Hematopoietic Stem Cell Transplantation (HSCT) Using CD34 Selected Mismatched Related Donor and One Umbilical Cord Unit

This study is a means of providing transplantation to those patients who would be a stem cell transplant candidate who do not have an appropriate donor. The use of CD34 selected haploidentical donor with an umbilical cord unit may help provide earlier engraftment without the need for long term immunosuppression. This study tests a new method of bone marrow transplantation called combined haploidentical-cord blood transplantation. In this procedure, some of the blood forming cells (the stem cells) from a partially human leukocyte antigen (HLA) matched (haploidentical) related donor are collected from the blood, as well as cells from an umbilical cord are transplanted into the patient (the recipient) after administration of a "conditioning regimen". A conditioning regimen consists of chemotherapy and sometimes radiation to the entire body (total body irradiation, or TBI), which is meant to destroy the cancer cells and suppress the recipient's immune system to allow the transplanted cells to take (grow).