Endothelial cells but not epithelial cells or cardiomyocytes are partially replaced by donor cells after allogeneic bone marrow and stem cell transplantation

Recent studies have convincingly demonstrated that adult bone marrow contains cells capable of differentiating into a variety of cell types. To investigate whether such bone marrow-derived cells participate on self-renewal and proliferation of nonhematopoietic tissues, we studied tissue obtained by autopsy from female recipients after sex-mismatched allogeneic bone marrow and stem cell transplantation for the presence of donor-derived cells. Epithelial, endothelial, and smooth muscle cells and hematopoietic cells were characterized by double-staining immunohistochemistry with a panel of antibodies and nonisotopic in situ hybridization with a Y-chromosome-specific probe. The present study showed that the capillary endothelium was the only nonhematopoietic cell type that was replaced in a significant amount by donor cells after allogeneic stem cell and bone marrow transplantation. We could not demonstrate any participation of graft-derived cells on repopulation of cardiomyocytes or epithelial cells of the skin and gastrointestinal mucosa and of hepatocytes.