An estimated 20,000 of such transplants have been performed, and about half the procedures have been performed on adults.
Potential benefits for UCBT include: the high likelihood that UCB would be free of her herpesvirus contamination, banked HLA typed UBC is immediately available, UCB collections can be targeted to overcome und2242epresentation of ethnic and racial minorities.
UCB has a limited cell content, which results in delayed engraftment, and consequently effects early posttransplant survival, a problem that does not exist with bone marrow or peripheral blood hematopoietic stem cell sources.
UCB grafts have a reduced risk of severe GVHD compared to bone marrow and peripheral stem cell transplants, and therefore require less stringent HLA matching.
The vast majority of UCBTs have been mismatched in at least one HLA locus.
Currently cord blood selection is based on HLA matching at low-intermediate resolution for HLA-A and B and high resolution matching for HLA -DRB1.
Cord blood matching is referred to as 6/6, 5/6 or 4/6 relating to 0,1, or 2 mismatches with the recipient.
Optimal umbilical cord blood must consider cell dose and degree of HLA match.
The rapidity of myeloid engraftment correlates with the total nucleated cell dose of the umbilical cord blood transplant, expressed as total number of nucleated cells per kg of the patient’s weight.
Total nucleated cells is the most significant factor correlating with engraftment.
In pediatric myeloid malignancies utilizing a median infused total nucleated cell dose from 3.1-5.0 x 10 the 7th/kg and CD34+ cell dose from 1.4=2.8 x 10 to the 5th/kg.
In pediatric myeloid malignancies the incidence of grade II=IV acute GVHD ranged from 20-45% and chronic GVHD from 10-40%.
Comparing related and unrelated umbilical cord blood transplantation grafts revealed related grafts have a superior outcomes in myeloid leukemias.
Patients who receive a HLA mismatched related umbilical cord blood grafts for pediatric AML have an inferior 1 year survival of 33%, compared to recipients of HLA matched related umbilical cord blood grafts at 73%, but similar to recipients of unrelated umbilical cord blood grafts at 29%.
Center for International Blood and Marrow Transplant Research and New York Blood Center compared outcomes of cord blood transplantation and 116 bone marrow transplants with a median follow up of 45 months for the cord blood recipients and 53 months for the bone marrow recipients: all bone marrow raft were allele level matched at HLA-A, -B, -C and DRB1, while the cord blood recipients were antigen level typed at HLA-A and -B and allele level types at HLA-DRB1.
Center for International Blood and Marrow Transplant Research and New York Blood Center compared outcomes of the above study with 5-year leukemia free survival after HLA matched cord blood of 60% which was significantly higher than after transplantation with matched bone marrow at 38%.
Comparison of unrelated umbilical cord blood transplantation to unmanipulated and T cell depleted marrows in 100 children with acute myelogenous leukemia resulted in similar relapse rates of relapse, but both were lower than the T cell depleted marrow transplantation: at 2 years the umbilical transplant patients had a poorer survival than the unmanipulated marrow recipients secondary to a higher transplant related mortality of 39% vs. 19%.
Transplant related mortality similar in bone marrow recipients and in high dose matched and 1-locus mismatched cord blood recipients.
Transplant related mortality lower in allele matched bone marrow transplants recipients compared to patients transplanted with low dose 1-locus mismatched cord blood and in patients receiving 2 loci mismatched cord blood, regardless of cell dose.