Multi-organ, multilineage engraftment by a single bone marrow-derived stem cell after transplantation in mice

Krause, D. S.; Gardner, R.; Hwang, S.; Collector, M. I.; Sharkis, S. J.; Theise, N. D.

Attention has recently been focused on the phenomenon of "transdifferentiation" in which the previous limited differentiative repertoire of stem cells derived from adult tissues has been radically challenged. Here we show that a unique bone marrow-derived stem cell population, which homes rapidly to the bone marrow (BM) after intravenous transplantation, has the capacity to differentiate, not only into mature blood cells, but also mature epithelial cells of the skin, lung, and GI tract. Female mice transplanted with PKH26 marked male-derived Fr25Lin- (selected by lineage depletion and elutriation) BM were sacrificed 2 days post-transplant and the PKH-bright cells that had homed to the BM were then transplanted as single cells into secondary female recipients. Eleven months after transplantation, the tissues of these secondary recipients were analyzed for Y-chromosome positive donor derived cells by fluorescence in situ hybridization (FISH). We solved the dilemma of identifying specific cell types while also performing FISH by submitting all specimens (3 mum sections) to a two-step analytic process. First, immunoperoxidase staining using CAM5.2, an antibody against shared epitopes of cytokeratins 8, 18, and 19, or AE1/3, specific for CK7 and 19, were used to label epithelial cells, while leaving other cell populations (e.g. stromaL, Kupffer, and hematopoietic cells) unstained. After counterstaining with hematoxylin, the sections were systematically and thoroughly color photographed at 20x magnification. For the second step of analysis, FISH for Y-chromosome was performed. As expected, Y-chromosome positive cells were found in blood cells and endothelial cells. In addition, there was clear engraftment as liver cells, hair follicle cells of the skin, pneumocytes in the lung, and GI tract lining cells. The highest engraftment (20.3 +- 4.1%) was in the alveolar lining cells of the lung, which may be due to ongoing repair of rediation induced lung injury at the time of transplantation. The % male-derived epithelial cells in bronchus, esophagus, stomach, intestine, and skin was 3.74, 1.81, 0.52, 0.87, and 3.39, respectively. A nearly embryonic level of differentiative potential of individual adult hematooietic stem cells is clearly of great scientific and clinical significance.