Autologous Stem Cells as Backup for Patients Undergoing Allogeneic Related Transplant for Thalassemia Major.

Abstract 4539

Autologous backup of harvested stem cells from patients with Beta thalassemia major, undergoing allogeneic HLA matched sibling transplantation, in order to rescue the patient in the event of graft failure, has been practiced in some transplant centers in the world. From February 2007 we instituted a program of harvesting and cryopreserving autologous bone marrow for all patients undergoing transplant for thalassemia at our center and this abstract is a report on 62 patients for whom this was done over the past 26 months till June 2009. Since most of the patients were below 10 years a bone marrow harvest was performed under general anesthesia. The harvest was depleted of red cells by gravity sedimentation using hydroxyethyl starch, plasma depleted and cryopreserved using 10% dimethyl sulfoxide and stored at -18-degC in the vapor phase of a liquid nitrogen storage system. The mean volume of the product before freezing was 180 ml. The median CD34 cell dose was 8.35 × 10⁶ cells/kg (range 0.6 to 24.6 × 10⁶ cells/kg).

During this 26 month period there was one early rejection, after initial engraftment, without autologous recovery with the patient being critically ill and febrile. Autologous stem cells were re-infused on day + 90 when the ANC was 0. However there was progressive deterioration in respiratory function and the patient died on day+92 with disseminated pulmonary aspergillosis. It is extremely difficult to decide when to re-infuse autologous stem cells in a patient who is sick post transplant and may not engraft. There was only one other rejection in this cohort of 62 patients but this patient had spontaneous recovery of autologous hematopoiesis and did not require intervention.

The total cost of harvesting autologous stem cells under anesthesia and Cryopreservation, at this center is approximately $ 1600 and this represents 10% of the total cost of an allogeneic stem cell transplant. In this cohort of 62 patients, cryopreserved stem cells were used in only one patient without preventing mortality. The increased cost, manpower and time required for this procedure needs further evaluation and also the criteria on which autologous stem cells are to be re-infused needs to be established.