Quantitative monitoring after double unit umbilical cord blood transplantation in an adult

Zhen LI; Hongyan ZOU; Ge SUN; Lianghong CHENG; Zhihui DENG

ABSTRACT

BACKGROUND:

Umbilical cord blood (UCB) with limited karyocytes is mainly used in child patients. Recently, physicians have tried to mix two units of cord blood in the treatment of adults with hematological system diseases.

OBJECTIVE:

To monitor quantitatively the dynamic changes and the development rules of engraftment, chimera types and relative amount after allogeneic transplantation of mixed UCB from two units in adults with leukemia.

DESIGN:

Donors and the recipient were regarded as observational subjects in umbilical cord blood transplantation (UCBT). DNA extracted from blood samples of donors and the recipient before and after transplantation was considered as detecting samples. Short tandem repeat (STR) loci were as observational measures.

SETTING:

Key Laboratory of Immunology and Genetics of Institute of Transfusion Medicine of Shenzhen Blood Center.PARTICIPANT A 43-year male patient with acute myeloid leukemia (AML), 75 kg, who was hospitalized at Shenzhen Hospital of Peking University, was enrolled in June 2005. The patient received two units of human leucocyte antigen (HLA), one locus mismatched unrelated UCBT (2.5×107 kg-1 karyocytes in UCB 1, and 1.53×107 kg-1 karyocytes in UCB 2) at month 6 after complete remission from first chemotherapy. UCB was collected from Guangzhou umbilical cord blood bank. The patient signed the informed consent.

METHODS:

The adult with AML received two units of HLA, one locus mismatched unrelated UCBT (2.5×107 kg-1 karyocytes in UCB 1, and 1.53×107 kg-1 karyocytes in UCB 2). Nine STR loci of the blood sample were determined before and after transplantation by quantitative technique of fluorescence labeling with multiplex polymerase chain reaction (MPCR), while the engraftment and chimera types were qualitatively evaluated by comparing differential loci between the recipient and the donors. The relative amount of two units of UCB was calculated in the patient after transplantation according to the differential gene peak areas of two donors with 377XL DNA sequencer after fluorescence scanning. The engraftment level and the development rules of donors' cells were analyzed quantitatively. In addition, the results were also compared with that of HLA loci distinct analysis for engraftment.MAIN OUTCOME

MEASURES:

After UCBT, transition process of nine STR loci of the recipient and two donors was observed, and engraftment was quantitatively and qualitatively described.

RESULTS:

Two units of UCB at day 15 after transplantation were engrafted simultaneously and revealed a complete chimera of the two. The relative amounts of UCB 1 and UCB 2 were 51.3% and 48.7%, respectively. Subsequently, UCB 1 went up to 70.0% and UCB 2 declined to 30.0% at day 30. However, only the genotype of UCB 1 was detected at day 52, and engraftment turned to a complete chimera of a single donor. The one with fewer karyocytes was rejected and the one with more karyocytes was engrafted for a long term.

CONCLUSION:

To detect quantitatively STR chimera with fluorescence labeling and MPCR can show precisely the engraftment level and the change of two units of UCB. It provides an accurate and reliable experimental basis for clinical UCB application and donor selection. It is proved that adult transplantation at the same time with mixed UCB from two units HLA one locus mismatched unrelated donors is feasible.