All ETDs from UAB

Advisory Committee Chair

Frederick Goldman

Advisory Committee Members

Tim Townes

Thomas Ryan

Selvarangan Ponnazhagan

Christopher Klug

Document Type

Dissertation

Date of Award

2017

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

In this dissertation, we sought to determine if a sub-myeloablative conditioning regimen followed by bone marrow transplantation/hematopoietic stem cell transplantation (HSCT) using syngeneic donor cells could facilitate donor chimerism using a clinically relevant mouse model of sickle cell disease (SCD). This pre-clinical study determined the feasibility of using sub-myeloablative conditioning in the context of autologous HSCT. The prospect of using less-intense conditioning is particularly appealing in the era of modern gene-editing technologies since its extension to use in humans will allow for HSCT to be less toxic and hence be applicable in all patients. We showed that using a sub-myeloablative dose of treosulfan (3.6 g/kg), an alkylating agent with low extramedullary toxicity profile, followed by transplantation with syngeneic bone marrow donor cells permitted long term mixed-donor chimerism and reversed the SCD phenotype in all mice. Chimeric mice showed significant improvement in hematologic parameters, normalization of urine osmolality and improvement in organ pathology. Importantly, treosulfan-treated SCD mice also had preserved fertility. We also investigated the feasibility of another sub-myeloablative conditioning regimen using the combination of treosulfan and anti-c-kit (ACK2) antibody. The maximum tolerable doses of these agents in combination was determined (treosulfan at 3 g/kg and ACK2 at 200 µg) and used to assess donor chimerism. This combinatorial regimen could not facilitate donor chimerism in SCD mice. Next, we examined if ACK2 can be used for targeted depletion of c-kit+ cells in the marrow of SCD mice. For this purpose, we first determined the ability of ACK2 in targeting c-kit+ cells in the marrow of SCD mice using PET/CT imaging and bio-distribution studies. These studies showed localization of ACK2-89Zr in the target organ, bone marrow and in lungs, liver and spleen. Localization in liver and spleen suggest that the clearance pathway was through these organs. In conclusion, this pre-clinical study points to the potential of using sub-myeloablative conditioning regimen in enabling long term erythroid chimerism in an autologous HSCT setting in SCD.

Share

COinS