Umbilical cord blood transplantation

Time-course and risk factors of hypothyroidism following allogeneic hematopoietic stem cell transplantation (HSCT) in children conditioned with fractionated total body irradiation

BACKGROUND

Hypothyroidism is a complication of hematopoietic stem cell transplantation (HSCT)1 that has been studied primarily in children after matched sibling bone marrow transplantation. Unrelated donors and umbilical cord blood (CB) are now used in transplantation, and hypothyroidism in these populations is undocumented. Children who underwent fractionated total body irradiation (fTBI) and received bone marrow or umbilical cord blood transplantation from siblings or unrelated donors were examined for hypothyroidism over time.

PROCEDURE

All children who received fTBI prior to allogeneic HSCT at The Children's Hospital (TCH), Denver between 1994 and 2002, and survived >1 year were included (N = 41 eligible; N = 33 met inclusion criteria). Probability of hypothyroidism was estimated by the Kaplan-Meier method and groups were compared using Cox's proportional hazards regression model.

RESULTS

Hypothyroidism developed in 52% of the children at a median time of 1.9 years (range 0.7-8.3 years). Primary compensated hypothyroidism was diagnosed in 94% of those affected. Children who received unrelated donor HSCT were 8.4 times more likely to develop hypothyroidism than those receiving matched sibling HSCT. Recipients of CB were 4.6 times more likely to have hypothyroidism than recipients of bone marrow.

CONCLUSIONS

There is a significant risk of developing hypothyroidism following fTBI, and allogeneic HSCT, that appears greater in recipients of unrelated donor HSCT and CB transplantation. Most of our patients who received BMT had sibling donors and the majority of CB transplants were from unrelated donors. It is difficult to determine which association is related to hypothyroidism, but the combination is significant.

Umbilical cord blood transplantation in severe T-cell immunodeficiency disorders: two-year experience

Hematopoietic stem cell transplantation is the treatment of choice for severe primary T-cell immunodeficiencies. When an HLA-identical sibling as the donor is not available, an alternative donor stem cell source is needed. In primary T-cell immunodeficiencies, T-cell-depleted HLA-haploidentical bone marrow transplantation has been particularly successful in reconstituting the immune system in many but not all of the severe T-cell immune deficiency disorders. This study reports the use of umbilical cord blood (UCB) stem cell transplantation in severe T-cell immune deficiency. Umbilical cord blood was evaluated as a stem cell source for immune reconstitution in children with severe primary T-cell immunodeficiency disorders, such as severe combined immunodeficiency syndrome (SCID), reticular dysgenesis, thymic dysplasia, combined immunodeficiency disease (CID), and Wiskott-Aldrich syndrome (WAS) when a matched sibling donor was unavailable. From 1/96 through 5/98, eight children received unrelated cord blood stem cell transplantation following a preparative regimen for the treatment of combined immunodeficiency diseases. The patients ranged in age from 2 weeks to 8 years. The cord blood units were 3/6 HLA antigen matches in two children. 4/6 in four children, and 5/6 in two child, with molecular HLA-DR mismatch in three of the children. The average time for neutrophil engraftment (absolute neutrophil count >500/mm3) was 12 days (range 10-15 days) and the average time for platelet engraftment (platelet count >20,000/mm3) was 36 days (range 24-50 days). A patient with reticular dysgenesis failed to engraft following her first transplant, but fully engrafted after a second unrelated donor cord blood transplantation. Five of six patients exhibited grade I graft-versus-host disease (GvHD). while one child had grade IV skin and gut GvHD. Immunologic reconstitution demonstrated that cord blood stem cell transplantation resulted in consistent and stable T-, B- and natural killer (NK) cell development. The kinetics of development were such that T-cell development occurred between 60 to 100 days. Initial T-cell engraftment consisted predominantly of CD45RO+, CD3+, and CD4+ T cells, and at 12 to 24 months changed to CD45RA+, CD3+, and CD4+ T cells, indicating de novo maturation of T cells. NK cell development occurred at approximately 180 days. B cells engrafted early, and study of functional B-cell antibody responses revealed that five of six patients in whom intravenous immune globulin has been discontinued have low detectable antibody responses to tetanus and diphtheria toxoid immunizations at 18 to 24 months posttransplantation. Unrelated umbilical donor cord blood is an alternative source of stem cells for transplantation in children with severe T-cell immune deficiency disorders when a suitable HLA-matched donor is not available and when a T-depleted haploidentical preparation is not beneficial. Benefits of UCB include rapid and reliable recovery of immune function, low risk of GvHD, and low viral transmission rate.