الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Allogeneic hematopoietic stem cell transplantation is a potentially curative procedure for a variety of haematological malignant and non-malignant diseases. The field has evolved substantially over the past decade, with advances in patient and donor selection, stem cell sources, supportive care and prevention of complications.
The main goal of post-transplantation is to predict negative events, such as disease relapse, graft rejection and graft-versus-host disease, in order to intervene with appropriate therapy. In this context, chimerism analysis is an important method in monitoring post hematopoietic stem cell transplantation outcome.
A variety of methods have been described to detect engraftment and the chimeric state after allogenic bone marrow transplantation. These have included sex chromosome analysis, cytogenetic analysis, RBC phenotyping, short tandem repeats (STR), and restriction fragment length polymorphism (RFLP) and variable number tandem repeats (VNTR).
VNTR loci are groups of DNA sequences that represent a source of highly polymorphic markers for individual identification. They are repetitive DNA motifs with a core repeat length ranging from 10–100 bp.
VNTR has many advantages including the use of smaller quantities of DNA, ease of preparation, faster turnaround time, and elimination of restriction enzymes and radioisotopes that are required with the other two methods. The overall cost saving is also substantial.
Chimerism can be defined on several levels. The most frequently used material for defining post-transplant chimerism is peripheral blood and bone marrow. If chimerism is analysed within certain cellular fractions, e.g. T cells, B cells, or myeloid cells, the term ‘subset chimerism’ is commonly used.
The aim of this work is to study certain number of VNTRs that were previously reported to be of value in chimerism detection, the relative distribution of their various alleles in Egyptian donor/recipient pairs, their potential value in the detection of chimerism in transplanted patients in conventional ablative transplants. Also to demonstrate the value of certain cells subset analysis in chimerism in detecting transplantation outcomes and prevention of rejection.
The current study was conducted at Alexandria University (MOASSAT Hospital) –Bone marrow transplantation unit during the period between June 2016 and February 2018. 17 patients were included (6 children and 11 adult). They were transplanted for malignant and non-malignant haematological diseases from HLA identical siblings. The median duration of follow-up was one month.
Peripheral blood samples were collected from both recipient and HLA identical sibling prior to transplantation, a second peripheral blood sample was collected from the recipient on 28th day after transplantation. The three samples were subjected to DNA extraction.
Another sample was collected from recipient on 28 th day after transplantation for its processing using T cell separation kit
VNTR analysis was performed a panel of 5 VNTR loci (D1S80,D17 S30, YNZ-22Apo B and 33.6) and 2 gene loci ( SRY and ZP3) was used.
Pre-screening the donor–recipient pair for informative variable number tandem repeats: Donor–recipient pairs were routinely done before transplantation to identify informative ones.
We found that D1S80 VNTR was the most informative allele. D17S30 VNTR and YNZ22 VNTR showed similar discriminative power which is expected as D17S30 VNTR and YNZ 22VNTR are both located on chromosome 17p13. Scientists now are considering YNZ 22 VNTR as part of D17S30 VNTR. Apo B VNTR and 33.6 VNTR was informative to some extent.
Unfortunately both gene loci (ZP3/SRY) were not informative in the present study.
Lineage-specific chimerism monitoring is progressively used to specifically detect chimerism in one or more cell subsets, which may be undetected in assessment of the whole leukocyte population. The chimerism study in different leukocyte subpopulations increases sensitivity and specificity in the monitoring after transplantation, especially the analysis of T lymphocytes.