pre-clinical model.

[Reach reporter Chris Paredes at news@thedaily.washington.edu.]