The cells, called human bone marrow-derived multipotent stem cells (hBMSC), were implanted into animal hearts where they formed multiple cell types.
The hBMSC improved animals' heart function, said the study's lead author, Young Sup Yoon, M.D., Ph.D., assistant professor of medicine at Tufts University School of Medicine in Boston.
"This study is exciting because it is the first to show that human bone marrow includes a clonal stem cell population that can differentiate into both vessels and heart muscle. These cells can regenerate the essential tissues of the heart," Yoon said. This finding comes from animal and laboratory research. Such stem cells might be used to regenerate damaged hearts for people who have acute and chronic heart failure. They also might help people with hypertension, diabetes or other blood vessel diseases.
The researchers found that these stem cells didn't belong to any previously known bone marrow-derived stem cell population (such as hematopoietic cells, the source for all types of blood cells or mesenchymal cells that give rise to cell types like bone and cartilage).
These adult bone marrow stem cells have been shown to differentiate into all three so-called "germ layers." The three germ layers of cells in early human development are the beginnings of the body's tissues and organs. Differentiation is the term that describes the process in which stem cells change into these specialized cells.
To find out if these unique stem cells would repair heart damage, the researchers induced a heart attack in rats and introduced the hBMSC into heart tissue around the affected area. They injected unselected bone marrow cells and saline as controls.
Heart function was measured by non-invasive echocardiography and by a pressure transducer, an instrument at the tip of a tiny catheter that is threaded through an artery into the heart to measure blood pressure and heart function.
Heart function after 28 days was better in rats that received the hBMSC than in the rats that received total bone marrow cells or saline.
The transplanted hBMSC differentiated into heart muscle cells and blood vessel cells.
Important proteins that encourage blood vessel growth, called angiogenic cytokines, also increased or were newly expressed. The same thing occurred with factors important to the development of the heart in utero, called cardiac transcription factors. The number of heart and vessel cells also increased after hBMSC transplantation.
Co-authors are Andrea Wecker, M.S.; Lindsay Heyd, B.S.; Jong Seon Park, M.D., Ph.D.; Allison Hanley, B.S. and Douglas W. Losordo, M.D.
Note: Presentation time is 8:30 a.m. EST, Tuesday, Nov. 11, 2003
Note: This abstract will be featured in a news conference.