Heart may be able to repair itself

Cells located in the outermost layer of the heart can be guided to move deeper inside and help to repair a failing adult heart, new research indicates.

The cells can be guided deeper into the heart by a specific protein called thymosin beta 4, which is already known for its ability to reduce muscle cell loss after a heart attack. This protein can then instruct the heart to heal itself.

The potential repair cells are known as progenitors. These are similar to stem cells, in that they are not yet specialised into any one cell type. Instead they are blank cells that can change into different cell types depending on the signals they receive in the body.

Previously it was thought that cells within the adult heart are in a state of permanent rest and that any progenitor cells that can contribute to heart tissue repair travel into the heart from the bone marrow. However researchers at University College London have demonstrated that beneficial cells actually reside in the heart itself.

The research team studied mice which were bred to lack thymosin beta 4. They found that the hearts of these animals did not develop normally. The heart muscle showed early signs of tissue loss and blood vessel development was poor.

Closer examination revealed that without this protein, the progenitor cells failed to move deeper into the heart and change the cells needed to build healthy blood vessels and sustain muscle tissue.

"To investigate whether thymosin beta 4 could have a therapeutic effect on damaged adult hearts, my research team took cells from the outermost layer of adult mice and grew them in the lab. We found that, when treated with the protein, these adult cells have as much potential as embryonic cells to create healthy heart tissue. This suggests that the protein could have a therapeutic use", explained lead researcher, Dr Paul Riley.

Current treatments for a damaged heart are limited by the ability of the adult tissue to respond. By using this protein to guide progenitor cells from the outer layer of the heart, to form new blood vessels and nourish tissue, it could be possible to better repair damaged adult hearts.

"Our research has shown that blood vessel regeneration is still possible in the adult heart. In the future, if we can figure out how to direct the progenitor cells using thymosin beta 4, there could be potential for therapy based on the patients' own heart cells", Dr Riley explained.

He said that this process has the added benefit in that the cells are already located in the right place - within the heart itself.

"All these cells need is the appropriate instructions to guide them towards new blood vessel formation that will help in the repair of muscle damage following a heart attack", Dr Riley added.

Details of these findings are published in the journal, Nature.

[Posted: Thu 16/11/2006]

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