Figure 1.

Schematic Illustration and Theoretical Model of the Mobilization-Aided HSCT

(A) Schematic illustration. First column depicts HSCT without conditioning. Second column depicts HSCT following mobilization-based conditioning, allowing superior donor cell populations to out-compete endogenous cells. Third column depicts a theoretical HSCT procedure incorporating mobilization-based conditioning coupled with blood apheresis to remove endogenous HSCs prior to injecting donor HSCs, further enhancing donor cell competition for recently vacated niche space. Because murine models are too small to perform apheresis, this hypothetical procedure would be investigated in larger animal models. (B) Theoretical mathematical model. Assumptions are as follows: (1) the ratio of mobilized donor to recipient HSCs in circulation prior to injection of additional donor HSCs is equal to the ratio of donor to recipient HSCs in the bone marrow; (2) the total number of HSC niche spaces remains fixed; (3) each donor and recipient HSC in the blood has an equal probability of engrafting in a BM HSC niche space; and (4) remaining HSCs that are not engrafted after each cycle are cleared and are no longer present in circulation or available for engraftment during the next cycle of mobilization and transplant.