Evaluation of Hematopoietic Chimerism Following Allogeneic Peripheral Blood Stem Cell Transplantation with Amelogenin Marker

Background: Monitoring the engraftment of donor cells after allogeneic stem cell transplantation is important for the early diagnosis of graft failure or relapse of disease. The objective of the present study was to evaluate the application of the amelogenin gene for the assessment of chimerism in samples of patients who had received a sex-mismatched stem cell transplantation. Methods: A polymerase chain reaction technique was developed using a set of amelogenin gene primers alone and/or in combination with short tandem repeats primers and was preformed on blood and/or bone marrow aspiration samples of 30 recipient patients after transplantation. The technique was then set up as a routine procedure, from September 2000 through April 2006, more than 1400 samples taken from 300 stem cell transplantation patients suffering from different types of leukemia and nonmalignant hematologic disorders were evaluated for detection of chimerism after transplantation. Results: The sensitivity of the test was as low as 1 – 2%. The ratio of X/Y fragments was as the mixed chimerism. In 90% of the patients, amelogenin marker was as informative as short tandem repeats markers, as confirmed by the clinical outcome. In 5% of the patients, when there was no pre- bone marrow transplantation sample from either donor or recipient, the applicability of this assay became crucial to our treating physicians. Conclusion: The application of the amelogenin marker alone or in combination with the short tandem repeats system can be used for relative quantitative analysis of mixed chimerism and for observing kinetics of engraftment in patients who have sex-mismatched bone marrow transplantation. Amelogenin polymerase chain reaction analysis showed an excellent correlation with the short tandem repeats-polymerase chain reaction results.