Progress is noted in the techniques needed to build functional heart tissue:
Biomedical engineers have grown three-dimensional human heart muscle that acts just like natural tissue. This advancement could be important in treating heart attack patients or in serving as a platform for testing new heart disease medicines. The "heart patch" grown in the laboratory from human cells overcomes two major obstacles facing cell-based therapies - the patch conducts electricity at about the same speed as natural heart cells and it "squeezes" appropriately. Earlier attempts to create functional heart patches have largely been unable to overcome those obstacles. The source cells used by [the] researchers were human embryonic stem cells. These cells are pluripotent, which means that when given the right chemical and physical signals, they can be coaxed by scientists to become any kind of cell - in this case heart muscle cells, known as cardiomyocytes.
"The structural and functional properties of these 3-D tissue patches surpass all previous reports for engineered human heart muscle. This is the closest man-made approximation of native human heart tissue to date. In past studies, human stem cell-derived cardiomyocytes were not able to both rapidly conduct electrical activity and strongly contract as well as normal cardiomyocytes. Through optimization of a three-dimensional environment for cell growth, we were able to 'push' cardiomyocytes to reach unprecedented levels of electrical and mechanical maturation."
"Currently, it would take us about five to six weeks starting from pluripotent stem cells to grow a highly functional heart patch. When someone has a heart attack, a portion of the heart muscle dies. Our goal would be to implant a patch of new and functional heart tissue at the site of the injury as rapidly after heart attack as possible. Using a patient's own cells to generate pluripotent stem cells would add further advantage in that there would likely be no immune system reaction, since the cells in the patch would be recognized by the body as self."