February 10, 2005
Cardiac Stem Cells Found in Newborns
Discovery provides new hope for repairing damaged hearts
HealthDay News -- For the first time, researchers have found signs of stem cells in the hearts of rats, mice and humans after they were born.
The fact that the cells, which form in the right side of the heart, continue to exist after birth means they could be used to repair damage to the heart, explained Dr. Karl-Ludwig Laugwitz, co-first author of a paper appearing in the Feb. 10 issue of Nature.
Not only could the cells themselves be isolated for use, but it might also be possible to stimulate the cells in the adult heart, said Paul Sanberg, a distinguished professor of neurosurgery and director of the Center for Aging and Brain Repair at the University of South Florida in Tampa.
"It's exciting work and it has a lot of application, but it's clearly a bit away from showing that these will restore [heart] function," added Sanberg, who was not involved with the study.
Much medical hope has been pinned on stem cells, which are essentially the biological equivalent of blank slates, capable of differentiating into all types of cells needed in the body. It is hoped that one day stem cells may be able to replace or repair damaged areas of the body, including the heart.
Other research groups have reported the existence of heart stem cells, but did not provide evidence that these stem cells contributed to the development of the heart.
The current researchers first found these stem cells, called isl1+ cells, in the atrium (one of the heart's pumping chambers) of newborn mice and rats. By placing a kind of genetic 'tag' on the cells, the researchers were able to show that they went on to form beating heart muscle. According to the study authors, these stem cells evolved into fully mature and functional cells.
The cells were then found in tissue taken from five human newborns who were having surgery to correct congenital heart defects. In these types of procedures, surgeons usually throw away the region of the atrium in which these cells were found.
The cells may be involved in remodeling the heart after birth, ensuring that any defects are fixed and development is complete, the researchers speculated.
Importantly, the cells could also be cultured into millions more cells when placed on a layer of neighboring heart cells called fibroblasts. The isl1+ cells adopted the characteristics of the cells they were placed near.
The hope is that a person's own stem cells could be used to correct various medical problems. According to the researchers, these stem cells might be able to provide a cell therapy-based approach to heart disease in infants and children.
One day, Laugwitz explained, it might be possible to take a tissue specimen from a human infant undergoing surgery for a congenital heart defect, isolate the stem cells out of the tissue, amplify and differentiate them in the laboratory and return them to the infant to help grow healthy cardiac tissue.
The stem cells might also be usable for filling up holes in the heart, they said.
The next step is to try to isolate these stem cells from human beings and to transplant the isl1+ cells into living animals to observe their role in heart repair.
Visit the International Society for Stem Cell Research for more on stem cells.