PITTSBURGH, May 13 -- Bone marrow-derived cells give rise to fully functional liver cells, researchers at the University of Pittsburgh Medical Center have found through a series of transplant experiments, yielding the first report that such stem cells provide a lineage for cells making up solid organs. Study results, published in the May 14 issue of Science, suggest that bone marrow-derived cells could eventually repair or replace injured or diseased livers, reducing the need for transplantation. At a theoretical level, the findings disrupt the scientific dogma that plastic fetal cells are needed to generate the differentiated cells of adult organs.
"This is a critical paper that bridges a gap in our understanding of how the liver repairs itself under certain physiological conditions," said Bryon Petersen, Ph.D., research associate in pathology at the University of Pittsburgh's School of Medicine and lead investigator on the study.
For more than 40 years, scientists have witnessed the appearance and proliferation of a distinctive group of cells, called oval cells, under special animal experimental conditions. Normally, healthy liver cells, or hepatocytes, regenerate an injured liver. But if hepatocyte division is suppressed experimentally and the liver is subsequently injured, oval cells appear on the scene. In this setting they proliferate, then transform into several types of functional liver cells, thus helping to repair the damaged organ. The origin of oval cells has remained controversial, although they are known to carry markers also seen on bone marrow cells.
"Our animal experiments using cross-sex bone marrow transplants clearly
show that bone marrow-derived cells eventually become fully functional liver
cells, quite probably through an intermediate oval cell," said Dr. Petersen.
"The next step is finding the bone marrow stem cell giving rise to the oval cell
or discovering the signal that the liver broadcasts t
Contact: Lauren Ward
University of Pittsburgh Medical Center