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During human embryonic stem cell (ESC) hematopoietic differentiation, the description of the initial steps of lymphopoiesis remains elusive. Using a two-step culture procedure, we identified two original populations of ESC-derived hematopoietic progenitor cells (HPCs) with CD34+CD45RA+CD7− and CD34+CD45RA+CD7+ phenotypes. Bulk cultures and limiting dilution assays, culture with MS5 cells in the presence of Notch ligand Delta-like-1 (DL-1), and ex vivo colonization tests using fetal thymic organ cultures showed that although CD34+CD45RA+CD7− HPCs could generate cells of the three lymphoid lineages, their potential was skewed toward the B cell lineages. In contrast, CD34+CD45RA+CD7+ HPCs predominantly exhibited a T/natural killer (NK) cell differentiation potential. Furthermore these cells could differentiate equivalently into cells of the granulo-macrophagic lineage and dendritic cells and lacked erythroid potential. Expression profiling of 18 markers by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) revealed that CD34+CD45RA+CD7− and CD34+CD45RA+CD7 + HPCs express genes of the lymphoid specification and that CD34+CD45RA+CD7− cells express B-cell-associated genes, while CD34+CD45RA+CD7 + HPCs display a T-cell molecular profile. Altogether, these findings indicate that CD34+CD45RA+CD7− and CD34+CD45RA+CD7 + HPCs correspond to candidate multipotent early lymphoid progenitors polarized toward either the B or T/NK lineage, respectively. This work should improve our understanding of the early steps of lymphopoiesis from pluripotent stem cells and pave the way for the production of lymphocytes for cell-based immunotherapy and lymphoid development studies. [ABSTRACT FROM AUTHOR]

Rapidly progressive glomerulonephritis (RPGN) is a life-threatening clinical syndrome and a morphological manifestation of severe glomerular injury that is marked by a proliferative histological pattern ('crescents') with accumulation of T cells and macrophages and proliferation of intrinsic glomerular cells. We show de novo induction of heparin-binding epidermal growth factor-like growth factor (HB-EGF) in intrinsic glomerular epithelial cells (podocytes) from both mice and humans with RPGN. HB-EGF induction increases phosphorylation of the epidermal growth factor receptor (EGFR, also known as ErbB1) in mice with RPGN. In HB-EGF-deficient mice, EGFR activation in glomeruli is absent and the course of RPGN is improved. Autocrine HB-EGF induces a phenotypic switch in podocytes in vitro. Conditional deletion of the Egfr gene from podocytes of mice alleviates the severity of RPGN. Likewise, pharmacological blockade of EGFR also improves the course of RPGN, even when started 4 d after the induction of experimental RPGN. This suggests that targeting the HB-EGF-EGFR pathway could also be beneficial in treatment of human RPGN. [ABSTRACT FROM AUTHOR]

A correction to the article "Epidermal growth factor receptor promotes glomerular injury and renal failure in rapidly progressive crescentic glomerulonephritis," in the September 25, 2011 issue is presented.

Fanconi anemia (FA) is a rare inherited genomic instability syndrome, representing one of the best examples of hematopoietic stem cell deficiency. Although FA might be an excellent candidate forbone marrow (BM) genetic correction ex vivo, knockout animal models are not sufficient to guide preclinical steps and gene therapy attempts have proven disappointing so far. Contributing to these poor results is a characteristic and dramatic early BM cells die-off when placed in culture. We show here that human primary FA BM cell survival can be ameliorated by using specific culture conditions that limit oxidative stress. When coupled with retrovirus-mediated transfer of the main complementation group FANCA-cDNA, we could achieve long-term reconstitution of the stem cell compartment both in vitro and in vivo. Gene-corrected BM cultures grew for over 120 days and following cultured cell transplantation into NOD/ SCID mice, clonogenic human cells carrying the FANCA transgene could be detected six months after transduction. By comparison, untransduced cells died in culture by 15 days. Of necessity for ethical reasons, experiments were conducted on a very limited number of primary BM cells. Using low cytokine regimen and conditions matching regulatory requirements, a contingent of gene-corrected cells slowly emerges with an unmet potential for in vivo engraftment. Future therapeutic applications of stem cells might be expanding from these data. In addition, we provide a unique model of gene-corrected human primary cell growth which carries potential to better delineate the combined role of both DNA-damage and oxidative stress in the pathogenesis of FA.Molecular Therapy (2006) 13, S403–S403; doi: 10.1016/j.ymthe.2006.08.1148 [ABSTRACT FROM AUTHOR]