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Once a suitable donor has been identified, stem cells are harvested (collected) from either the bone marrow or from the bloodstream and the cells are frozen for later use. The patient (transplant recipient) then begins and completes a cycle of high-dose chemotherapy to destroy the remaining lymphoma cells. Patients are also given antirejection drugs such as tacrolimus or cyclosporine (sometimes in combination with prednisone or methotrexate) in order to reduce the likelihood that the patient will reject the donor's transplanted stem cells. The donor's frozen stem cells are then thawed and infused into the recipient via an intravenous line.

The transplantation of allogeneic hemopoietic stem cells is considered a potentially curative treatment for myelodysplastic syndromes. However, it also carries the greatest risk of death from treatment since up to 30% of patients who undergo an allogeneic transplant die within 100 days of transplantation. Recent studies suggest that it is better to wait until MDS progresses to a more advanced IPSS stage (e.g., intermediate-2 or high IPSS) before performing the transplant. Allogeneic stem cell transplantation is generally indicated for patients who are under 60 years, however, newer transplantation techniques, such as "mini-transplants", probably make allogeneic stem cell transplantation feasible for older patients.

Only about 25% of patients will have a sibling who is a suitable donor. Therefore, registries of unrelated donors who might be a match for a patient with MDS have been established. It generally takes about 3 months to identify a matched unrelated donor. Studies have demonstrated that the survival rate is higher for patients who receive transplanted cells from related donors than unrelated donors.

Autologous Stem Cell Transplantation

Autologous stem cell transplantation is a treatment option that is usually reserved for elderly patients who cannot tolerate a standard allogeneic transplant or patients for whom a suitable HLA-matched donor cannot be found. In an autologous transplant, stem cells are obtained from the marrow or peripheral blood of the patient before chemotherapy is initiated and the stem cells are then treated with special chemicals in a technique called "purging" that destroys the cancer cells but does not harm the small proportion of residual normal stem cells in the marrow or blood sample. The purged stem cell sample is then frozen and stored for later use. The stem cells are returned back into the patient's body by intravenous infusion after high-dose chemotherapy has been completed.

There are differing reports about the effectiveness of autologous stem cell transplantation in patients with myelodysplastic syndromes. Some suggest it may be beneficial when a patient is in remission. However, the ability to successfully harvest normal hematopoietic stem cells in MDS patients has been debated. It is a treatment that is being explored because it is estimated that up to 40% of patients do not have either a sibling-related or suitably matched donor. Autologous stem cell transplantation has been reported to be curative in a small number of patients. Autologous stem cell transplantation may also be initially preceded by AML-like chemotherapy and then followed with high-dose therapy.

Mini-Transplants