All ETDs from UAB

Advisory Committee Chair

Thomas M Ryan

Advisory Committee Members

Tim Townes

Christopher Klug

Anupam Agarwal

Keith Giles

Document Type

Dissertation

Date of Award

2018

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

β-thalassemia is a group of inherited blood disorders that result in defects in β-globin chain production. Cooley’s anemia (CA), or β-thalassemia major, is the most severe form of the disease and occurs when an individual has mutations in both copies of the adult β-globin gene. Patients with CA fail to make adult hemoglobin, have ineffective erythropoiesis, suffer from severe anemia, and are transfusion dependent for life. Currently, allogeneic bone marrow transplantation (BMT) is the only cure; however, few patients have suitable donors for this procedure that carries a significant risk of morbidity and mortality. To develop new and safer alternatives to treatment of CA, a mouse model was developed to test novel therapies. As mice do not contain a fetal hemoglobin, a human γ-to-β globin switching cassette was knocked into the murine β-globin locus. When this cassette contained a hereditary persistence of fetal hemoglobin mutation in the γ-globin promoter and a non-functional human β0-globin gene, mice homozygous for the knockin were born alive, surviving solely on human fetal hemoglobin, and then demised as the γ-to-β globin switch was completed. This humanized CA mouse model yielded mice with a mean survival of two weeks. CA mice are rescued by chronic blood transfusions or cured by bone marrow transplantation. In the clinical setting, bone marrow transplantation is preceded by cytotoxic conditioning to make niche space for donor bone marrow cells to engraft. I hypothesized that by transplanting CA mice shortly after birth, cytotoxic conditioning could be avoided by exploiting the naivety of the newborn immune system. Strikingly, newborn CA mice could be rescued by BMT in the absence of cytoreductive conditioning. On the second day of life CA mice received a single antibody as conditioning and were transplanted with allogeneic cells on the following day. Transplanted mice were transfusion independent and showed physiological hematology and amelioration of disease related pathology. BMT in the absence of cytoreductive conditioning resulted in stable low-level donor hematopoietic chimerism that was capable of reconstituting the erythron. However, when donor bone marrow contained a major histocompatibility mismatch, donor cells were rejected and CA mice could not be rescued.

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