Stem cells have been used to regrow cardiac muscle in heart attack patients for the first time, researchers have reported.
A new study published this week in The Lancet has described how patients’ own cardiac stem cells have been used to stimulate the growth of healthy tissue and reduce the scarring caused by heart attacks.
“When someone has a heart attack, up to 40% of the heart dies, and dead muscle is replaced by scar, not newly-formed muscle. The scar can’t contract and it predisposes [people] to arrhythmias, heart failure and death,” said co-author Konstantinos Malliaras from the Cedar-Sinai Heart Institute in Los Angeles.
“Up until our study, the existing dogma was that the scar, once formed, is permanent; there was no way to shrink the scar tissue and regrow healthy muscle.”
Move away from bone marrow
Stem cells are a coup for this type of regenerative medicine because of their ability to produce and differentiate into different cells in the human body. When a heart attack occurs, the cardiac stem cells die and there are too few remaining stem cells to repair all the damaged tissue. Scientists thought that by infusing the heart with a large number of stem cells, this would kick-start the healing process.
Until recently, the preferred source of these stem cells was bone marrow, because of the bone marrow stem cells’ ability to produce a number of different tissues. Despite research showing that this method was safe, the effectiveness has been inconsistent across studies.
Cardiac stem cells are a more recent option and results have been positive. Malliaras and his colleagues have previously shown that cardiac stem cells are three to five times more effective than bone marrow in animals. A separate research group also used cardiac stem cells, publishing their results in the Lancet late last year. These researchers found an increased ability of the heart to pump blood and also showed reduced scar size, though they did not see new growth of healthy tissue.
Scar decreased by nearly 50%
In the current study, patients had suffered a heart attack in the four weeks prior to joining the study and were randomly split into two groups – eight patients received routine care while 17 underwent stem cell treatment. The stem cell treatment involved inserting a catheter in the neck to take a small biopsy of the heart – about the size of a course grain of sand.
“Biopsy procurement is a minimally invasive procedure that is usually performed in patients who get a heart transplant,” said Malliaras. “For the patient, biopsy procurement is entirely painless.”
Cells taken from the biopsy were harvested for 60 days on average, until a population of 25 million cells had been grown. These were then infused back into the patient’s heart. According to the researchers, MRI scans indicated remarkable results for the patients who received the stem cell treatment. “The scar was reduced by 47% and healthy cardiac tissue regrew in the place where once scar was. It is the first instance in medical history of true therapeutic regeneration in any organ,” said Malliaris.