(From EurekAlert). A Swedish study shows that adult blood stem cells used to treat heart damage do not build heart muscle cells. In general, recent work has shown that "while adult stem cells are very good at producing different types of cells in their own respective organs, they have little or no ability to form cells in other organs." Human trials have clearly demonstrated that adult stem cell therapies can repair heart damage, so scientists must now try to understand how these therapies work. Confirmation of adult stem cell limitations places greater emphasis on the need for embryonic stem cell research to further advance the capabilities of regenerative medicine.