Stem Cell Transplantation for Hematological Malignancies

Subjects will be admitted to the bone marrow transplant unit and put in isolation to reduce
exposure to infectious agents.

Prior to transplantation, they will receive BUSULFAN via the central venous line, four times
a day for four days, CYCLOPHOSPHAMIDE via the central venous line once a day for two days,
and MELPHALAN via the central venous line for one day. Busulfan, cyclophosphamide, and
melphalan are given to destroy the subject's cancer. As well, these drugs will destroy their
immune system to help ensure the new stem cells take and grow after transplantation.

On the day of transplantation, umbilical cord blood from the donor will be transfused via
venous line. These new cells will replace the subject's bone marrow.

After transplantation, the subjects will receive Cyclosporin A and either MMF or MTX

Isolation will be continued until adequate numbers of cells are present in the blood to fight
infection. Subjects will be discharged from the hospital when medically ready. They will be
expected to return for follow-up to the blood and marrow transplant clinic at specific dates
as determined by physicians.

Inclusion Criteria:

- Patients must have a diagnosis of acute lymphocytic leukemia (ALL), acute myeloid
leukemia (AML) or myelodysplastic syndrome (MDS) and currently be in complete
remission.

- Patients must be either:

- - <18 years of age who are at least 6 months after initial hematopoietic cell
transplant (HCT),

- - 19-35 years of age and at least 18 months after initial HCT, or

- - <35 years of age and have received sufficient radiation treatment to be ineligible
for total body irradiation (TBI) containing preparative therapy

- Adequate major organ function including:

- - Cardiac: ejection fraction > or = 45%

- - Renal: creatinine clearance > or = 40 mL/min

- - Hepatic: no clinical evidence of hepatic failure (e.g. coagulopathy, ascites)

- - Karnofsky performance status > or = 70% or Lansky score > or = 50%

- Women of child bearing age must be using adequate birth control and have a negative
pregnancy test.

- Written informed consent.

Exclusion Criteria:

- Eligible for TBI containing preparative regimen.

- Active uncontrolled infection within one week of HCT.

- Pregnant or lactating females.