title: Intrathymic transplantation of bone marrow-derived progenitors provides long-term thymopoiesis.
abstract: The sustained differentiation of T cells in the thymus cannot be maintained by resident intrathymic (IT) precursors and requires that progenitors be replenished from the bone marrow (BM). In patients with severe combined immunodeficiency (SCID) treated by hematopoietic stem cell transplantation, late T-cell differentiation defects are thought to be due to an insufficient entry of donor BM progenitors into the thymus. Indeed, we find that the intravenous injection of BM progenitors into nonconditioned zeta-chain-associated protein kinase 70 (ZAP-70)-deficient mice with SCID supports short- but not long-term thymopoiesis. Remarkably, we now show that the IT administration of these progenitors produces a significant level of donor-derived thymopoiesis for more than 6 months after transplantation. In contrast to physiologic thymopoiesis, long-term donor thymopoiesis was not due to the continued recruitment of progenitors from the BM. Rather, IT transplantation resulted in the unique generation of a large population of early c-Kit(high) donor precursors within the thymus. These ZAP-70-deficient mice that received an IT transplant had a significantly increased prothymocyte niche compared with their untreated counterparts; this phenotype was associated with the generation of a medulla. Thus, IT administration of BM progenitors results in the filling of an expanded precursor niche and may represent a strategy for enhancing T-cell differentiation in patients with SCID.
authors.affiliation: Institut de Génétique Moléculaire de Montpellier, Centre National de la Recherche Scientifique (CNRS) UMR 5535/IFR 122, Montpellier, France.
authors.forename: Rita
authors.initials: R
authors.lastname: Vicente
authors.forename: Oumeya
authors.initials: O
authors.lastname: Adjali
authors.forename: Chantal
authors.initials: C
authors.lastname: Jacquet
authors.forename: Valérie S
authors.initials: VS
authors.lastname: Zimmermann
authors.forename: Naomi
authors.initials: N
authors.lastname: Taylor
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation / Q000379:methods* / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D019070:Cell Lineage / Q000235:genetics; D002478:Cells, Cultured; D007262:Infusions, Intravenous; D018655:Lymphocyte Count; D054503:Lymphoid Progenitor Cells / Q000502:physiology / Q000637:transplantation*; D038041:Lymphopoiesis / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D055153:Stem Cell Niche / Q000166:cytology; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology; D013950:Thymus Gland / Q000166:cytology* / Q000502:physiology; D013997:Time Factors; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000235:genetics
chemical_list: D051746:ZAP-70 Protein-Tyrosine Kinase