Stem Cells and Heart Diseases?

Published in Technology Review on March 21, 2007 By Emily Singer:-

So far, clinical studies have produced mixed results, but a new set of trials aim to sort out the best approaches to therapy.

• It's a tantalizing thought, injecting stem cells isolated from a person's own blood into an ailing heart in hopes of repairing years of accumulated decay. The trails have yielded mixed results, creating controversy over various aspects of the treatment, the type of cells that are used, the way they are delivered and when in the course of the disease they are given.
• "If it work, it could revolutionize cardiology, says Amish Raval , cardiologist at the University of Wisconsin, Madison, who is running a stem cell trial for heart failure.
• Nearly five million people in the US have heart failure caused by damage to the heart that interferes with its ability to pump blood and nearly a million people suffer heart attacks each year. Heart diseases accounts for one in every 2.8 deaths in US.
• Those people who fail on traditional medication or mechanical therapies, stem cells may have the potential to improve on that. Scientists must determine the best cells to transplant , the best way to prepare cells and when and how they should be delivered.
• The result of stem cell trials for heart disease till date were mixed, some studies found moderate improvements in a few measures of heart function, but none were able to show a clear health benefit.
• The variability comes from different methods used to purify the stem cells. As bone marrow contains two types of stem cells 1- Blood forming Stem Cells-give rise to blood cells; 2- Mesenchymal Stem Cells- give rise to muscle and bone.
• Previous trials have used a mixture of these two types of cells, some scientists think that isolating one or other cell type from mix will boost healing power to heart. "So selecting cells with therapeutic potential is a better idea, "says Raval.
• A specific type of blood forming stem cell will be injected directly into the heart muscle rather infusing the cells, that will boost growth of new blood vessels thereby increasing blood flow to the heart. "With heart failure, we think is loss of microvasculature( the smallest blood vessels), that's what we are trying to treat with the cells," says Douglas Losordo, director Cardiovascular Research Instituteat Northwestern University's Feinberg School of Medicine in Chicago.
• While all the human trials to date have used adult stem cells, scientists are not giving up on the potential of embryonic stem cells. These cells are easier to grow and manipulate. They have already been able to push embryonic stem cells to develop into clusters of heart cells that can actually beat and they are now testing different cell types for their healing power.