Objective: In order to determine the status of engraftment following allogeneic bone marrow transplantation (allo-BMT) and predict the outcome, short tandem repeats (STR) were analysed by fluorescence labeling polymerase chain reaction (PCR).
Method: Fluorescence labeling PCR detecting STR 9 loci was established. DNA was extracted by monoclonal magnetic beads from recipients peripheral blood nucleated cells and labeled with four color fluorescences before and from 7 days to six months after allogeneic bone marrow transplantation.
Results: 1. STR and clinical feature of 12 patients after allogeneic bone marrow transplantation were analysed. In the ten patients with full donor chimeras, 8 received marrow grafts from HLA identical sibling donors, 1 from HLA identical unrelated donor and 1 from HLA haploidentical mother. All of the 10 patients had durable engraftment and survived disease-freely for 3-25 months of follow-up. 2. One patient received a HLA-AB loci mismatched graft and his STR showed mixed chimeras at day 30, and converted into full donor chimeras at day 60 after transplantation. 3. One patient received HLA haploidentical sibling donor stem cells failed to be engrafted and died 4 months later.
Conclusion: Analysis of multi-loci of STR after allo-BMT provided a real indication of engraftment. Mixed chimeras after transplantation suggested that donor lymphocytes or bone marrow cells be re-infused to enhance the conversion from mixed chimeras to full donor chimeras. For the documentation of engraftment, analysis of STR was better than any other available methods.