Doctors may one day be able to use stem cells taken from umbilical cord blood to build new heart valves for babies born with heart defects, say researchers.
'In our concept, if prenatal testing shows a heart defect, you could collect blood from the umbilical cord at birth, harvest the stem cells, and fabricate a heart valve that is ready when the baby needs it,' said Ralf Sodian, M.D., lead author of the study and a cardiac surgeon at the University Hospital of Munich.
In the study, the researchers used stem cells (CD133+ cells) derived from umbilical cord blood.
The cord blood was frozen to preserve it. After 12 weeks, the cells were seeded onto eight heart valve scaffolds constructed of a biodegradable material and then grown in a laboratory.
Afterwards, examination using electron microscopes revealed that the cells had grown into pores of the scaffolding and formed a tissue layer.
Biochemical examination indicated that the cells had not only survived and grown, but had produced important elements of the "extracellular matrix," the portion of body tissue that functions outside of cells and is essential to tissue function and structure.
Compared with human tissue from pulmonary heart valves, the tissue-engineered valves formed 77.9 percent as much collagen (the main protein in connective tissue); 85 percent as much glycosaminoglycan, a carbohydrate important in connective tissue); and 67 percent as much elastin (a protein in connective tissue).
Also, using antibodies to detect various proteins, the researchers found the valves contained desmin (a protein in muscle cells), laminin (a protein in all internal organs), alpha-actin (a protein that helps muscle cells contract) and CD31, VWF and VE-cadherin (components of blood vessel linings).
"These markers all indicate that human cardiovascular tissue was grown in the lab," Sodian said.
The study has been presented at the American Heart Association's Scientific Sessions 2008.