The fetal liver as an alternative stem cell source for hemolymphopoietic reconstitution

In mammalian ontogeny, the liver constitutes the primary hematopoietic organ for some time. Fetal liver cells (FLC) are rich in hematopoietic stem cells with a high proliferative potential but contain few post-thymic T cells. In animal studies, FLC restored hematopoiesis without severe graft-versus-host disease. However, genetic disparity between donor and host frequently limited durable engraftment and prevented or protracted complete immune reconstitution in most fully allogeneic recipients. Some children with severe combined immunodeficiency have been cured by FLC infusion, whereas favorable effects in aplastic anemia, acute leukemia, and inborn errors of metabolism have been limited and badly understood. Fetal liver transplantation in animals may serve as a model for the analysis and management of complications associated with the transfer of purified hematopoietic stem cell grafts and aid in the development of future therapeutic strategies requiring rapidly proliferating stem cell populations.