الفهرس 
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Abstract
Allogeneic hematopoietic stem cell transplantation
(HSCT) has been successfully used to treat many highrisk
hematologic malignancies and marrow failure syndromes. The best results with allogeneic HSCT have been obtained in
patients receiving an allograft from a human leukocyte antigen (HLA) matched sibling. As the chance of finding an HLA
genotypically identical sibling donor is only 25%, much
attention has been focused on the use of alternative donors,
either from unrelated volunteer adult donors, umbilical cord blood (UCB), or partially matched related donors. Despite the
expansion of worldwide unrelated donor registries that have markedly improved the chances of finding a donor for many patients, the application of transplantation using unrelated adult volunteer donors remains limited by some major obstacles, including:
(1) The variable chance of finding a suitably genotypically matched unrelated donor, from 60%-70% for Caucasians to under 10% for ethnic minorities.
(2) The cumbersome process of identifying, typing, and
harvestingan unrelated donor translating to the median
time interval between initiation of a search and the
donation of marrow of about 4 months, rendering this
option less viable for patients who urgently need
transplantation. Many such patients do not maintain a
remission or survive the long waiting period until a
donation is available.
(3) Ablative allogeneic transplant using a matched unrelated donor is still associated with a high transplantrelated mortality (TRM) (30%-40%) and high long-term morbidity.
UCB donations, On the other hand, overcome some of
these limitations because of easy procurement, the absence of risk for donors, potential reduced risk of graft-versus-host Chapter Five Summary
106 disease (GVHD), and less stringent criteria for HLA matching for donor-recipient selection. However, engraftment remains a
significant concern, in part from the low number of progenitor cells contained in a single UCB unit. Delayed neutrophil recovery and TRM remain the main obstacles for successful UCB transplantation, particularly in patients receiving a
myeloablative preparative regimen.
The use of hematopoietic stem cells (HSC) from
relatives who are only partially HLA matched provides some advantages for patients lacking fully HLAmatched sibling or
unrelated donors. Virtually all patients have at least 1 HLA
partially matched parent, sibling, or child, who is immediately available to serve as a donor. Further, the immediate availability of this mismatched family member could have important treatment implications as patients will not be lost to
early relapse, and financial implications as the considerable expenditure of additional typing and procurement of unrelated
donor graft can be avoided.
Haploidentical HSCT provides an opportunity for
patients to benefit from HSCT when a 6 of 6 HLA
genotypically matched sibling is not available. It presents an
easier logistic and practical alternative to matched unrelated donor transplantation as well. This may be especially important when dealing with a patient suffering from a disease
with a rapid tempo and also for non-Caucasian patients, in
whom the chances of finding an available matched unrelated match are still low. Recent advances with effective TCD and RIC have significantly decreased the early TRM and risk of
severe GVHD, whereas enabling reliable engraftment, and hence enhancing the therapeutic benefits of haploidentical transplantation. However, posttransplant infectious
complications and relapse remain important barriers to
overcome.