In vivo modelling of normal and pathological human T-cell development

This thesis describes novel insights in human T-cell development by transplanting human HSPCs in severe immunodeficient NSG mice. First, an in vivo model was optimized to allow engraftment of hematopoietic stem cells derived from human bone marrow. This model was used to study aberrant human T-cell development in severe combined immunodeficiency (SCID) and leukemia. For SCID with known mutations as well as with atypical clinical presentation, stages of developmental arrest were determined. Using cellular barcoding, severe restriction of hematopoietic clonality during T-cell development was observed but the limited number of clones still makes up a very diverse polyclonal T-cell receptor repertoire. The restriction points coincided with arrests in development for SCID. In addition, new mechanisms whereby LMO2 causes aberrant human T-cell development, which eventually could lead to leukemia, were identified. The provided model can further aid in both fundamental studies, optimization of gene therapy approaches and stem cell expansion. Furthermore, it illustrates the need for more in depth understanding of human T-cell development, which could help improvement of T-cell reconstitution after transplantation and might aid in the diagnosis and future treatment of patients with T-ALL. Overall, the xenograft model has proven useful to advance our understanding of human T-cell development.KiKa and BD BiosciencesLUMC / Geneeskund

A unique immune signature in blood separates therapy-refractory from therapy-responsive acute graft-versus-host disease

Acute graft-versus-host disease (aGVHD) is an immune cell-driven, potentially lethal complication of allogeneic hematopoietic stem cell transplantation affecting diverse organs, including the skin, liver, and gastrointestinal (GI) tract. We applied mass cytometry (CyTOF) to dissect circulating myeloid and lymphoid cells in children with severe (grade III-IV) aGVHD treated with immune suppressive drugs alone (first-line therapy) or in combination with mesenchymal stromal cells (MSCs; second-line therapy). These results were compared with CyTOF data generated in children who underwent transplantation with no aGVHD or age-matched healthy control participants. Onset of aGVHD was associated with the appearance of CD11b(+)CD163(+) myeloid cells in the blood and accumulation in the skin and GI tract. Distinct T-cell populations, including TCR gamma delta(+) cells, expressing activation markers and chemokine receptors guiding homing to the skin and GI tract were found in the same blood samples. CXCR3(+) T cells released inflammation-promoting factors after overnight stimulation. These results indicate that lymphoid and myeloid compartments are triggered at aGVHD onset. Immunoglobulin M (IgM) presumably class switched, plasma-blasts, and 2 distinct CD11b(-) dendritic cell subsets were other prominent immune populations found early during the course of aGVHD in patients refractory to both first- and second-line (MSC-based) therapy. In these nonresponding patients, effector and regulatory T cells with skin- or gut-homing receptors also remained proportionally high over time, whereas their frequencies declined in therapy responders. Our results underscore the additive value of high-dimensional immune cell profiling for clinical response evaluation, which may assist timely decision-making in the management of severe aGVHD.Horizon 2020 (H2020)643580Immunobiology of allogeneic stem cell transplantation and immunotherapy of hematological disease

In vivo modelling of normal and pathological human T-cell development

This thesis describes novel insights in human T-cell development by transplanting human HSPCs in severe immunodeficient NSG mice. First, an in vivo model was optimized to allow engraftment of hematopoietic stem cells derived from human bone marrow. This model was used to study aberrant human T-cell development in severe combined immunodeficiency (SCID) and leukemia. For SCID with known mutations as well as with atypical clinical presentation, stages of developmental arrest were determined. Using cellular barcoding, severe restriction of hematopoietic clonality during T-cell development was observed but the limited number of clones still makes up a very diverse polyclonal T-cell receptor repertoire. The restriction points coincided with arrests in development for SCID. In addition, new mechanisms whereby LMO2 causes aberrant human T-cell development, which eventually could lead to leukemia, were identified. The provided model can further aid in both fundamental studies, optimization of gene therapy approaches and stem cell expansion. Furthermore, it illustrates the need for more in depth understanding of human T-cell development, which could help improvement of T-cell reconstitution after transplantation and might aid in the diagnosis and future treatment of patients with T-ALL. Overall, the xenograft model has proven useful to advance our understanding of human T-cell development.</p

The development of T cells from stem cells in mice and humans

Stemcel biology/Regenerative medicine (incl. bloodtransfusion

LMO2 Perturbs Human T Cell Development In Vivo by Two Different Mechanisms

Stemcel biology/Regenerative medicine (incl. bloodtransfusion

LMO2 PERTURBS HUMAN T CELL DEVELOPMENT IN VIVO BY TWO DIFFERENT MECHANISMS

Stemcel biology/Regenerative medicine (incl. bloodtransfusion

The functional relationship between hematopoietic stem cells and developing T lymphocytes

Stemcel biology/Regenerative medicine (incl. bloodtransfusion