Bone marrow contains stem cells with the potential to differentiate into mature cells of various organs.
Scientists from the University of Texas MD Anderson Cancer Center, Houston, USA, have now examined whether circulating stem cells also have the same potential.
The research group, led by Dr Martin Körbling, gathered biopsy specimens from 12 patients who had undergone transplantation of hematopoietic stem cells from peripheral blood (11 patients) or bone marrow (1 patient).
The biopsy samples examined were taken from the liver, gastrointestinal tract, and skin of the 12 patients.
A total of 6 female patients had received transplants from a male donor, while a further 5 female subjects had received a sex-matched transplant and one an autologous transplant.
|Differentiated donor-derived cells:|
- in liver tissue after just 13 days
- in skin tissue even after 354 days
|New England Journal of Medicine|
Hematopoietic stem-cell engraftment was verified by cytogenetic analysis or restriction-fragment-length polymorphism analysis.
The biopsies were studied for the presence of donor-derived epithelial cells or hepatocytes with the use of fluorescence in situ hybridization of interphase nuclei and immunohistochemical staining for cytokeratin, CD45 (a leukocyte common antigen), and a hepatocyte-specific antigen.
All 6 recipients of sex-mismatched transplants showed evidence of complete hematopoietic donor chimerism.
XY-positive epithelial cells or hepatocytes accounted for 0 to 7% of the cells in histological sections of the biopsy specimens.
These cells were detected in liver tissue as early as Day 13 and in skin tissue as late as Day 354 after the transplantation of peripheral-blood stem cells.
The presence of donor cells in the biopsy specimens did not seem to depend on the intensity of tissue damage induced by graft-versus-venous-host disease.
Concluding on behalf of the research group, Dr Körbling said the study showed, "Circulating stem cells can differentiate into mature hepatocytes and epithelial cells of the skin and gastrointestinal tract."