Superior Long-Term Repopulating Capacity of G-CSF+Plerixafor-Mobilized Blood: Implications for Stem Cell Gene Therapy by Studies in the Hbbth-3 Mouse Model

N Psatha, E Sgouramali, A Gkountis… - Human Gene …, 2014 - liebertpub.com
N Psatha, E Sgouramali, A Gkountis, A Siametis, P Baliakas, V Constantinou, E Athanasiou…
Human Gene Therapy Methods, 2014liebertpub.com
High numbers of genetically modified hematopoietic stem cells (HSCs) equipped with
enhanced engrafting potential are required for successful stem cell gene therapy. By using
thalassemia as a model, we investigated the functional properties of hematopoietic stem and
progenitor cells (HSPCs) from Hbbth3/45.2+ mice after mobilization with G-CSF, plerixafor,
or G-CSF+ plerixafor and the engraftment kinetics of primed cells after competitive primary
and noncompetitive secondary transplantation. G-CSF+ plerixafor yielded the highest …
Abstract
High numbers of genetically modified hematopoietic stem cells (HSCs) equipped with enhanced engrafting potential are required for successful stem cell gene therapy. By using thalassemia as a model, we investigated the functional properties of hematopoietic stem and progenitor cells (HSPCs) from Hbbth3/45.2+ mice after mobilization with G-CSF, plerixafor, or G-CSF+plerixafor and the engraftment kinetics of primed cells after competitive primary and noncompetitive secondary transplantation. G-CSF+plerixafor yielded the highest numbers of HSPCs, while G-CSF+plerixafor-mobilized Hbbth3/45.2+ cells, either unmanipulated or transduced with a reporter vector, achieved faster hematologic reconstitution and higher levels of donor chimerism over all other types of mobilized cells, after competitive transplantation to B6.BoyJ/45.1+ recipients. The engraftment benefit observed in the G-CSF+plerixafor group was attributed to the more primitive stem cell phenotype of G-CSF+plerixafor-LSK cells, characterized by higher CD150+/CD48 expression. Moreover, secondary G-CSF+plerixafor recipients displayed stable or even higher chimerism levels as compared with primary engrafted mice, thus maintaining or further improving engraftment levels over G-CSF- or plerixafor-secondary recipients. Plerixafor-primed cells displayed the lowest competiveness over all other mobilized cells after primary or secondary transplantation, probably because of the higher frequency of more actively proliferating LK cells. Overall, the higher HSC yields, the faster hematological recovery, and the superiority in long-term engraftment indicate G-CSF+plerixafor-mobilized blood as an optimal graft source, not only for thalassemia gene therapy, but also for stem cell gene therapy applications in general.
Mary Ann Liebert