Ineffective erythropoiesis and
chronic transfusion lead to iron overload. Thus, for thalassemia, a
conditioning regimen capable of eradicating an expanded bone
marrow and providing adequate immunosuppression to sustain
engraftment with acceptable toxicity on iron-damaged tissues is
required. These challenges are not present in sickle cell disease. The
approach to patients with sickle cell disease is different than in
thalassemias, due to the fact that transfusion therapy is not standard
practice for all patients, the transfusion burden is less relevant, and
the expansion of the erythroid marrow is not as massive.